Peter K Nelson, M.D.

US pipeline trial (PUFS) results
Becske T.; Shapiro M.; Nelson P.K.
2011 ;17:51-51, Interventional neuroradiology
Purpose: To evaluate safety and effectiveness of Pipeline Embolization Device for the treatment of complex intracranial aneurysms. Materials and Methods: 108 patients with large and giant, wide neck aneurysms involving the petrous, cavernous, and paraclinoid segments of the internal carotid artery were enrolled in this prospective, multicenter, single arm study. All subjects but one underwent successful treatment of the target aneurysm with Pipeline. Clinical follow-up was performed at 30 days, 180 days, and 1 year post treatment. Angiographic follow-up was obtained at 180 days (n=99) and 1 year (n=91). Completeness of aneurysm occlusion was assessed by a core laboratory. The results were compared to a predefined target aneurysm occlusion rate derived from exhaustive literature review. Safety outcomes were similarly compared to a historically defined threshold. Results: Complete aneurysm occlusion was observed in a high proportion of cases at both time points of angiographic assessments, representing a highly statistically significant result as compared to the predefined target complete occlusion rate. The safety profile of the device was acceptable, with primary safety events statistically significantly below the predefined threshold. Conclusion: Pipeline Embolization Device is effective and safe for treatment of petrous, cavernous, and paraclinoid aneurysms
— id: 146276, year: 2011, vol: 17, page: 51, stat: Journal Article,

The pipeline embolization device for the intracranial treatment of aneurysms trial
Nelson, P K; Lylyk, P; Szikora, I; Wetzel, S G; Wanke, I; Fiorella, D
2011 Jan;32(1):34-40, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Endoluminal reconstruction with flow diverting devices represents a novel constructive technique for the treatment of cerebral aneurysms. We present the results of the first prospective multicenter trial of a flow-diverting construct for the treatment of intracranial aneurysms. MATERIALS AND METHODS: Patients with unruptured aneurysms that were wide-necked (>4 mm), had unfavorable dome/neck ratios (<1.5), or had failed previous therapy were enrolled in the PITA trial between January and May 2007 at 4 (3 European and 1 South American) centers. Aneurysms were treated with the PED with or without adjunctive coil embolization. All patients underwent clinical evaluation at 30 and 180 days and conventional angiography 180 days after treatment. Angiographic results were adjudicated by an experienced neuroradiologist at a nonparticipating site. RESULTS: Thirty-one patients with 31 intracranial aneurysms (6 men; 42-76 years of age; average age, 54.6 years) were treated during the study period. Twenty-eight aneurysms arose from the ICA (5 cavernous, 15 parophthalmic, 4 superior hypophyseal, and 4 posterior communicating segments), 1 from the MCA, 1 from the vertebral artery, and 1 from the vertebrobasilar junction. Mean aneurysm size was 11.5 mm, and mean neck size was 5.8 mm. Twelve (38.7%) aneurysms had failed (or recurred after) a previous endovascular treatment. PED placement was technically successful in 30 of 31 patients (96.8%). Most aneurysms were treated with either 1 (n = 18) or 2 (n = 11) PEDs. Fifteen aneurysms (48.4%) were treated with a PED alone, while 16 were treated with both PED and embolization coils. Two patients experienced major periprocedural stroke. Follow-up angiography demonstrated complete aneurysm occlusion in 28 (93.3%) of the 30 patients who underwent angiographic follow-up. No significant in-construct stenosis (>/=50%) was identified at follow-up angiography. CONCLUSIONS: Intracranial aneurysm treatment with the PED is technically feasible and can be achieved with a safety profile analogous to that reported for stent-supported coil embolization. PED treatment elicited a very high rate (93%) of complete angiographic occlusion at 6 months in a population of the most challenging anatomic subtypes of cerebral aneurysms
— id: 120646, year: 2011, vol: 32, page: 34, stat: Journal Article,

Reconstruction of the right anterior circulation with the Pipeline embolization device to achieve treatment of a progressively symptomatic, large carotid aneurysm
Fiorella, D; Albuquerque, F; Gonzalez, F; McDougall, C G; Nelson, P K
2010 Mar 1;2(1):31-37, Journal of neurointerventional surgery
INTRODUCTION: We present the use of the Pipeline embolization device (PED) to achieve reconstruction of the right anterior circulation in a patient with a dolichoectatic internal carotid artery (ICA) and middle cerebral artery (MCA) and an associated symptomatic, large, carotid-ophthalmic segment aneurysm. CLINICAL PRESENTATION: A 36-year-old man presented with progressive right eye vision loss followed by sudden severe headache. Subsequent neuroimaging revealed a large right carotid-ophthalmic segment aneurysm and diffuse ectasia of the supraclinoid ICA and proximal MCA. A coil embolization of the aneurysm was performed without stent support. Over the next year, the patient experienced increasing headache and progressive bitemporal vision loss. Serial MRI showed progressive coil compaction and recanalization of the aneurysm. TREATMENT: The right anterior circulation was reconstructed with a total of six PEDs that extended from the distal M1 segment of the MCA proximally into the distal cavernous segment of the ICA. Follow-up angiography at 1 and 4 months demonstrated progressive complete occlusion of the aneurysm and a reorganization of blood flow to the anterior cerebral and anterior choroidal arteries. MRI and radiographic imaging provided evidence of progressive contraction of the intra-aneurysmal thrombus. The patient's headaches resolved and serial visual field examinations have demonstrated gradual improvement after treatment. CONCLUSION: Extensive cerebrovascular reconstructions that are not possible using commercially available endovascular devices can be achieved with Pipeline. The safety, efficacy and long term implications of such reconstructions are currently being defined
— id: 145782, year: 2010, vol: 2, page: 31, stat: Journal Article,

Very late thrombosis of a pipeline embolization device construct: case report
Fiorella, David; Hsu, Daniel; Woo, Henry H; Tarr, Robert W; Nelson, Peter Kim
2010 Sep;67(3 Suppl Operative):onsE313-onsE314, Neurosurgery
BACKGROUND: The Pipeline embolization device (PED) is a new endoluminal construct designed to exclude aneurysms from the parent cerebrovasculature. We report the very late (>1 year) thrombosis of a PED construct placed for the treatment of a left vertebral aneurysm. CLINICAL PRESENTATION: A patient with an occluded right vertebral artery and a large, fusiform intracranial left vertebral artery aneurysm was treated with PED and coil reconstruction. A durable, complete occlusion of the aneurysm was confirmed with control angiography at 1 year. The patient remained neurologically normal for 23 months until he experienced a transient visual disturbance followed weeks later by a minor brainstem stroke. INTERVENTION: Imaging evaluation showed thrombosis of the PED construct with complete occlusion of the left vertebral artery. After this stroke, he was initially treated with dual antiplatelet therapy and was then converted to warfarin. The patient remained neurologically stable for 5 months until he experienced progressive basilar thrombosis that ultimately resulted in a fatal stroke. CONCLUSION: The PED represents a promising new endovascular technology for the treatment of cerebral aneurysms; however, as an investigational device, long-term follow-up data are sparse at this point. The etiology of the very late thrombosis of the PED construct in this case remains unknown; however, this report underscores the need for a continued, careful systematic evaluation and close long-term follow-up of treated patients
— id: 145781, year: 2010, vol: 67, page: onsE313, stat: Journal Article,

Treatment of intracranial aneurysms by functional reconstruction of the parent artery: the Budapest experience with the pipeline embolization device
Szikora, I; Berentei, Z; Kulcsar, Z; Marosfoi, M; Vajda, Z S; Lee, W; Berez, A; Nelson, P K
2010 Jun;31(6):1139-1147, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Aneurysm treatment by intrasaccular packing has been associated with a relatively high rate of recurrence. The use of mesh tubes has recently gained traction as an alternative therapy. This article summarizes the midterm results of using an endoluminal sleeve, the PED, in the treatment of aneurysms. MATERIALS AND METHODS: A total of 19 wide-neck aneurysms were treated in 18 patients: 10 by implantation of PEDs alone and 9 by a combination of PED and coils. Angiographic and clinical results were recorded immediately and at 6 months following treatment. RESULTS: Immediate angiographic occlusion was achieved in 4 and flow reduction, in another 15 aneurysms. Angiography at 6 months demonstrated complete occlusion in 17 and partial filling in 1 of 18 patients. There was no difference between coil-packed and unpacked aneurysms. Of 28 side branches covered by > or =1 device, the ophthalmic artery was absent immediately in 1 and at 6 months in another 2 cases. One patient experienced abrupt in-stent thrombosis resulting in a transient neurologic deficit, and 1 patient died due to rupture of a coexisting aneurysm. All giant aneurysms treated with PED alone were demonstrated by follow-up cross-sectional imaging to have involuted by 6 months. CONCLUSIONS: Treatment of large, wide-neck, or otherwise untreatable aneurysms with functional reconstruction of the parent artery may be achieved with relative safety using dedicated flow-modifying devices with or without adjunctive use of intrasaccular coil packing
— id: 138164, year: 2010, vol: 31, page: 1139, stat: Journal Article,

The vascular anatomy of the vertebro-spinal axis
Becske, Tibor; Nelson, Peter Kim
2009 Jul;20(3):259-264, Neurosurgery clinics of North America
This article discusses the vascular anatomy of the vertebra-spinal axis and covers such topics as vascular supply to the spine, spinal dura, and paraspinal musculature; vascular supply to the spinal cord; and spinal veins
— id: 102936, year: 2009, vol: 20, page: 259, stat: Journal Article,

Curative cerebrovascular reconstruction with the Pipeline embolization device: the emergence of definitive endovascular therapy for intracranial aneurysms
Fiorella, D; Lylyk, P; Szikora, I; Kelly, M E; Albuquerque, F C; McDougall, C G; Nelson, P K
2009 Jul;1(1):56-65, Journal of neurointerventional surgery
Endovascular, endosaccular, coil embolization has emerged as an established therapy for both ruptured and unruptured cerebral aneurysms. However, many aneurysms are not cured using conventional endovascular techniques. Coil embolization often results in incomplete aneurysm occlusion or recanalization in the ensuing months after treatment. The Pipeline embolization device (PED; Chestnut Medical) represents a new generation endoluminal implant which is designed to treat aneurysms by reconstructing the diseased parent artery. Immediately after implantation, the PED functions to divert flow from the aneurysm, creating an environment conducive to thrombosis. With time, the PED is incorporated into the vessel wall as neointimal-endothelial overgrowth occurs along the construct. Ultimately, this process results in the durable complete exclusion of the aneurysm from the cerebrovasculature and a definitive endoluminal reconstruction of the diseased parent artery
— id: 145783, year: 2009, vol: 1, page: 56, stat: Journal Article,

Curative reconstruction of a giant midbasilar trunk aneurysm with the pipeline embolization device
Fiorella, David; Kelly, Michael E; Albuquerque, Felipe C; Nelson, Peter K
2009 Feb;64(2):212-217, Neurosurgery
OBJECTIVE: To demonstrate the curative reconstruction of a giant circumferential basilar trunk aneurysm using the Pipeline embolization device (PED) (Chestnut Medical Technologies, Inc., Menlo Park, CA) alone, without embolization coils. METHODS: A 13-year-old female patient was referred for the treatment of a 4-cm, partially thrombosed, circumferential midbasilar trunk aneurysm. Her presenting symptoms included headache, nystagmus, and left upper-extremity ataxia. Open surgical and conventional endovascular treatment options were thought to be of unacceptably high risk and unlikely to achieve a definitive treatment. The patient underwent PED treatment under a Food and Drug Administration compassionate use exemption. RESULTS: An endovascular construct was built across the affected segment of the basilar trunk with 7 serially placed, telescoping PEDs, which bridged the 29-mm aneurysm neck. Completion angiography demonstrated considerably decreased flow into the aneurysm, with stasis persisting into the venous phase of angiography. No technical complications were encountered. No new neurological symptoms were evident, and the patient's original presenting symptoms resolved completely within 24 hours after the procedure. She was discharged on postoperative Day 3. Computed tomography performed on postoperative Day 5 demonstrated no change in the size of the collective aneurysm-thrombus mass. Conventional angiography performed on postoperative Day 7 showed anatomic reconstruction of the basilar artery and complete occlusion of the circumferential aneurysm. The patient remains neurologically normal. CONCLUSION: The PED provides a safe and definitive constructive treatment option for large, giant, and fusiform/circumferential aneurysms. The PED can achieve complete aneurysm occlusion without embolization coils. When applied judiciously, the PED may be used safely in vascular segments that give rise to eloquent perforators
— id: 102610, year: 2009, vol: 64, page: 212, stat: Journal Article,

Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: the Buenos Aires experience
Lylyk, Pedro; Miranda, Carlos; Ceratto, Rosana; Ferrario, Angel; Scrivano, Esteban; Luna, Hugh Ramirez; Berez, Aaron L; Tran, Quang; Nelson, Peter K; Fiorella, David
2009 Apr;64(4):632-642, Neurosurgery
OBJECTIVES: The Pipeline embolization device (PED) (Chestnut Medical Technologies, Inc., Menlo Park, CA) is a new microcatheter-delivered endovascular construct designed to achieve the curative reconstruction of the parent arteries giving rise to wide-necked and fusiform intracranial aneurysms. We present our initial periprocedural experience with the PED and midterm follow-up results for a series of 53 patients. METHODS: Patients harboring large and giant wide-necked, nonsaccular, and recurrent intracranial aneurysms were selected for treatment. All patients were pretreated with dual antiplatelet medications for at least 72 hours before surgery and continued taking both agents for at least 6 months after treatment. A control digital subtraction angiogram was typically performed at 3, 6, and 12 months. RESULTS: Fifty-three patients (age range, 11-77 years; average age, 55.2 years; 48 female) with 63 intracranial aneurysms were treated with the PED. Small (n = 33), large (n = 22), and giant (n = 8) wide-necked aneurysms were included. A total of 72 PEDs were used. Treatment was achieved with a single PED in 44 aneurysms, with 2 overlapping PEDs in 17 aneurysms, and with 3 overlapping PEDs in 2 aneurysms. The mean time between the treatment and last follow-up digital subtraction angiogram was 5.9 months (range, 1-22 months). Complete angiographic occlusion was achieved in 56%, 93%, and 95% of aneurysms at 3 (n = 42), 6 (n = 28), and 12 (n = 18) months, respectively. The only aneurysm that remained patent at the time of the 12-month follow-up examination had been treated previously with stent-supported coiling. The presence of a preexisting endoluminal stent may have limited the efficacy of the PED reconstruction in this aneurysm. No aneurysms demonstrated a deterioration of angiographic occlusion during the follow-up period (i.e., no recanalizations). No major complications (stroke or death) were encountered during the study period. Three patients (5%), all with giant aneurysms, experienced transient exacerbations of preexisting cranial neuropathies and headache after the PED treatment. All 3 were treated with corticosteroids, and these symptoms resolved within 1 month. CONCLUSION: Endovascular reconstruction with the PED represents a safe, durable, and curative treatment of selected wide-necked, large and giant cerebral aneurysms. The rate of complete occlusion at the time of the 12-month follow-up examination approached 100% in the present study. To date, no angiographic recurrences have been observed during serial angiographic follow-up
— id: 102611, year: 2009, vol: 64, page: 632, stat: Journal Article,

Neuroendovascular management of dural arteriovenous malformations
McConnell, Kathleen A; Tjoumakaris, Stavropoula I; Allen, Jason; Shapiro, Maksim; Bescke, Tibor; Jabbour, Pascal M; Rosenwasser, Robert H; Nelson, Peter K
2009 Oct;20(4):431-439, Neurosurgery clinics of North America
Dural arteriovenous fistulas are characterized by abnormal arteriovenous shunting localized to the pachymeninges. Fistulae venous drainage is essential to their classification, symptomatology, and treatment. Endovascular therapy is rapidly progressing to an adjunct or even alternative treatment to microsurgical resection. Several techniques, such as transarterial or transvenous embolization with metallic coils, NBCA, or Onyx, have been used successfully in several studies. The long-term clinical and radiographic outcomes of endovascular therapy for the treatment of dural arteriovenous fistulas are satisfactory, and future studies are underway for the refinement of these techniques
— id: 104904, year: 2009, vol: 20, page: 431, stat: Journal Article,

Glioma vascularity correlates with reduced patient survival and increased malignancy
Russell, Stephen M; Elliott, Robert; Forshaw, David; Golfinos, John G; Nelson, Peter K; Kelly, Patrick J
2009 Sep;72(3):242-246, Surgical neurology
BACKGROUND: The objective of this study was 2-fold: (1) document the presence and degree of vascularity in gliomas of different pathologic grades and (2) determine whether the presence of abnormal vascularity, determined by catheter angiography, correlates with a shortened survival. METHODS: As part of a protocol for radiographic data acquisition that was used in a computer-assisted, stereotactic system, all patients who underwent biopsy or resection of a newly diagnosed glioma between 1994 and 2000 at our institution routinely underwent preoperative catheter angiography. The presence and degree of tumor vascularity were recorded and then correlated with survival and pathologic grade. The confounding effects of age, KPS, adjuvant treatment, and extent of resection on survival were considered. RESULTS: Two hundred thirty-one patients were included in this study. The mean follow-up of survivors was 7.8 years. Tumor vascularity correlated with a shortened survival (proportional hazards RR for survival, 0.69; 95% CI, 0.58-0.82). This correlation persisted after correction for age, KPS score, adjuvant therapy, and extent of resection (RR, 0.81; 95% CI, 0.68-0.97). Abnormal vascularity was present in 25 (30%) of 82 low-grade (WHO grade 2) gliomas. Overall, the extent of vascularity (none [120 patients, 52%], blush [63 patients, 27%], neovessels [25 patients, 11%], and arteriovenous shunting [23 patients, 10%]) correlated with worse WHO tumor grade (P < .0001). CONCLUSIONS: The presence of abnormal vascularity correlates with both a shortened survival and higher grade of malignancy. These findings underscore the importance of antiangiogenesis factor investigation and drug development for the treatment of gliomas, regardless of their pathologic grade
— id: 101316, year: 2009, vol: 72, page: 242, stat: Journal Article,

Definitive reconstruction of circumferential, fusiform intracranial aneurysms with the pipeline embolization device
Fiorella, David; Woo, Henry H; Albuquerque, Felipe C; Nelson, Peter K
2008 May;62(5):1115-1120, Neurosurgery
OBJECTIVE: The Pipeline embolization device (PED; Chestnut Medical, Menlo Park, CA) is a new endovascular construct designed to exclude aneurysms from the parent cerebrovasculature. We report the results of the first two human implantations of this device in North America. CLINICAL PRESENTATION: Two patients presenting with large, symptomatic, circumferential, fusiform intracranial vertebral artery aneurysms were treated with the PED. In both cases, more traditional open microneurosurgical and neuroendovascular treatment strategies had either failed or were associated with unacceptably high risk. INTERVENTION: Three PEDs were placed across the aneurysms in each of the patients to achieve reconstruction of a new parent vessel through the center of a circumferential aneurysm. In the first patient, who had previously been treated with stent-supported coil embolization, the PED construct alone was sufficient to achieve parent vessel reconstruction and exclusion of the recurrent aneurysm. In the second patient, a microcatheter was jailed within the saccular portion of the aneurysm and the parent vessel was reconstructed with three telescoped PEDs. Although the PED construct dramatically reduced flow into the aneurysm, the lesion remained patent. Coiling of the saccular portion of the aneurysm was subsequently performed via the jailed microcatheter. Follow-up angiography performed 72 hours after the procedure demonstrated occlusion of the aneurysm with cylindrical reconstruction of the affected vascular segment. Neither patient has experienced any complication in the periprocedural period (30 d) or during subsequent long-term (>1 year) follow-up. CONCLUSION: The PED represents an important advance in the endovascular therapy of cerebral aneurysms, targeting primary parent vessel reconstruction rather than endosaccular occlusion as a means by which to achieve exclusion of the aneurysm and definitive anatomic reconstruction of the parent artery
— id: 91713, year: 2008, vol: 62, page: 1115, stat: Journal Article,

Safety and efficacy of adjunctive balloon remodeling during endovascular treatment of intracranial aneurysms: a literature review
Shapiro, M; Babb, J; Becske, T; Nelson, P K
2008 Oct;29(9):1777-1781, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Concurrent temporary inflation of a nondetachable balloon in the parent artery has been reported to be useful during endovascular coiling of complex, wide-neck aneurysms, facilitating truer coil reconstruction of the native vessel. Nevertheless, there exists concern that adjunctive use of balloon assistance may lead to increased adverse events during aneurysm coiling. MATERIALS AND METHODS: A literature search of all of the unassisted and balloon-remodeling studies published between 1997 and 2006 was conducted with application of strict selection criteria based on the reporting of complication incidence and outcome. The final cohort was analyzed to determine rates and clinical outcomes of iatrogenic aneurysm rupture and thromboembolism. Additional data were collected on the degree of initial and follow-up aneurysm occlusion rates. RESULTS: A total of 83 potential studies (4973 patients) were identified, from which 23 articles reporting results for 867 traditional-unassisted and 273 balloon-assisted coiled aneurysms met inclusion criteria for the analysis of thromboembolic complications, and 21 articles with 993 routinely coiled and 170 balloon-remodeled aneurysms were eligible for iatrogenic perforation analysis. No statistically significant difference was found in the rates of thromboembolism. Iatrogenic perforation rates were also comparable, though the overall numbers were too few for meaningful statistical analysis. Both initial and follow-up aneurysm occlusion rates were higher in balloon-assisted cases. CONCLUSION: This largest-to-date literature review and meta-analysis did not demonstrate a higher incidence of thromboembolic events or iatrogenic rupture with the use of adjunctive balloon remodeling compared with unassisted coiling. Balloon remodeling appears to result in higher initial and follow-up aneurysm occlusion rates
— id: 102600, year: 2008, vol: 29, page: 1777, stat: Journal Article,

The Potential of Flow Modification in the Treatment of Intracranial Aneurysms
Szikora, I; Nelson, PK; Berentei, Z; Kulcsar, Z; Marosfoi, M; Berez, A
2008 SEP ;14(2):77-80, Interventional neuroradiology
Background and purpose: To summarize the theoretical background and existing technical achievements of flow modification techniques in the treatment of intracranial aneurysms. The evolution of the concept of flow modification for aneurysm treatment is overviewed within the published literature on application of stents for aneurysms. The newest achievements using dedicated flow modifying devices is discussed. Reconstruction of laminar flow within intracranial arteries harboring aneurysms is feasible. Reorientation of flow using dedicated flow modifying devices is a highly effective technique in the treatment of large, broad neck, otherwise untreatable aneurysms
— id: 93277, year: 2008, vol: 14, page: 77, stat: Journal Article,

Stent-assisted Gugliemi detachable coil repair of wide-necked renal artery aneurysm using 3-D angiography
Clark, Timothy W I; Sankin, Alex; Becske, Tibor; Nelson, Peter Kim; Fox, Martin
2007 Dec-2008 Jan;41(6):528-532, Vascular & endovascular surgery
PURPOSE: To report a wide-necked renal artery aneurysm treated successfully with stent-assisted Gugliemi detachable coil occlusion, assisted by three-dimensional (3-D) angiography. CASE REPORT: A 56-year-old woman with history of hypertension presented with a 2.5-cm wide-necked saccular aneurysm involving her distal right renal artery. A balloon-expandable stent was positioned across the neck of the aneurysm and multiple Gugliemi detachable coils were deployed through a microcatheter inserted through the interstices of the stent into the aneurysm sac, guided by 3-D angiography. Follow-up 3-D angiography at 6 months revealed a patent renal artery with continued exclusion of the aneurysm and preservation of renal blood flow. CONCLUSION: Stent-assisted coil occlusion assisted by 3-D angiography is a potential renal-sparing endovascular approach to treating wide-necked renal artery aneurysms with complex vascular anatomy
— id: 75854, year: 2007, vol: 41, page: 528, stat: Journal Article,

Rapid intracranial clot removal with a new device: the alligator retriever
Kerber, C W; Wanke, I; Bernard, J Jr; Woo, H H; Liu, M W; Nelson, P K
2007 May;28(5):860-863, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Despite availability of an approved drug to treat acute cerebral ischemia, most patients with stroke do not realize a good outcome. A method that would rapidly increase or restore cerebral perfusion before irreversible cell death should improve patient outcomes. MATERIALS AND METHODS: We recently had the opportunity to treat 6 middle-aged-to-elderly patients who presented with signs and symptoms of acute cerebral ischemia, by mechanically removing their (predominantly) middle cerebral artery clots by using a new retrieval device that had been previously approved by the US Food and Drug Administration for intravascular retrieval of foreign bodies. During a 2-month period, the 6 patients were treated in 5 separate institutions. No patient had an unsuccessful attempt at clot removal. The cases were collected by personal communication with each operator. RESULTS: In all instances, use of the device resulted in rapid clot removal. Each patient had a large improvement in National Institutes of Health Stroke Scale score. Two of the 6 patients had experienced failure of another clot retrieval device, and 3 patients required no systemic thrombolytics, reducing the likelihood of one of the most feared complications of stroke therapy, intracranial hemorrhage. SUMMARY: We believe that use of this device may result in improved outcomes for patients with acute ischemic stroke. In our limited experience, it provided a rapid, safe, and effective means for achieving revascularization
— id: 102598, year: 2007, vol: 28, page: 860, stat: Journal Article,

Rapid stent-supported revascularization in acute ischemic stroke
Fitzsimmons, B-F M; Becske, T; Nelson, P K
2006 May;27(5):1132-1134, AJNR. American journal of neuroradiology
We report the case of a patient with an acute middle cerebral artery occlusion emergently revascularized with a Neuroform self-expanding stent
— id: 69021, year: 2006, vol: 27, page: 1132, stat: Journal Article,

Degree of handedness and cerebral dominance
Isaacs, Keren L; Barr, William B; Nelson, Peter Kim; Devinsky, Orrin
2006 Jun 27;66(12):1855-1858, Neurology
OBJECTIVE: To examine the relationship between the degree of handedness and hemispheric language dominance in patients with epilepsy. METHODS: The authors examined the relationship between degree of handedness and hemispheric language dominance in 174 epilepsy surgery candidates using the intracarotid amobarbital procedure and results from a modified version of the Edinburgh Handedness Inventory. RESULTS: The incidence of atypical language dominance increased linearly with the degree of left-handedness, from 9% in strong right-handers (laterality quotient [LQ] = +100) to 46% in ambidextrous individuals and 69% in strong left-handers (LQ = -100). CONCLUSIONS: The incidence of atypical language dominance depends not only on the direction but also on the degree of handedness. In addition, direction of language dominance varies with hemisphere of seizure focus and degree of handedness. A familial history of sinistrality may have an additional effect on the likelihood of atypical dominance
— id: 69637, year: 2006, vol: 66, page: 1855, stat: Journal Article,

Perfusion and diffusion tensor imaging in a patient with locked-in syndrome after neurosurgical vascular bypass and endovascular embolization of a basilar artery aneurysm: case report
Lui, Yvonne W; Law, Meng; Jafar, Jafar J; Douglas, Andrea; Nelson, Peter Kim
2006 Apr;58(4):E794-E794, Neurosurgery
OBJECTIVE AND IMPORTANCE: Locked-in syndrome is a state of preserved consciousness in the setting of quadriplegia, anarthria, and usually also includes lateral gaze palsy. It is most commonly associated with upper brainstem infarction variably sparing the third cranial nerve nucleus. There are likely many etiologies that contribute to this clinical syndrome. These are incompletely understood, and the syndrome remains a rare but devastating complication that can occur after neurosurgical and neurovascular interventions. Advanced magnetic resonance imaging techniques such as perfusion and diffusion tensor imaging may help to elucidate the mechanism behind locked-in syndrome. To the authors' knowledge, there are no reports in the literature of perfusion and diffusion tensor findings in patients with this syndrome. A postprocedural case of locked-in syndrome is described with abnormalities on perfusion and diffusion tensor imaging in the absence of any changes in conventional magnetic resonance imaging. CLINICAL PRESENTATION: A 57-year-old man who presented with acute onset headache, ataxia, and other nonspecific symptoms was found on imaging to have a giant fusiform basilar artery aneurysm. INTERVENTION: A saphenous vein graft bypass between the proximal right external carotid artery and P2 segment of the right posterior cerebral artery followed immediately by endovascular embolization of the aneurysm sac and distal left vertebral artery was performed. CONCLUSION: Postprocedural angiography demonstrated patency of the bypass graft, and diffusion weighted imaging showed no evidence for acute brainstem infarction. Nevertheless, despite technically successful procedures and the absence of abnormalities on conventional magnetic resonance imaging, the patient developed quadriplegia and anarthria and remained in a locked-in state until he expired. Abnormalities were, however, seen on both perfusion and diffusion tensor imaging, where hypoperfusion, increased mean diffusivity, and decreased fractional anisotropy were observed in the ventral brainstem. The findings suggested a disruption of pontine white matter tracts. Advanced imaging techniques may allow us to image important microstructural changes that were previously not discernable and assist in the evaluation of patients with complex neurological sequelae such as locked-in syndrome
— id: 64182, year: 2006, vol: 58, page: E794, stat: Journal Article,

Recent steps toward a reconstructive endovascular solution for the orphaned, complex-neck aneurysm
Nelson, Peter K; Sahlein, Daniel; Shapiro, Maksim; Becske, Tibor; Fitzsimmons, Brian-Fred; Huang, Paul; Jafar, Jafar J; Levy, David I
2006 Nov;59(5 Suppl 3):S77-S92, Neurosurgery
OBJECTIVE: The purposes of this article are to summarize recent developments and concerns in endovascular aneurysm therapy leading to the adjunctive use of endoluminal devices, to review the published literature on stent-supported coil embolization of cerebral aneurysms, and to describe our experience with this technique in a limited subgroup of problematic complex aneurysms over a medium-term follow-up period. METHODS: Between January 2003 and June 2004, 28 individuals among 157 patients with cerebral aneurysms we evaluated were identified as harboring aneurysms with exceptionally broad necks. Out of these 28 patients, 16 were treated with a combination of stents and detachable coils, preserving the parent artery. Recorded data included patient demographics, the clinical presentation, aneurysm location and characteristics, procedural details, and clinical and angiographic outcome. RESULTS: Over an 18-month period, 16 patients with large cerebral aneurysms additionally characterized by neck sizes between 7 and 14 mm were treated, using combined coil embolization of the aneurysm with stent reconstruction of the aneurysm neck. Thirteen out of the 16 aneurysms were occluded at angiographic reevaluation between 11 and 24 months (mean angiographic follow-up, 17.5 mo). There were no treatment-related deaths or clinically evident neurological complications. Thirteen patients experienced excellent clinical outcomes, with good outcomes in two patients and a poor visual outcome in one patient (mean clinical follow-up, 29 mo). A single technical complication occurred, involving transient nonocclusive stent-associated thrombus, which was treated uneventfully with abciximab. CONCLUSION: Stent-supported coil embolization of large, complex-neck cerebral aneurysms seems to provide superior medium-term anatomic reconstruction of the parent artery compared with historic series of aneurysms treated exclusively with endosaccular coils. In the near future, increasingly sophisticated endoluminal devices offering higher coverage of the neck defect will likely enable more definitive endovascular treatment of complex cerebral aneurysms and further expand our ability to manipulate the vascular biology of the parent artery
— id: 71410, year: 2006, vol: 59, page: S77, stat: Journal Article,

Is endovascular embolization reliable as a long-term cure for ruptured cerebral aneurysms?
Orbach, DB; Nelson, PK
2006 AUG ;2(8):420-421, Nature clinical practice. Neurology
BACKGROUND Ruptured intracranial aneurysms are associated with a high risk of permanent neurological impairment or death. Evidence suggests that detachable coils can be used to treat ruptured aneurysms safely and effectively; however, data regarding their long-term efficacy is sparse. OBJECTIVE To determine the frequency of late rebleeding of ruptured intracranial aneurysms after treatment with detachable coils. DESIGN AND INTERVENTION In this retrospective study that was conducted over 8 years, 393 consecutive patients (70% female, 30% male) with a ruptured aneurysm were treated with a detachable coil and followed up to determine the incidence of late rebleeding-defined as recurrent hemorrhage from a coiled aneurysm >1 month after coiling. Using angiography, treatment outcomes were classified as complete occlusion (98-100%), near-complete occlusion (90-98%) or incomplete occlusion (<90%). Patients were followed up clinically 6 weeks after initial discharge, and underwent angiographic follow-up at 6 months and 18 months. Further appropriate treatment was undertaken if incomplete occlusion was discovered at any time during the follow-up period. At the time of initial coiling, the mean patient age was 52.9 years (range 2581 years). In total, 63% of patients were classified as Hunt and Hess (HH) Stroke Scale I-II, 21% were HH III and 16% were HH IV-V. The majority of treated ruptured aneurysms were located in the anterior communicating artery (n = 123), the basilar tip (n = 85) or the posterior communicating artery (n = 68). OUTCOME MEASURES The primary outcome was the number of patients to experience late rebleeding after coiling of a ruptured aneurysm. A secondary outcome was the number of patients to require follow-up treatment for aneurysms. RESULTS Clinical data was available for 392 of the 393 patients. The total follow-up duration was 18,708 months, or 1,559 patient-years (mean 47.7 months, range 0-120 months). During follow-up, 70 patients (17.8%) died; deaths were attributed to various factors including subarachnoid hemorrhage (n=23), unrelated causes (n=21) and procedural complications of coiling (n = 11). Mortality associated with late rebleeding was 0.76% (n=3), giving an annual late-rebleeding mortality rate of 0.19% (95% Cl 0.04-0.60%). The late-rebleeding incidence was 1.27% (n=5), giving an annual late-rebleed rate of 0.32% (95% Cl 0.12-0.78%). The median size of the original aneurysm in patients with late rebleeding was 17 mm, compared with 8 mm in patients without late rebleeding (P=0.0017). Late rebleeding occurred in 3 of 366 (0.82%) patients with complete initial aneurysm occlusion, and 2 of 27 patients (7.41%) with incomplete initial occlusion (P=0.04). Additional treatment was required for 53 (13%) coiled aneurysms during the follow-up period. There was no significant difference in the median ages and gender ratios between patients who experienced late rebleeding and those who did not. CONCLUSION Coiling of ruptured aneurysms is associated with a very low rate of rebleeding. Angiographic follow-up reveals incomplete initial occluded aneurysms that might require additional treatment
— id: 66449, year: 2006, vol: 2, page: 420, stat: Journal Article,

Endovascular treatment of spinal cord arteriovenous malformations
Veznedaroglu, Erol; Nelson, Peter K; Jabbour, Pascal M; Rosenwasser, Robert H
2006 Nov;59(5 Suppl 3):S202-S209, Neurosurgery
Spinal cord arteriovenous malformations are rare lesions that represent one-tenth of the brain arteriovenous malformations. Depending on their location and relationship to the dura, these lesions are divided into four categories. Their clinical manifestations may vary from mild symptoms to severe motor deficits. Spinal angiography remains the 'gold standard' for diagnosing spinal cord vascular lesions. Although the type of shunting remains difficult to determine by the magnetic resonance imaging, it is well analyzed by spinal angiography. The cure of the shunting is not by itself a therapeutic goal, but the objective is the creation of a new hemodynamic equilibrium between the lesion and the spinal cord to decrease the risk of hemorrhage and prevent the progression of the spinal cord ischemia. The endovascular tools seem to be a reasonable therapeutic option for the treatment of the majority of the spinal cord arteriovenous malformations
— id: 107799, year: 2006, vol: 59, page: S202, stat: Journal Article,

Flow changes caused by the sequential placement of stents across the neck of sidewall cerebral aneurysms
Canton, Gador; Levy, David I; Lasheras, Juan C; Nelson, Peter K
2005 Nov;103(5):891-902, Journal of neurosurgery
OBJECT: The goal of this study was to quantify the reduction in velocity, vorticity, and shear stresses resulting from the sequential placement of stents across the neck of sidewall cerebral aneurysms. METHODS: A digital particle image velocimetry (DPIV) system was used to measure the pulsatile velocity field within a flexible silicone sidewall intracranial aneurysm model and at the aneurysm neck-parent artery interface in this model. The DPIV system is capable of providing an instantaneous, quantitative two-dimensional measurement of the velocity vector field of 'blood' flow inside the aneurysm pouch and the parent vessel, and its changes at varying stages of the cardiac cycle. The corresponding vorticity and shear stress fields are then computed from the velocity field data. Three Neuroform stents (Boston Scientific/Target), each with a strut thickness between 60 and 65 microm, were subsequently placed across the neck of the aneurysm model and measurements were obtained after each stent had been placed. The authors measured a consistent decrease in the values of the maximal averaged velocity, vorticity, and shear stress after placing one, two, and three stents. Measurements of the circulation inside the sac demonstrated a systematic reduction in the strength of the vortex due to the stent placement. The decrease in the magnitude of the aforementioned quantities after the first stent was placed was remarkable. Placement of two or three stents led to a less significant reduction than placement of the first stent. CONCLUSIONS: The use of multiple flexible intravascular stents effectively reduces the strength of the vortex forming in an aneurysm sac and results in a decrease in the magnitude of stresses acting on the aneurysm wall
— id: 107800, year: 2005, vol: 103, page: 891, stat: Journal Article,

[Chemokine directed homing of transplanted adult stem cells in wound healing and tissue regeneration]
Huss, R; von Luttichau, I; Lechner, S; Notohamiprodjo, M; Seliger, C; Nelson, P
2004 ;88:170-173, Verhandlungen der Deutschen Gesellschaft fur Pathologie
A major challenge in stem cell biology is to study the underlying mechanisms of tissue specific homing and differentiation. Recent results suggest that bone marrow derived stem cells can give rise to multiple cell types. Because chemokines and chemokine receptors are associated with development, differentiation and homing of immune cells, we undertook efforts to study the chemokine receptor expression profile of human adult stem cells to identify their potential role in tissue specific homing prior to transdifferentiation. Using human bone marrow-derived stem cell lines, we could demonstrate functional chemokine receptor expression of various chemokine receptors. The expression of CXCR5 and CCR7, associated with secondary lymphoid organ homing as well as CXCR4 and CCR10, involved in organ specific homing and CXCR3, CCR5 and CCR1, which are involved in inflammation events, suggested a role of chemokine receptors in tissue specific homing of stem cells. To proof the specific homing of stem cells in vivo, we used murine stem cell lines, stably introduced green fluorescent protein under control of CMV promotor into the cells and injected them intravenously into mice. We demonstrate the homing of these stem cells to lymphnode and thymus as well as mucosal tissue, while stem cells home exclusively to a site of lesion during wound healing and tissue regeneration. Our data suggest that chemokine biology may play a pivotal role in the homing of stem cells to specific tissues and niches prior to (trans)differentiation, while the homing changes during tissue damage and other adequate lesions
— id: 128705, year: 2004, vol: 88, page: 170, stat: Journal Article,

Use of a wedged microcatheter for curative transarterial embolization of complex intracranial dural arteriovenous fistulas: indications, endovascular technique, and outcome in 21 patients
Nelson, Peter Kim; Russell, Stephen M; Woo, Henry H; Alastra, Anthony J G; Vidovich, Danko V
2003 Mar;98(3):498-506, Journal of neurosurgery
OBJECT: The aim of this study was to describe the application of a novel transarterial approach to curative embolization of complex intracranial dural arteriovenous fistulas (DAVFs). This technique is particularly useful in patients harboring high-grade DAVFs with direct cortical venous drainage or for whom transvenous coil embolization is not possible because of limited sinus venous access to the fistula site due to thrombosis or stenotic changes. METHODS: Twenty-three DAVFs in 21 patients were treated using a transarterial N-butyl cyanoacrylate (NBCA) embolization technique with the aid of a wedged catheter. In all patients, definitive treatment involved two critical steps: 1) a microcatheter was wedged within a feeding artery, establishing flow-arrest conditions within the catheterized vessel distal to the microcatheter tip; and 2) NBCA was injected under these resultant flow-arrest conditions across the pathological arteriovenous connection and into the immediate draining venous apparatus, definitively occluding the fistula. Patient data were collected in a retrospective manner by reviewing office and inpatient charts and embolization reports, and by directly analyzing all procedural and diagnostic angiograms. Eight patients presented with the principal complaint of tinnitus/bruit, five with intracranial hemorrhage, four with cavrnous sinus syndrome, and one each with seizures, ataxia, visual field loss, and hiccups. The parent (recipient) venous structure of the DAVFs in this study included 11 leptomeningeal veins, eight transverse/sigmoid sinuses, three cavernous sinuses, and one sphenoparietal sinus. The NBCA permeated the arteriovenous shunt, perifistulous network, and proximal draining vein in all DAVFs. Occlusion was confirmed on postembolization angiography studies. No complication occurred in any patient in this series. There has been no recurrence during a mean follow up of 18.7 months (range 2-46 months). CONCLUSIONS: Transarterial NBCA embolization with the aid of a wedged catheter in flow-arrest conditions is a safe and an effective treatment for intracranial DAVFs
— id: 39265, year: 2003, vol: 98, page: 498, stat: Journal Article,

Transarterial Wedged-catheter, Flow-arrest, N-butyl Cyanoacrylate Embolization of Three Dural Arteriovenous Fistulae in a Single Patient
Russell, S M; Woo, H H; Nelson, P K
2003 Sep 30;9(3):283-290, Interventional neuroradiology
Summary: The pathogenesis of dural arteriovenous fistulas (DAVFs) is currently unknown, with multiple DAVFs being rare. For patients with limited venous access secondary to sinus thrombosis, or for patients where parent sinus occlusion would not be tolerated, transvenous embolization may not be possible and other treatment methods must be considered. A 69-year-old female patient with a two-year history of progressive headaches, memory loss, and unsteady gait underwent cerebral angiography that revealed three separate DAVFs with congested cortical venous drainage overlying both frontal lobes. Using an application of a transarterial wedged-catheter, flow-arrest technique, N-butyl cyanoacrylate was deposited across all three pathologic arteriovenous connections providing a definitive cure. Transarterial NBCA embolization may provide curative treatment of DAVFs, and is of particular utility in situations where access to the draining venous structures is limited
— id: 110670, year: 2003, vol: 9, page: 283, stat: Journal Article,

Interactive use of cerebral angiography and magnetoencephalography in arteriovenous malformations: technical note
Kamiryo, Toshifumi; Cappell, Joshua; Kronberg, Eugene; Woo, Henry H; Jafar, Jafar J; Llinas, Rodolfo R; Nelson, Peter K
2002 Apr;50(4):903-910, Neurosurgery
OBJECTIVE: To minimize the risks associated with treating cortical cerebral arteriovenous malformations (AVMs), we developed a technique combining functional imaging and cerebral angiography. The functional loci obtained by performing magnetoencephalography (MEG) are projected onto stereoscopic pairs of a stereotactically derived digital subtraction angiogram. The result is a simultaneous three-dimensional perspective of the angioarchitecture of an AVM and its relationship to the sensorimotor cortex. METHODS: Eight patients underwent multimodality brain imaging, including magnetic resonance imaging, functional mapping via MEG, and stereotactic angiography using a modified Compass fiducial system (Compass International, Rochester, MN). The coordinates derived by performing MEG were superimposed onto stereotactic, stereoscopic, angiographic pairs using custom-made distortion correction and coordinate transfer software. RESULTS: The magnetoencephalographic angiogram allowed simultaneous viewing of the angioarchitecture of the AVM nidus, the feeding vessels, and the draining veins and their relationship to the normal cerebral vasculature and functional cortex. This imaging technique was particularly valuable in identifying en passant vessels that supplied functional cortex and was used during the treatment of these lesions. CONCLUSION: The techniques of MEG and cerebral angiography were combined to provide simultaneous viewing of both modalities in a three-dimensional perspective. This technique can aid in risk stratification in the management of patients with cerebral AVMs. In addition, this technique can facilitate the selective targeting of vessels, thus potentially reducing the risks associated with embolization of these formidable lesions
— id: 36682, year: 2002, vol: 50, page: 903, stat: Journal Article,

Images in clinical medicine. Mycotic aneurysms
Lynfield, Joshua; Nelson, Peter Kim
2002 Dec 19;347(25):2030-2030, New England journal of medicine
— id: 43232, year: 2002, vol: 347, page: 2030, stat: Journal Article,

Neurological deterioration after coil embolization of a giant basilar apex aneurysm with resolution following parent artery clip ligation. Case report and review of the literature
Russell, Stephen M; Nelson, P Kim; Jafar, Jafar J
2002 Sep;97(3):705-708, Journal of neurosurgery
The authors present the case of a patient who suffered from progressive cranial nerve dysfunction, radiographically documented brainstem compression, and peduncular hallucinosis after undergoing endosaccular coil placement in a giant basilar apex aneurysm. Symptom resolution was achieved following clip ligation of the basilar artery. The pathogenesis of aneurysm mass effect due to coil placement is discussed and the pertinent literature is reviewed
— id: 36680, year: 2002, vol: 97, page: 705, stat: Journal Article,

Hemispheric influence on autonomic modulation and baroreflex sensitivity
Hilz MJ; Dutsch M; Perrine K; Nelson PK; Rauhut U; Devinsky O
2001 May;49(5):575-584, Annals of neurology
Several studies suggest hemispheric lateralization of autonomic cardiovascular control. There is controversy regarding which hemisphere dominates sympathetic or parasympathetic activity. Hemispheric influences on baroreflex sensitivity (BRS) have not yet been evaluated. To determine hemispheric autonomic control in epilepsy patients, we assessed cardiovascular and baroreflex modulation before and during hemispheric inactivation. For 15 patients with drug-refractory epilepsy, we analyzed autonomic heart rate (HR) and blood pressure (BP) modulation and BRS before and during left and right intracarotid amobarbital procedure (IAP). After Blackman-Tukey spectral analysis, we calculated the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: 0.15-0.5 Hz) power of HR and BP as well as BRS as the LF transfer function gain between BP and HR. Right hemispheric inactivation induced a significant decrease of BP and an increase of HF power of HR and BP (p < 0.05). Left inactivation increased HR, BP, and LF power of both signals and decreased BRS by nearly 30% (p < 0.05). The results confirm previous IAP studies showing sympathetic lateralization in the right hemisphere and, moreover, demonstrate parasympathetic predominance and up-regulation of BRS in the left hemisphere. In epilepsy patients, unilateral electrical activity might derange autonomic balance between both hemispheres and contribute to cardiovascular dysregulation and sudden fatalities
— id: 20660, year: 2001, vol: 49, page: 575, stat: Journal Article,

De novo aneurysm formation after stereotactic radiosurgery of a residual arteriovenous malformation: case report
Huang PP; Kamiryo T; Nelson PK
2001 Aug;22(7):1346-1348, AJNR. American journal of neuroradiology
We report a case of a 19-year-old woman who underwent radiosurgical treatment of a residual arteriovenous malformation. Nine months after treatment, repeat angiography revealed a de novo paranidal aneurysm that was treated endovascularly. We postulate that changes in flow dynamics or vessel integrity after radiosurgery contributed to the formation of her de novo aneurysm
— id: 26704, year: 2001, vol: 22, page: 1346, stat: Journal Article,

A stereotactic device for experimental rat and mouse irradiation using gamma knife model B--technical note
Kamiryo T; Han K; Golfinos J; Nelson PK
2001 ;143(1):83-87, Acta neurochirurgica
BACKGROUND: For radiobiological experiments using the Gamma Knife model B, we constructed a stereotactic device to irradiate rat and mouse brains and verify the absorbed dose at the target using thermoluminescence dosimetry and a head phantom. METHODS: Our stereotactic device is primarily designed for rats using the fixation principles of a stereotactic atlas. A head-fixation adapter for a mouse was constructed to enable targeted irradiation of mouse brains. We built simple phantoms to simulate rat and mouse heads. We placed thermoluminescent dosimeters at various positions on the phantom for dose measurements. Dose planning employed the Leksell Gamma Plan version 4.11 software, assuming a spherical skull geometry for all calculations. FINDINGS: The measurements demonstrated that the actual absorbed dose agreed with our calculations within the errors of thermoluminescence dosimetry and the accuracy of our irradiation technique and dose calculations. INTERPRETATION: This device provides an accurate method for irradiating rat and mouse brains using the Gamma Knife model B
— id: 20676, year: 2001, vol: 143, page: 83, stat: Journal Article,

Balloon-assisted coil embolization of wide-necked aneurysms of the internal carotid artery: medium-term angiographic and clinical follow-up in 22 patients
Nelson PK; Levy DI
2001 Jan;22(1):19-26, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: The management of broad-necked cerebral aneurysms by Guglielmi detachable coils (GDCs) is technically challenging owing to a variety of factors, including difficulty in defining the aneurysm/parent vessel interface angiographically and problems in achieving complete occlusion, later predisposing the aneurysm to regrowth/recanalization. We sought to determine whether the use of intraluminal balloons to remodel the parent vessel/aneurysm interface during GDC embolization would provide a safe means of improving the efficacy of endovascular treatment of broad-necked aneurysms. METHODS: Twenty-two saccular aneurysms of the internal carotid artery were treated with GDCs by using balloon remodeling techniques. All aneurysms were characterized by wide necks or were small with unfavorable neck/fundus ratios and required balloon assistance for coil embolization. Patients were followed up both clinically and angiographically. RESULTS: By using a microcatheter-mounted nondetachable balloon to provide a temporary barrier across the aneurysmal neck, we were able to deploy GDCs safely within a variety of aneurysms. Among the 22 patients treated, aneurysmal occlusion on follow-up angiography (mean, 19 months) was found in 17 of 20 patients (two patients died and no follow-up studies were available). Observed or suspected thromboembolic events occurred in four of 22 patients, resulting in one permanent deficit. Twenty of the 22 patients had good to excellent clinical outcomes. CONCLUSION: Although balloon-assisted coiling of cerebral aneurysms requires manipulation of a second microcatheter and an inflatable balloon, increasing its technical complexity, we believe that this method has utility in treating broad-necked aneurysms and small aneurysms that are otherwise suboptimally managed by conventional GDC deployment
— id: 26818, year: 2001, vol: 22, page: 19, stat: Journal Article,

Imaging normal and abnormal brain development: new perspectives for child psychiatry
Rapoport JL; Castellanos FX; Gogate N; Janson K; Kohler S; Nelson P
2001 Jun;35(3):272-281, Australian & New Zealand journal of psychiatry
OBJECTIVE: The availability of non-invasive brain imaging permits the study of normal and abnormal brain development in childhood and adolescence. This paper summarizes current knowledge of brain abnormalities of two conditions, attention deficit hyperactivity disorder (ADHD) and childhood onset schizophrenia (COS), and illustrates how such findings are bringing clinical and preclinical perspectives closer together. METHOD: A selected review is presented of the pattern and temporal characteristics of anatomic brain magnetic resonance imaging (MRI) studies in ADHD and COS. These results are discussed in terms of candidate mechanisms suggested by studies in developmental neuroscience. RESULTS: There are consistent, diagnostically specific patterns of brain abnormality for ADHD and COS. Attention deficit hyperactivity disorder is characterized by a slightly smaller (4%) total brain volume (both white and grey matter), less-consistent abnormalities of the basal ganglia and a striking (15%) decrease in posterior inferior cerebellar vermal volume. These changes do not progress with age. In contrast, patients with COS have smaller brain volume due to a 10% decrease in cortical grey volume. Moreover, in COS there is a progressive loss of regional grey volume particularly in frontal and temporal regions during adolescence. CONCLUSIONS: In ADHD, the developmental pattern suggests an early non-progressive 'lesion' involving neurotrophic factors controlling overall brain growth and selected dopamine circuits. In contrast, in COS, which shows progressive grey matter loss, various candidate processes influencing later synaptic and dendritic pruning are suggested by human post-mortem and developmental animal studies
— id: 27614, year: 2001, vol: 35, page: 272, stat: Journal Article,

Visual loss from arterial steal in patients with maxillofacial arteriovenous malformation
Andracchi S; Kupersmith MJ; Nelson PK; Slakter JS; Setton A; Berenstein A
2000 Apr;107(4):730-736, Ophthalmology
OBJECTIVE: To determine whether an arterial 'steal' from the ophthalmic artery accounts for the ocular manifestations associated with maxillofacial arteriovenous malformation (AVM) outside the orbit. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Seven patients with maxillofacial AVM who had been previously treated, unsuccessfully, with proximal ligation of the supplying external carotid artery branches were evaluated clinically and by superselective cerebral angiography. No cases had intraorbital arteriovenous shunting or abnormal venous drainage to the orbit. INTERVENTION: Endovascular embolization. MAIN OUTCOME MEASURES: Signs and symptoms of ocular ischemia were correlated with findings on cerebral/orbital angiography. RESULTS: Four of seven patients had signs of ocular ischemia. By selective angiography, these four patients were found to have a significant ophthalmic artery supply to the AVM. In contrast, the three patients without signs of ocular ischemia had minimal or no ophthalmic artery supply to the AVM. CONCLUSIONS: When the ophthalmic arterial blood supply is recruited, ophthalmic artery 'steal' phenomenon occurs in patients with maxillofacial AVMs that do not directly involve the orbit. This mechanism appears to be the cause of ocular ischemia. It is possible that this 'steal' is precipitated or worsened by previous surgical proximal ligation of external carotid arterial branches that are potential collaterals with the ophthalmic artery but fail to occlude the arteriovenous (AV) shunts
— id: 11748, year: 2000, vol: 107, page: 730, stat: Journal Article,

Familial arteriovenous malformations in siblings
Kamiryo T; Nelson PK; Bose A; Zalzal P; Jafar JJ
2000 Mar;53(3):255-259, Surgical neurology
BACKGROUND: Familial arteriovenous malformations (AVMs) of the brain are rare. We present two sisters with the same parents who harbored AVMs that were successfully treated. METHODS: The elder sister presented with a unilateral migrainous type of headache overlying the right parietal area. The younger one suffered from exercise-induced headaches. Both were neurologically intact. Magnetic resonance imaging scans of the brain and cerebral angiography delineated the lesions. Both sisters underwent endovascular embolization followed by surgical resection. RESULTS: Postoperatively, aside from a left inferior quadrantanopsia in the elder sister, both were neurologically intact. CONCLUSIONS: We report the rare occurrence of familial AVMs in two siblings and review the literature of 14 reports. No genetic predisposition was found
— id: 11741, year: 2000, vol: 53, page: 255, stat: Journal Article,

Cerebral vasculopathy secondary to leptomeningeal gliomatosis: angiography
Masters LT; Miller DC; Nelson PK
2000 Feb;42(2):139-141, Neuroradiology
We describe a young woman with a glioblastoma multiforme in whom angiography showed multiple intracranial stenoses. The resected tumour was found to be invading cerebral vessels
— id: 11845, year: 2000, vol: 42, page: 139, stat: Journal Article,

Wada testing in pediatric patients by use of propofol anesthesia [In Process Citation]
Masters LT; Perrine K; Devinsky O; Nelson PK
2000 Aug;21(7):1302-1305, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Wada testing may provide important information for surgical planning in pediatric patients with medically refractory epilepsy, but it is often not used because of the difficulties in performing the angiographic portion of the procedure in conscious children. We reviewed our experience using propofol, a short-acting IV administered anesthetic agent, for pediatric patients undergoing Wada testing. METHODS: In a retrospective review of Wada tests performed on patients younger than 18 years, we identified 24 cases in which propofol anesthesia was used. We reviewed the medical records of these patients, with particular reference to dose of propofol, physiological parameters during anesthesia, and adequacy of neuropsychological testing after emergence from anesthesia. RESULTS: Patients ranged in age from 6 to 16 years (mean age, 12.5 years). Propofol induced mild reductions in blood pressure (12.4% for systolic and 13.9% for diastolic blood pressure) and heart rate (mean reduction of 4.7%), which did not require specific treatment in any patient. Recovery from anesthesia was smooth and rapid, allowing initiation of Wada testing within 15 to 25 minutes of cessation of propofol. Wada testing was successfully accomplished in all patients. CONCLUSION: Propofol provided rapid induction of anesthesia, was administered without endotracheal intubation, and did not cause substantial changes in cardiorespiratory parameters. Propofol anesthesia allowed controlled angiography among patients as young as 6 years and did not interfere with neuropsychological testing
— id: 11535, year: 2000, vol: 21, page: 1302, stat: Journal Article,

Angiographic abnormalities in progressive multifocal leukoencephalopathy: an explanation based on neuropathologic findings
Nelson PK; Masters LT; Zagzag D; Kelly PJ
1999 Mar;20(3):487-494, AJNR. American journal of neuroradiology
BACKGROUND AND PURPOSE: Progressive multifocal leukoencephalopathy (PML) is typically occult at angiography and fails to enhance on MR images. After observing angiographic abnormalities characterized by arteriovenous shunting and pathologic parenchymal blush in patients with AIDS-related PML, often in the absence of contrast enhancement on MR images, we hypothesized that there might be distinct changes in the cerebral microvasculature that account for the reduction in vascular transit time (arteriovenous shunting) in the absence of blood-brain barrier dysfunction. METHODS: The imaging studies and neuropathologic specimens of six patients with biopsy-proved PML were reviewed retrospectively. In all patients contrast-enhanced MR imaging and CT, followed by cerebral angiography, were performed before stereotactically directed biopsy. The angiograms were evaluated for the presence of vascular displacement, pathologic parenchymal blush, arteriovenous shunting, and neovascularity. The CT and MR studies were reviewed for the presence of enhancement of the PML lesions. Biopsy specimens were examined for the presence of necrosis, perivascular inflammation, and neovascularity. RESULTS: All patients had oligodendrocytic intranuclear inclusions diagnostic of PML, together with perivascular inflammation and neovascularity to a varying extent; no other neuropathologic processes were identified. Angiographic abnormalities, characterized by a pathologic parenchymal blush and arteriovenous shunting, were identified in four of the six patients. In only one of these cases, however, was abnormal enhancement identified on cross-sectional imaging studies (MR and CT), and this patient had florid perivascular inflammatory infiltrates histologically. CONCLUSION: The pathologic parenchymal blush and arteriovenous shunting seen angiographically in some patients with PML reflect small-vessel proliferation and perivascular inflammatory changes incited by the presence of the JC virus in infected oligodendrocytes
— id: 6100, year: 1999, vol: 20, page: 487, stat: Journal Article,

Hemispheric inactivation during intracarotid amobarbital test suggests right hemispheric lateralization of sympathetic cardiac control
Hilz, MJ; Devinsky, O; Duetsch, M; Perrine, K; Rauhut, U; Nelson, PK
1998 SEP ;44(3):M35-M35, Annals of neurology
— id: 104276, year: 1998, vol: 44, page: M35, stat: Journal Article,

A dissecting aneurysm of the posteroinferior cerebellar artery: case report
Jafar JJ; Kamiryo T; Chiles BW; Nelson PK
1998 Aug;43(2):353-356, Neurosurgery
OBJECTIVE AND IMPORTANCE: We present a patient who experienced a subarachnoid hemorrhage secondary to a dissecting aneurysm of the right posteroinferior cerebellar artery (PICA). The use of an encircling clip in treating the aneurysm while preserving supply to brain stem perforators originating near the dissecting segment and the distal PICA territory was key in the operative management. CLINICAL PRESENTATION: A 48-year-old patient with a history of hypertension presented with subarachnoid hemorrhage confirmed by computed tomography of the brain. Successive cerebral angiography revealed a dynamic change in the configuration of the dissection, with expansion of the associated focal ectasia. OPERATIVE MANAGEMENT: At surgery, three brain stem perforators adjacent to the aneurysm were visualized. The dissecting segment was reconstructed with an encircling Sundt clip and muslin wrap, which preserved the flow through the PICA and brain stem perforators. CONCLUSION: A patient suffering from a dissecting PICA aneurysm and subarachnoid hemorrhage was successfully treated with direct surgical reconstruction of the parent artery, sparing the perforators to the medulla
— id: 7619, year: 1998, vol: 43, page: 353, stat: Journal Article,

Gadolinium-enhanced 3D MRA of the aortic arch vessels in the detection of atherosclerotic cerebrovascular occlusive disease
Krinsky G; Maya M; Rofsky N; Lebowitz J; Nelson PK; Ambrosino M; Kaminer E; Earls J; Masters L; Giangola G; Litt A; Weinreb J
1998 Mar-Apr;22(2):167-178, Journal of computer assisted tomography
PURPOSE: Our goal was to evaluate non-breath-hold Gd-enhanced 3D MR angiography (MRA) for the detection of atherosclerotic occlusive disease of the aortic arch vessels and to compare image quality with two breath-hold techniques. METHOD: One hundred sixty consecutive patients with known or clinically suspected atherosclerotic cerebrovascular occlusive disease underwent Gd-enhanced 3D MRA of the aortic arch and great vessels. One hundred twenty-six examinations were performed with the body coil after infusion of 40 ml of Gd-DTPA; 89 of these were performed without breath-holding and 37 were acquired during suspended respiration. Thirty-four examinations were performed in a body phased-array coil with breath-holding, a timing examination, and 20 ml of contrast agent by manual (n = 17) or power (n = 17) injection. Images were evaluated for the presence of blurring and ghosting artifacts and venous enhancement. Of the 27 patients who underwent non-breath-hold MRI and digital subtraction angiography (DSA), two readers blinded to the DSA results retrospectively evaluated the MRA examinations for the presence of occlusive disease of the innominate, carotid, subclavian, and vertebral arteries. DSA correlation was not evaluated for the 71 breath-hold studies. RESULTS: Sensitivity and specificity for arch vessel occlusive disease with non-breath-hold MRA were 38 and 94% for Reader A and 38 and 95% for Reader B. Breath-holding significantly reduced blurring and ghosting artifacts (p < 0.001) when compared with non-breath-hold imaging, and use of 20 ml of contrast medium, with a timing examination, resulted in significantly less venous enhancement than seen with 40 ml (p < 0.001). CONCLUSION: Non-breath-hold Gd-enhanced 3D MRA is insensitive for detecting arch vessel occlusive disease. Breath-hold imaging, in conjunction with a timing examination and a lower dose of contrast agent, improves image quality, but further studies are needed to assess diagnostic accuracy
— id: 7635, year: 1998, vol: 22, page: 167, stat: Journal Article,

Pre-operative Angiography and Embolisation of Petroclival Meningiomas
Masters, L T; Nelson, P K
1998 Sep 30;4(3):209-221, Interventional neuroradiology
Summary: We reviewed our experience of 15 patients with petroclival meningiomas who underwent pre-operative angiography, 11 of whom were embolised in the same session. We analysed our cases to evaluate the variations in vascular supply to these tumours, their potential for embolisation, and the techniques used for their devascularization; as well as associated MRl findings. The petroclival region is vascularised by the basal tentorial arcade. Petroclival meningiomas derive their blood supply from the ICA and ECA branches which form this network, and may also parasitize supply from the vertebrobasilar system. ICA (meningohypophyseal trunk) supply was present in all our patients, and 93% also had ECA contributions (basal tentorial branches of the middle and accessory meningeal arteries, the ascending pharyngeal artery, the artery of foramen rotundum and transmastoid branches of the occipital artery). 47% had pial supply from the vertebrobasilar system. The ECA supply was partly or completely embolised in each of the 11 patients, and the meningohypophyseal contribution in one; there were no complications. Pre-operative angiographic assessment of patients with petroclival meningiomas provides important information for determining the surgical approach, and when combined with embolisation may facilitate a more complete resection of these surgically challenging lesions
— id: 111545, year: 1998, vol: 4, page: 209, stat: Journal Article,

Neurointerventional management of intracranial aneurysms
Nelson PK
1998 Oct;9(4):879-895, Neurosurgery clinics of North America
For many patients with cerebral aneurysms, endovascular therapy offers an acceptable alternative to aneurysm surgery. These neurointerventional methods are broadly classified as deconstructive or reconstructive procedures, depending on whether the parent vessel is preserved in treating the aneurysm. Results to date suggest that appropriately selected patients may be treated successfully with low technical morbidity and mortality. Whereas certain shortcomings are evident, developing technology has expanded the spectrum of aneurysms amenable to endovascular treatment and improved the effectiveness of such management
— id: 7413, year: 1998, vol: 9, page: 879, stat: Journal Article,

Interhemispheric memory transfer in the intracarotid amobarbital procedure
Perrine K; Donofrio N; Devinsky O; Gershengorn J; Luciano DJ; Nelson PK
1998 Jan;11(1):8-11, Neuropsychiatry neuropsychology & behavioral neurology
The authors examined interhemispheric memory transfer in 32 patients with lateralized temporal lobe complex partial epilepsy (15 right onsets, 17 left onsets). Visually presented verbal, nonverbal, and two types of dually encodable stimuli were displayed during amobarbital anesthesia, and recognition memory was tested with verbal and nonverbal (pointing) response modalities. No relationship was found between the material specificity of stimuli and response modality. The only significant findings were for poorer recognition memory after injection of the hemisphere contralateral to the seizure focus. Visual information presented predominantly to one hemisphere during anesthesia is available to the other hemisphere for recognition memory on clearing
— id: 7741, year: 1998, vol: 11, page: 8, stat: Journal Article,

Arteriovenous fistula of the scalp secondary to punch autograft hair transplantation: angioarchitecture, histopathology, and endovascular and surgical therapy
Davis AJ; Nelson PK
1997 Jul;100(1):242-249, Plastic & reconstructive surgery
Arteriovenous fistula of the scalp secondary to punch autograft technique is a relatively uncommon occurrence, similar to traumatic scalp arteriovenous fistulas from other causes. A pulsatile subcutaneous mass with an associated thrill or bruit and symptoms including pain or headache is a common presentation. Angiography is required for full diagnostic evaluation. Angioarchitecture may appear complex, even with a single-hole fistula. Super-selective angiography and embolization facilitate surgery and provide essential information regarding angioarchitecture. Complete excision of the lesion is curative. Identification and resection of the draining vein is mandatory to ensure a complete resection. The lesion may extend across traditional anatomic planes. Ligation of proximal feeding arteries is inadequate and potentially harmful. Histopathology of the traumatic arteriovenous fistula may appear similar to that of an arteriovenous malformation. Acquired arteriovenous fistulas and congenital arteriovenous malformations are markedly similar in their ultimate histopathology, angioarchitecture, angiographic appearance, hemodynamics, and treatment requirements. They should be considered to represent a spectrum of the same disease state rather than discrete entities
— id: 7138, year: 1997, vol: 100, page: 242, stat: Journal Article,

Serial recovery of language during the intracarotid amobarbital procedure
Ravdin LD; Perrine K; Haywood CS; Gershengorn J; Nelson PK; Devinsky O
1997 Mar;33(2):151-160, Brain & cognition
There is considerable variability among epilepsy centers in the methods and interpretations of the intracarotid amobarbital procedure. Prominent among these differences is the determination of language representation and assessment of language functions. Some centers rely on speech arrest following amobarbital injection as a marker for language representation, whereas other centers examine verbal output for the presence of aphasic errors. The present study assessed the pattern of language recovery following amobarbital injection in epilepsy patients who were candidates for temporal lobectomy. Language recovery from dominant hemisphere injection (left or right) followed a stereotypical progression, with 71.8% of patients showing return of vocalization followed by return of naming and comprehension. Repetition deficits with paraphasic errors persisted the longest (mean = 12'30'), with a conduction aphasia persisting after the acute global aphasia resolved. Although two patients interpreted as left hemisphere language dominant were mute following right hemisphere injection, all language functions were intact immediately upon resumption of vocalization and they showed no other signs of aphasia such as paraphasias or anomia. Possible explanations for serial language recovery and persistent conduction aphasia are discussed. These findings have significant implications for the determination of cerebral language dominance
— id: 34435, year: 1997, vol: 33, page: 151, stat: Journal Article,

Angiographic findings associated with intra-axial intracranial tumors
Masters LT; Pryor JC; Nelson PK
1996 Aug;6(3):739-749, Neuroimaging clinics of North America
Although computed tomography and, more recently, magnetic resonance imaging, have supplanted pneumoencephalography and angiography in the initial evaluation of patients with suspected intracranial neoplasms, angiography may still have an important role in the diagnosis and management of such individuals. It can define normal arterial and venous anatomy (important information in planning surgical approaches to some lesions), show vascular abnormalities associated with intracranial tumors, evaluate the integrity of the collateral circulation, incorporate functional testing for eloquent brain in the vicinity of a lesion, and be used in conjunction with the administration of intra-arterial chemotherapy
— id: 12563, year: 1996, vol: 6, page: 739, stat: Journal Article,

Vertebrospinal angiography in the evaluation of vertebral and spinal cord disease
Nelson PK; Setton A; Berenstein A
1996 Aug;6(3):589-605, Neuroimaging clinics of North America
Spinal angiography is an infrequently performed radiologic procedure requiring much skill and knowledge for its proper application. Most commonly, spinal angiography is used in the diagnosis of spinal arteriovenous malformations and in the delineation of vascular tumors of the spinal cord. Less usual indications may include preoperative evaluation of the spinal cord vasculature prior to surgeries involving the descending thoracic aorta or ventrolateral approaches to the spine, particularly in patients undergoing repeat operations. Spinal angiography should address three crucial considerations for the surgeon or neurointerventionalist: (1) the exact location and anatomic configuration of the lesion, (2) the vascularity of a lesion and identification of all feeding and draining vessels, and (3) depiction of the regional vascular anatomy of the spinal cord in relation to the lesion. Considering the relatively longer length of the procedure, larger contrast volumes, and increased complexity (as measured by catheter exchanges required) of spinal angiography, however, certain angiographic techniques (e.g., digital subtraction angiography, the use of general anesthesia, or placement of a groin sheath to facilitate catheter exchanges) and the use of low osmolality contrast agents should be considered to improve the quality of the examination while reducing risk
— id: 12565, year: 1996, vol: 6, page: 589, stat: Journal Article,

Cerebral angiography
Nelson, Peter Kim; Kricheff, Irvin I
Philadelphia : W.B. Saunders, 1996,
— id: 606, year: 1996, vol: , page: , stat: ,

Complications of diagnostic cerebral angiography and tips on avoidance
Pryor JC; Setton A; Nelson PK; Berenstein A
1996 Aug;6(3):751-758, Neuroimaging clinics of North America
— id: 12562, year: 1996, vol: 6, page: 751, stat: Journal Article,

High-dose administration of nonionic contrast media: a retrospective review [see comments]
Rosovsky MA; Rusinek H; Berenstein A; Basak S; Setton A; Nelson PK
1996 Jul;200(1):119-122, Radiology
PURPOSE: To assess the safety of high-dose nonionic contrast media (CM) during a single radiologic procedure. MATERIALS AND METHODS: From November 1991 to August 1995, 255 high-dose angiographic procedures were performed in 228 patients with normal serum creatinine (SCr) levels (< or = 1.6 mg/dL [141 mumol/L]). All patients received 250-800 mL low-osmolarity CM (300 mg iodine per milliliter). Pre- and postprocedure SCr levels were assessed. Urine output was measured daily in the 75 patients who received more than 400 mL CM. With linear regression analysis, a dose-related elevation in SCr levels was calculated. RESULTS: No patient developed abnormal SCr levels (> 1.6 mg/dL [141 mumol/L]) as a result of the CM. Among the patients who received more than 400 mL, none developed oliguria over the first 36 hours. With follow-up up to 3 years, no patient experienced delayed clinical renal failure. In 11 (4.3%) patients, the SCr levels increased more than 25%, but all increases were within expected limits (chi 2 analysis). Linear regression analysis revealed a 0.015 mg/dL (1 mumol/L) increase in SCr levels per 100 mL CM. CONCLUSION: Intravenous administration of high-dose low-osmolarity iodinated CM appears safe in patients without renal dysfunction or other underlying risk factors, in doses as large as 800 mL (300 mg iodine per milliliter)
— id: 7251, year: 1996, vol: 200, page: 119, stat: Journal Article,

Angiography of cerebral aneurysms
Setton A; Davis AJ; Bose A; Nelson PK; Berenstein A
1996 Aug;6(3):705-738, Neuroimaging clinics of North America
Magnetic resonance and computed tomographic angiography have been increasingly applied to the study of disease affecting the cerebral vasculature. Despite these advances, however, conventional cerebral angiography clearly remains the diagnostic gold standard and essential guide to any microneurosurgical or endovascular therapeutic decision concerning cerebral aneurysms. Detailed cerebral angiography is a dynamic study and is influenced by prior axial imaging. It should be tailored to the specific circumstance to obtain information required for selection of the most beneficial treatment
— id: 12564, year: 1996, vol: 6, page: 705, stat: Journal Article,

MR imaging and MR angiography in the diagnosis of dural arteriovenous fistulas
Panasci DJ; Nelson PK
1995 Aug;3(3):493-508, Magnetic resonance imaging clinics of North America
Intracranial DAVFs are most commonly found in the cavernous, transverse, and sigmoid sinuses. MR imaging and MR angiography can be used to screen for these lesions and determine if there is cortical venous drainage. Conventional angiography still has a major role in screening and is mandatory prior to any therapy. Spinal DAVFs are uncommon lesions seen predominantly in older men. The diagnosis can be suspected with MR imaging if a large draining vein is seen in association with swelling and enhancement of the conus and increased signal on T2-weighted images. MR angiography shows some promise in identifying the vascular anatomy of these lesions
— id: 8039, year: 1995, vol: 3, page: 493, stat: Journal Article,

Correlates of arterial-filling patterns in the intracarotid amobarbital procedure
Perrine K; Devinsky O; Luciano DJ; Choi IS; Nelson PK
1995 Jul;52(7):712-716, Archives of neurology
OBJECTIVE: To determine behavioral correlates of anterior cerebral artery (ACA) and posterior cerebral artery (PCA) perfusion patterns in the intracarotid amobarbital sodium procedure. DESIGN: Multivariate analysis of covariance and partial correlations of behavioral measures to ACA crossflow and PCA filling. SETTING: Angiography and the intracarotid amobarbital procedure at a comprehensive epilepsy center. SUBJECTS: Forty-two patients with intractable epilepsy (right-hemisphere seizure focus [n-23]; left-hemisphere seizure focus [n = 19]). MEASUREMENTS: Internal carotid angiography was performed both at a standard injection rate (8 mL of contrast per second) and at 1 mL/s, which matched the rate of the subsequent amobarbital injection. The degree of ipsilateral PCA and contralateral ACA filling were graded on a seven-point scale and compared with postinjection behavior, language, and memory measures. RESULTS: The ACA crossflow did not correlate significantly with that of any measure. The degree of PCA-filling pattern correlated significantly only with the level of consciousness (r = .31, P < .004), but it was not significant after accounting for the effects of seizure laterality, injection side, and amobarbital dosage. Neither ACA crossflow nor PCA filling correlated significantly with memory. The degree of ACA and PCA filling was overestimated at standard angiography (8 mL of contrast medium per second) injection rates. CONCLUSIONS: Although the degree of PCA filling correlates mildly with the level of consciousness postinjection, possibly by perfusion of thalamic or mesencephalic branches, it is not reliably predictive and is less contributory than the injection side and seizure laterality. The PCA filling is not required to produce valid memory assessment in the intracarotid amobarbital procedure, and ACA crossflow is not predictive of behavioral responses
— id: 12754, year: 1995, vol: 52, page: 712, stat: Journal Article,

Wada memory disparities predict seizure laterality and postoperative seizure control
Perrine K; Westerveld M; Sass KJ; Devinsky O; Dogali M; Spencer DD; Luciano DJ; Nelson PK
1995 Sep;36(9):851-856, Epilepsia
We examined the efficacy of a memory difference score (DS: right minus left hemisphere memory) during the Wada test (intracarotid amobarbital procedure, IAP) for predicting seizure laterality and postoperative seizure outcome in 70 left speech dominant patients from two epilepsy centers. DS > or = 2, after addition of 1 point to the left hemisphere injection score to account for aphasia, were noted in 71.4% of patients and correctly predicted surgery side for 98.0% of these patients. The DS related significantly to seizure outcome at 1-year follow-up (p < 0.002) and correctly predicted 80% of patients who were seizure-free. Patients whose DS did not correctly predict seizure laterality more frequently required invasive studies to establish seizure onset. The relationship of the DS to laterality did not differ significantly by class of IAP memory stimuli. When seizures originate from the temporal lobe, the IAP memory DS predicts seizure laterality by assessing the functional adequacy of the involved hemisphere and is predictive of seizure control
— id: 6858, year: 1995, vol: 36, page: 851, stat: Journal Article,

Intraarterial urokinase for acute ischemic stroke during interventional neuroradiological procedures
Berenstein A; Siller KA; Setton A; Nelson PK; Levine DN; Kupersmith M
1994 ;44:A356-A356 Suppl 2, Neurology
— id: 20610, year: 1994, vol: 44, page: A356, stat: Journal Article,

Current status of interventional neuroradiology in the management of meningiomas
Nelson PK; Setton A; Choi IS; Ransohoff J; Berenstein A
1994 Apr;5(2):235-259, Neurosurgery clinics of North America
Most meningiomas are benign and therefore curable lesions. Currently, the best available treatment is complete surgical resection. Toward this end, interventional neuroradiologists should contribute to the efficient and total removal of tumor mass. Although some controversy exists as to the value of the embolization of meningiomas involving the convexity, preoperative embolization certainly is of value in more complex presentations, including giant meningiomas, meningiomas exhibiting malignant or angioblastic characteristics, as well as those involving the skull base, scalp, or critical vascular structures. Several reports have illustrated the importance of preoperative embolization in reducing blood supply to lesions in surgically inaccessible areas. Moreover, several arguments may be advanced in defense of embolization as a method of devascularization superior to dural vessel ligation at the time of operation. Microemboli enter the vascular bed of the tumor and devascularize the lesion irrespective of collateral circulation. In addition, bilateral dural devascularization is easier to accomplish via endovascular techniques and may obviate the need for surgical exposure of the contralateral side during resections of tumors involving the falx or parasagittal region. The tumor necrosis occurring after devascularization by microparticulate emboli may facilitate surgical manipulation. At a theoretical level, embolization may reduce the likelihood of recurrence, particularly from unnoticed invasion of dural venous sinuses or from the surrounding dura. To achieve these goals, embolization should be as complete as possible. This requires a thorough understanding of the disease process and the vascular anatomy involved and superb technique
— id: 12984, year: 1994, vol: 5, page: 235, stat: Journal Article,

Safety of embolic materials
Rosenwasser RH; Berenstein A; Nelson PK; Setton A; Jafar JJ; Marotta T
1993 Jul;79(1):153-155, Journal of neurosurgery
— id: 36683, year: 1993, vol: 79, page: 153, stat: Journal Article,