Aleksandar Beric, M.D.

Major intraoperative neurologic monitoring deficits in consecutive pediatric and adult spinal deformity patients at one institution
Kamerlink, Jonathan R; Errico, Thomas; Xavier, Shaun; Patel, Ashish; Patel, Amar; Cohen, Alexa; Reiger, Mark; Dryer, Joseph; Feldman, David; Lonner, Baron; Beric, Aleksandar; Schwab, Frank
2010 Jan 15;35(2):240-245, Spine
STUDY DESIGN: Retrospective review. OBJECTIVE: The purpose of this study was to assess the preoperative neurologic risk in a consecutive series of spinal deformity patients undergoing correction surgery at one institution. SUMMARY OF BACKGROUND DATA: During spinal deformity correction surgery, neurologic monitoring techniques are commonly applied to reduce the risk of neurologic deficits. While previous studies have demonstrated risk factors for neurologic changes in the setting of spinal surgery, these involved long time spans and heterogeneous patient populations. METHODS: Of 301 cases performed over 1 year, 281 cases were monitorable. Patients were grouped according to diagnosis: neuromuscular (NM) scoliosis, Sagittal Plane deformity, and Scoliosis. Demographic and surgical data were collected for neurologically monitorable patients. Coronal and sagittal parameters were measured using digital images of radiographs. Neurologic status was measured with somatosensory-evoked potentials and/or motor-evoked potentials. RESULTS: Primary NM scoliosis cases had the highest incidence of neurologic monitoring changes (NMC) (10%) while revision sagittal plane deformity had the second highest (9.8%). Sensitivity and specificity were both 100%. Overall incidence of neurologic deficit was 1.1%. Of the 13 NMCs patients, 3 patients had persistent neurologic deficit. Majority of NMCs occurred before deformity correction. In patients with NM scoliosis, NMCs increased with hybrid constructs with wires (P < 0.01). In patients with scoliosis, NMCs increased with increased body mass index, estimated blood loss, operative time, and postoperative coronal thoracolumbar curve magnitude (P < 0.04). In patients with primarily sagittal plane deformity, NMCs increased with preoperative proximal curve, postoperative proximal and thoracolumbar curves, and postoperative kyphosis and lordosis (P < 0.04). CONCLUSION: Primary NM scoliosis and revision sagittal plane deformities appear to carry greatest incidence of NMCs during surgical intervention. Most observed NMCs did not result in a permanent neurologic deficit. Neuromonitoring should be assessed throughout the entire surgical procedure. This study may aid surgeons and patients to better assess neurologic risks related to spinal deformity surgery
— id: 106280, year: 2010, vol: 35, page: 240, stat: Journal Article,

Metabolic correlates of subthalamic nucleus activity in Parkinson's disease
Lin, Tanya P; Carbon, Maren; Tang, Chengke; Mogilner, Alon Y; Sterio, Djordje; Beric, Aleksandar; Dhawan, Vijay; Eidelberg, David
2008 May;131(Pt 5):1373-1380, Brain
Overactivity of subthalamic nucleus (STN) neurons is a consistent feature of Parkinson's disease (PD) and is a target of therapy for this disorder. However, the relationship of STN firing rate to regional brain function is not known. We scanned 17 PD patients with (18)F-fluorodeoxyglucose (FDG) PET to measure resting glucose metabolism before the implantation of STN deep brain stimulation electrodes. Spontaneous STN firing rates were recorded during surgery and correlated with preoperative regional glucose metabolism on a voxel-by-voxel basis. We also examined the relationship between firing rate and the activity of metabolic brain networks associated with the motor and cognitive manifestations of the disease. Mean firing rates were 47.2 +/- 6.1 and 48.7 +/- 8.5 Hz for the left and right hemispheres, respectively. These measures correlated (P < 0.007) with glucose metabolism in the putamen and globus pallidus, which receive projections from this structure. Significant correlations (P < 0.0005) were also evident in the primary motor (BA4) and dorsolateral prefrontal (BA46/10) cortical areas. The activity of both the motor (P < 0.0001) and the cognitive (P < 0.006) PD-related metabolic networks was elevated in these patients. STN firing rates correlated with the activity of the former (P < 0.007) but not the latter network (P = 0.39). The findings suggest that the functional pathways associated with motor disability in PD are linked to the STN firing rate. These pathways are likely to mediate the clinical benefit that is seen following targeted STN interventions for this disease
— id: 93845, year: 2008, vol: 131, page: 1373, stat: Journal Article,

Success rate of motor evoked potentials for intraoperative neurophysiologic monitoring: effects of age, lesion location, and preoperative neurologic deficits
Chen, Xi; Sterio, Djordje; Ming, Xu; Para, Devaki D; Butusova, Marri; Tong, Teresa; Beric, Aleksandar
2007 Jun;24(3):281-285, Journal of clinical neurophysiology
Transcranial electrical stimulation with myogenic motor evoked potential (MEP) recording was used for intraoperative neurophysiologic monitoring in 341 consecutive 'high-risk' neurosurgical or orthopedic procedures. Overall, the success rate for establishing reliable MEP response was 94.8% for upper extremities and 66.6% for lower extremities. The rate was only 39.1% for lower extremities in patients with preoperative motor deficit and up to 81% in neurologically intact adults. Further analysis demonstrated that extremes of age or the presence of a lesion in the spinal cord and motor deficit contributed to failure in obtaining reliable MEPs
— id: 73299, year: 2007, vol: 24, page: 281, stat: Journal Article,

Long-term changes in motor function and stimulation parameters in patients with deep brain stimulation of the subthalamic nucleus for Parkinson's disease
Parker, EC; Beric, A; Sterio, D; Drafta, C; Xu, M; Taverna, PA; Kelly, PJ
2007 JAN-FEB ;85(1):30-31, Stereotactic & functional neurosurgery
— id: 70324, year: 2007, vol: 85, page: 30, stat: Journal Article,

Entrapment neuropathy contributing to dysfunction after brachial plexus birth injuries
Price, Andrew E; Beric, Aleksandar; Yaylali, Ilker; Grossman, John A I
2007 Sep;27(6):717-717, Journal of pediatric orthopedics
— id: 95128, year: 2007, vol: 27, page: 717, stat: Journal Article,

Deep brain stimulation improves orthostatic regulation of patients with Parkinson disease
Stemper, B; Beric, A; Welsch, G; Haendl, T; Sterio, D; Hilz, M J
2006 Nov 28;67(10):1781-1785, Neurology
OBJECTIVE: To evaluate whether subthalamic nucleus (STN) stimulation has an effect on the orthostatic regulation of patients with Parkinson disease (PD), we studied cardiovascular regulation during on and off phases of STN stimulation. METHODS: We examined 14 patients with PD (mean age 58.1 +/- 5.8 years, 4 women, 10 men) with bilateral STN stimulators. Patients underwent 3 minutes of head-up tilt (HUT) testing during STN stimulation and after 90 minutes interruption of stimulation. We monitored arterial blood pressure (BP), RR intervals (RRI), respiration, and skin blood flow (SBF). Baroreflex sensitivity (BRS) was assessed as the square root of the ratio of low-frequency power of RRI to the low-frequency power of systolic BP for coherences above 0.5. RESULTS: During the on phase of the STN stimulation, HUT induced no BP decrease, a significant tachycardia, and a significant decrease of SBF. During the off phase of stimulation, HUT resulted in significant decreases in BPsys and RRI and only a slight SBF decrease. HUT induced no change of BRS during stimulation, but lowered BRS when the stimulator was off (p < 0.05). CONCLUSIONS: STN stimulation of patients with PD increases peripheral vasoconstriction and BRS and stabilizes BP, thereby improving postural hypotension in patients with PD. The results indicate that STN stimulation not only alleviates motor deficits but also influences autonomic regulation in patients with PD
— id: 104800, year: 2006, vol: 67, page: 1781, stat: Journal Article,

A phase I study of oxaliplatin (OX) in combination with bortezomib (B) in patients with advanced malignancy
Chang, R; Beric, A; Liebes, LF; Wright, J; Ivy, P; Norwood, B; Escalon, J; Muggia, FM; Hochster, HS
2005 JUN 1 ;23(16):880S-880S, Journal of clinical oncology
— id: 57806, year: 2005, vol: 23, page: 880S, stat: Journal Article,

Neuropsychological functioning following bilateral subthalamic nucleus stimulation in Parkinson's disease
Morrison, C E; Borod, J C; Perrine, K; Beric, A; Brin, M F; Rezai, A; Kelly, P; Sterio, D; Germano, I; Weisz, D; Olanow, C W
2004 Apr;19(2):165-181, Archives of clinical neuropsychology
The cognitive effects of subthalamic nucleus (STN) stimulation in Parkinson's disease (PD) have been examined. However, there are no reported studies that evaluate, by incorporating a disease control group, whether neuropsychological performance in surgical patients changes beyond the variability of the assessment measures. To examine this issue, 17 PD patients were tested before and after bilateral STN stimulator implantation, both on and off stimulation. Eleven matched PD controls were administered the same repeatable neuropsychological test battery twice. Relative to changes seen in the controls, the surgery for electrode placement mildly adversely affected attention and language functions. STN stimulation, per se, had little effect on cognition. The STN DBS procedure as a whole resulted in a mild decline in delayed verbal recall and language functions. There were no surgery, stimulation, or procedure effects on depression scale scores. In contrast to these group findings, one DBS patient demonstrated significant cognitive decline following surgery
— id: 46217, year: 2004, vol: 19, page: 165, stat: Journal Article,

Location of the active contact within the subthalamic nucleus (STN) in the treatment of idiopathic Parkinson's disease
Zonenshayn, Martin; Sterio, Djordje; Kelly, Patrick J; Rezai, Ali R; Beric, Aleksander
2004 Sep;62(3):216-225, Surgical neurology
BACKGROUND: Chronic electrical stimulation of the subthalamic nucleus (STN) has been shown to be safe and effective in the treatment of medically refractory idiopathic Parkinson's disease. The clinically most relevant location of stimulation within the physiologically defined STN has not been confirmed. We reviewed the locations of active electrical contacts in 33 patients who underwent simultaneous bilateral STN deep brain stimulator (DBS) implantation. METHODS: The location of the microelectrode-defined dorsal STN border was compared to the location of the center of the active contact(s) employed in achieving optimal clinical results 6 to 18 months postoperatively. Furthermore, the location of this optimal contact was determined with respect to each individual patient's midcommissural point. Bilateral monopolar stimulation was employed in 30 patients using quadripolar DBS electrodes. RESULTS: After a minimum follow-up period of 6 months, the motor subscores (UPDRS Part III) in the postoperative on-stimulation/off-medication state were 64 +/- 18% (mean +/- SD) improved as compared to the preoperative off-medication state (p < 0.01). Additionally, an improvement of 53 +/- 38% was noted when comparing the postoperative on-stimulation/on-medication state to the preoperative on-medication state (p < 0.01). On average, the center of the optimal contact was 13.3 mm lateral, 0.5 mm posterior, 0.1 mm inferior to the mid-commissural point and was 0.1 +/- 2.1 mm dorsal to the physiologically defined dorsal STN border. CONCLUSIONS: While the achieved clinical results are comparable to those published in the literature, it appears that monopolar electrical stimulation at the anterior dorsolateral border of the STN yields optimal clinical results. Further studies are crucial in determining the precise mechanism of various modes of DBS in an effort to maximize clinical outcome
— id: 56070, year: 2004, vol: 62, page: 216, stat: Journal Article,

Ulf Lindblom, friend and mentor
Beric, A
2003 JUL ;7(4):301-301, European journal of pain
— id: 37179, year: 2003, vol: 7, page: 301, stat: Journal Article,

Spinal cord injury pain
Beric, Aleksandar
2003 ;7(4):335-338, European journal of pain
Awareness that SCI pain is common emerged during the past decade. However, there are a number of unresolved issues. There is a need for variety of experimental models to reflect diversity of SCI pains. Current classification is not as user-friendly as it should be. More attention should be given to a condition of the spinal cord below and above the SCI lesion. A consensus for what is an optimal SCI functional assessment for patients with sensory complaints and pain should be developed. Further extensive SCI pain research is needed prior to spinal cord regeneration trials in order to be able to cope with a potential for newly developed pains that may appear during incomplete spinal cord regenerative attempts
— id: 42666, year: 2003, vol: 7, page: 335, stat: Journal Article,

Peripheral nerve disorders
Beric, Aleksandar
2002 ;90(3):227-240, Advances in neurology
— id: 39625, year: 2002, vol: 90, page: 227, stat: Journal Article,

Subthalamic nucleus stimulation in patients with a prior pallidotomy
Mogilner, Alon Y; Sterio, Djordje; Rezai, Ali R; Zonenshayn, Martin; Kelly, Patrick J; Beric, Aleksandar
2002 Apr;96(4):660-665, Journal of neurosurgery
OBJECT: A substantial number of patients with Parkinson disease (PD) who have undergone unilateral stereotactic pallidotomy ultimately develop symptom progression, becoming potential candidates for further surgical treatment. Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) has been shown to be effective in the treatment of a subset of patients with refractory PD. Microelectrode recording is performed to help localize the STN and guide final placement of the electrode. Potential alterations in physiological features of the STN after pallidotomy may complicate localization of this structure in this group of patients. METHODS: Bilateral STN DBS surgery guided by microelectrode recording was performed in six patients who had undergone previous unilateral pallidotomies. Physiologically obtained parameters of the STN, including trajectory length, mean firing rate, cell number, and cell density were calculated. These data were compared with those from the side without prior pallidotomy within each patient, as well as with those from our series of 49 subthalamic nuclei explored in 26 patients who had not undergone prior pallidotomy but who underwent bilateral STN stimulator placement. In all patients, analysis of STN cellular activity on the side ipsilateral to the pallidotomy demonstrated a lower mean firing frequency than on the contralateral, intact side. The physiological features on the intact side were not significantly different from those found in our series of patients who had not undergone prior pallidotomy. CONCLUSIONS: Physicians who perform STN surgery in patients with prior pallidotomy should be aware of the electrophysiological differences between the STN that had undergone pallidotomy and the one that had not, to avoid prolonging recording time to search for the typical STN. The implications of these findings for the current models of information processing in the basal ganglia are discussed
— id: 27569, year: 2002, vol: 96, page: 660, stat: Journal Article,

Neurophysiological modulation of the subthalamic nucleus by pallidal stimulation in Parkinson's disease
Sterio, D; Rezai, A; Mogilner, A; Zonenshayn, M; Gracies, J M; Kathirithamby, K; Beric, A
2002 Mar;72(3):325-328, Journal of neurology neurosurgery & psychiatry
OBJECTIVES: Current models of basal ganglia dysfunction in Parkinson's disease suggest a pivotal role of subthalamic nucleus (STN) hyperactivity. There is a direct excitatory output to the globus pallidus internus (GPi), which in turn hyperinhibits the motor thalamus and leads to a lack of cortical facilitation. The model, however, does not address the reciprocal influence of GPi on STN activity. METHODS: Measurement of immediate changes in STN single cell activity after GPi deep brain stimulation (DBS). RESULTS: An opposite effect of GPi DBS in the dorsal versus ventral STN was found. There was an almost exclusive reduction of firing rate in the dorsal region of the STN, whereas the cells in the ventral region exhibited facilitation similar to the recordings from the substantia nigra pars reticulata. CONCLUSION: Although these findings require confirmation, they suggest that the current theories of GPi DBS action, which do not include a GPi-STN modulation, are most likely incomplete
— id: 27276, year: 2002, vol: 72, page: 325, stat: Journal Article,

Neurophysiological refinement of subthalamic nucleus targeting
Sterio, Djordje; Zonenshayn, Martin; Mogilner, Alon Y; Rezai, Ali R; Kiprovski, Kiril; Kelly, Patrick J; Beric, Aleksandar
2002 Jan;50(1):58-67, Neurosurgery
OBJECTIVE: Advances in image-guided stereotactic surgery, microelectrode recording techniques, and stimulation technology have been the driving forces behind a resurgence in the use of functional neurosurgery for the treatment of movement disorders. Despite the dramatic effects of deep brain stimulation (DBS) techniques in ameliorating the symptoms of Parkinson's disease, many critical questions related to the targeting, effects, and mechanisms of action of DBS remain unanswered. In this report, we describe the methods used to localize the subthalamic nucleus (STN) and we present the characteristics of encountered cells. METHODS: Twenty-six patients with idiopathic Parkinson's disease underwent simultaneous, bilateral, microelectrode-refined, DBS electrode implantation into the STN. Direct and indirect magnetic resonance imaging-based anatomic targeting was used. Cellular activity was analyzed for various neurophysiological parameters, including firing rates and interspike intervals. Physiological targeting confirmation was obtained by performing macrostimulation through the final DBS electrode. RESULTS: The average microelectrode recording time for each trajectory was 20 minutes, with a mean of 5.2 trajectories/patient. Typical trajectories passed through the anterior thalamus, zona incerta/fields of Forel, STN, and substantia nigra-pars reticulata. Each structure exhibited a characteristic firing pattern. In particular, recordings from the STN exhibited an increase in background activity and an irregular firing pattern, with a mean rate of 47 Hz. The mean cell density was 5.6 cells/mm, with an average maximal trajectory length of 5.3 mm. Macrostimulation via the DBS electrode yielded mean sensory and motor thresholds of 4.2 and 5.7 V, respectively. CONCLUSION: The principal objectives of microelectrode recording refinement of anatomic targeting are precise identification of the borders of the STN and thus determination of its maximal length. Microelectrode recording also allows identification of the longest and most lateral segment of the STN, which is our preferred target for STN DBS electrode implantation. Macrostimulation via the final DBS electrode is then used primarily to establish the side effect profile for postoperative stimulation. Microelectrode recording is a helpful targeting adjunct that will continue to facilitate our understanding of basal ganglion physiological features
— id: 33634, year: 2002, vol: 50, page: 58, stat: Journal Article,

Complications of deep brain stimulation surgery
Beric A; Kelly PJ; Rezai A; Sterio D; Mogilner A; Zonenshayn M; Kopell B
2001 ;77(1-4):73-78, Stereotactic & functional neurosurgery
Although technological advances have reduced device-related complications, DBS surgery still carries a significant risk of transient and permanent complications. We report our experience in 86 patients and 149 DBS implants. Patients with Parkinson's disease, essential tremor and dystonia were treated. There were 8 perioperative, 8 postoperative, 9 hardware-related complications and 4 stimulation-induced side effects. Only 5 patients (6%) sustained some persistent neurological sequelae, however, 26 of the 86 patients undergoing 149 DBS implants in this series experienced some untoward event with the procedure. Although there were no fatalities or permanent severe disabilities encountered, it is important to extend the informed consent to include all potential complications
— id: 33632, year: 2001, vol: 77, page: 73, stat: Journal Article,

Dexmedetomidine infusion and somatosensory evoked potentials
Bloom M; Beric A; Bekker A
2001 Oct;13(4):320-322, Journal of neurosurgical anesthesiology
Intraoperative neurophysiologic monitoring requires information on the effects of anesthetic drugs because these drugs can directly alter evoked potentials, thus interfering with monitoring. We report on our evaluation of the effect of the recently introduced alpha2-adrenergic agonist, dexmedetomidine, on the somatosensory evoked potentials in two patients undergoing cervico-occipital fusion. Our results suggest that, although dexmedetomidine can affect the later cortical peaks of somatosensory evoked potentials (SSEPs), consistent and reproducible potentials can be recorded
— id: 26547, year: 2001, vol: 13, page: 320, stat: Journal Article,

Comparison of anatomic and neurophysiological methods for subthalamic nucleus targeting [In Process Citation]
Zonenshayn M; Rezai AR; Mogilner AY; Beric A; Sterio D; Kelly PJ
2000 Aug;47(2):282-292, Neurosurgery
OBJECTIVE: The subthalamic nucleus (STN) has recently become the surgical target of choice for the treatment of medically refractory idiopathic Parkinson's disease. A number of anatomic and physiological targeting methods have been used to localize the STN. We retrospectively reviewed the various anatomic targeting methods and compared them with the final physiological target in 15 patients who underwent simultaneous bilateral STN implantation of deep brain stimulators. METHODS: The x, y, and z coordinates of our localizing techniques were analyzed for 30 STN targets. Our final targets, as determined by single-cell microelectrode recording, were compared with the following: 1) targets selected on coronal magnetic resonance inversion recovery and T2-weighted imaging sequences, 2) the center of the STN on a digitized scaled Schaltenbrand-Wahren stereotactic atlas, 3) targeting based on a point 13 mm lateral, 4 mm posterior, and 5 mm inferior to the midcommissural point, and 4) a composite target based on the above methods. RESULTS: All anatomic methods yielded targets that were statistically significantly different (P < 0.001) from the final physiological targets. The average distance error between the final physiological targets and the magnetic resonance imaging-derived targets was 2.6 +/- 1.3 mm (mean +/- standard deviation), 1.7 +/- 1.1 mm for the atlas-based method, 1.5 +/- 0.8 mm for the indirect midcommissural method, and 1.3 +/- 1.1 mm for the composite method. Once the final microelectrode-refined target was determined on the first side, the final target for the contralateral side was 1.3 +/- 1.2 mm away from its mirror image. CONCLUSION: Although all anatomic targeting methods provide accurate STN localization, a combination of the three methods offers the best correlation with the final physiological target. In our experience, direct magnetic resonance targeting was the least accurate method
— id: 11550, year: 2000, vol: 47, page: 282, stat: Journal Article,

Microelectrode recording during posteroventral pallidotomy: impact on target selection and complications
Alterman RL; Sterio D; Beric A; Kelly PJ
1999 Feb;44(2):315-321, Neurosurgery
OBJECTIVE: To assess the practical usefulness of single-cell microelectrode recording (MER) when performing posteroventral pallidotomy. METHODS: A retrospective comparison of the initial, magnetic resonance imaging-derived coordinates of the pallidotomy target to the final, MER-refined lesion coordinates in 132 consecutive pallidotomies was conducted. The time required to perform the procedure and the surgical complications are reported. RESULTS: MER led to targeting changes in 98% of the cases. In 12%, the MER-refined target was more than 4 mm from the original, image-guided site, which is a targeting error that could adversely affect outcome. Although all components of targeting were affected by MER, laterality and depth were impacted most. The ventral border of the globus pallidus pars interna was located within 1 mm of the magnetic resonance imaging-selected target in only 40% of the cases. On average, only 2.2 MER trajectories were required to perform pallidotomy. During the last 3 years of our study, 85% of the procedures were performed with one or two trajectories. The mean operating time of the operations performed during the last 3 years was 2 hours and 12 minutes. The incidence of intracerebral hemorrhage in our series (1.5%) was no higher than that reported for other large series of stereotactic procedures. No patient suffered an optic tract injury. CONCLUSION: MER provides important targeting information for performing pallidotomy. In particular, the micrometric delineation of the ventral border of the globus pallidus pars interna permits safe lesioning of the posteroventral region of the globus pallidus pars interna with little risk of visual field deficit. These data can be obtained efficiently and without increased surgical risk
— id: 25189, year: 1999, vol: 44, page: 315, stat: Journal Article,

Metabolic substrate underlying cognitive dysfunction in Parkinson's Disease
Mentis, M; Edwards, C; Krch, D; Perrine, K; Beric, A; Mattis, P; Nakumura, T; Moeller, JR; Eidelberg, D
1999 MAY ;40(5):267P-268P, Journal of nuclear medicine
— id: 54026, year: 1999, vol: 40, page: 267P, stat: Journal Article,

Central pain and dysesthesia syndrome
Beric A
1998 Nov;16(4):899-918, Neurologic clinics
This article presents recent observations about different recognized central pain syndromes (CPS) and discusses them in light of contemporary microelectrode and imaging findings. Different theories regarding the generation of CPS are reviewed, with an emphasis on difficulties in diagnosis and treatment. The author discourages destructive procedures for treatment of CPS, favoring, instead, reversible procedures such as stimulation techniques and drug delivery systems
— id: 12066, year: 1998, vol: 16, page: 899, stat: Journal Article,

Cognitive functioning after pallidotomy for refractory Parkinson's disease [see comments]
Perrine K; Dogali M; Fazzini E; Sterio D; Kolodny E; Eidelberg D; Devinsky O; Beric A
1998 Aug;65(2):150-154, Journal of neurology neurosurgery & psychiatry
BACKGROUND: Earlier approaches to pallidotomy for refractory Parkinson's disease had significant complication rates. More recent approaches show fewer complications, but the effect of pallidotomy on cognition is unclear. The current study was conducted to examine the neuropsychological effects of unilateral pallidotomy. METHODS: Neuropsychological testing was performed on patients with medically refractory, predominantly unilateral Parkinson's disease at baseline and after unilateral ventral pallidotomy (n=28) or after an equivalent period without surgery in control patients (n=10). RESULTS: Pallidotomy patients showed no significant changes from baseline to retesting relative to the control group for any measure. Across all of the tests administered, only five of the surgery patients showed a significant decline, and of these five none declined on more than one test. Depression did not relate to preoperative or postoperative cognition. The pallidotomy group showed a significant improvement in motor functioning and activities of daily living whereas the control group did not. These measures were not associated with the neuropsychological test scores at baseline or retest. CONCLUSIONS: Stereotactic unilateral ventral pallidotomy does not seem to produce dramatic cognitive declines in most patients
— id: 7740, year: 1998, vol: 65, page: 150, stat: Journal Article,

Pallidal targeting with the COMPASS system
Alterman RL; Kall B; Beric A; Sterio D; Kelly PJ
1997 ;69(1-4 Pt 2):69-72, Stereotactic & functional neurosurgery
The authors describe their initial experience with the new pallidotomy targeting software for the COMPASS system. As COMPASS permits window and contrast settings to be changed at any time, multiple imaging modalities can be employed for targeting. This feature allowed the incorporation of fast-spin echo/inversion recovery (FSE/IR) magnetic resonance images (MRI) into the planning protocol. COMPASS has now been employed for 33 consecutive pallidotomies over the last year (July 96-June 97). A statistically significant reduction in the number of microelectrode recording trajectories required to physiologically localize sensorimotor globus pallidus interna (GPi) is noted in these cases as compared to the 41 cases performed in the previous year with a different computer planning system. The authors conclude that the COMPASS system accurately and efficiently targets the internal pallidum when FSE/IR MRI is employed. Nevertheless, pallidotomy should not be performed without neurophysiological localization
— id: 7296, year: 1997, vol: 69, page: 69, stat: Journal Article,

Selection criteria for unilateral posteroventral pallidotomy
Alterman RL; Kelly P; Sterio D; Fazzini E; Eidelberg D; Perrine K; Beric A
1997 ;68(5):18-23, Acta neurochirurgica. Supplementum
In an attempt to refine the indications for posteroventral pallidotomy (PVP) the authors instituted strict selection criteria which are based on the experience gained from the first 60 pallidotomy patients treated at their institution. In addition to clinical evaluation, all pallidotomy candidates undergo neuropsychological testing and 18F-fluoro-deoxyglucose utilization positron emission tomography (FDG/PET). The data from which these criteria were developed are presented as are early clinical results. The authors demonstrate that these criteria enhance the efficacy of the procedure by assuring therapeutic response and reducing the incidence of post-operative dementia. Their indications and contraindications for pallidotomy are discussed
— id: 25191, year: 1997, vol: 68, page: 18, stat: Journal Article,

Left-right differences in motor thresholds after stimulation of the globus pallidus before pallidotomy
Beric A; Sterio D; Dogali M; Kelly P
1997 Aug;63(2):159-162, Journal of neurology neurosurgery & psychiatry
Left-right upper limb motor threshold differences were found after electrical stimulation of the globus pallidus administered as a neuroprotective measure to avoid lesioning of the internal capsule during stereotactic pallidotomy for treatment of Parkinson's disease. Left sided stimulation resulted in lower thresholds in right handed patients compared with left handed patients. These differences were significant in women, but no significant differences were found in men. In patients undergoing bilateral pallidotomy, the stimulation produced more significant left-right motor threshold differences. In the absence of known sex-related anatomical left-right corticospinal tract differences, the variability was the result of spinal excitability modulations most likely related to handedness
— id: 7113, year: 1997, vol: 63, page: 159, stat: Journal Article,

Metabolic correlates of pallidal neuronal activity in Parkinson's disease
Eidelberg D; Moeller JR; Kazumata K; Antonini A; Sterio D; Dhawan V; Spetsieris P; Alterman R; Kelly PJ; Dogali M; Fazzini E; Beric A
1997 Aug;120 ( Pt 8)(2):1315-1324, Brain
We have used [18F]fluorodeoxyglucose and PET to identify specific metabolic covariance patterns associated with Parkinson's disease and related disorders previously. Nonetheless, the physiological correlates of these abnormal patterns are unknown. In this study we used PET to measure resting state glucose metabolism in 42 awake unmedicated Parkinson's disease patients prior to unilateral stereotaxic pallidotomy for relief of symptoms. Spontaneous single unit activity of the internal segment of the globus pallidus (GPi) was recorded intraoperatively in the same patients under identical conditions. The first 24 patients (Group A) were scanned on an intermediate resolution tomograph (full width at half maximum, 8 mm); the subsequent 18 patients (Group B) were scanned on a higher resolution tomograph (full width half maximum, 4.2 mm). We found significant positive correlations between GPi firing rates and thalamic glucose metabolism in both patient groups (Group A: r = 0.41, P < 0.05; Group B: r = 0.69, P < 0.005). In Group B, pixel-based analysis disclosed a significant focus of physiological-metabolic correlation involving the ventral thalamus and the GPi (statistical parametric map: P < 0.05, corrected). Regional covariance analysis demonstrated that internal pallidal neuronal activity correlated significantly (r = 0.65, P < 0.005) with the expression of a unique network characterized by covarying pallidothalamic and brainstem metabolic activity. Our findings suggest that the variability in pallidal neuronal firing rates in Parkinson's disease patients is associated with individual differences in the metabolic activity of efferent projection systems
— id: 18381, year: 1997, vol: 120 ( Pt 8), page: 1315, stat: Journal Article,

Stereotactic pallidotomy for Parkinson's disease: a long-term follow-up of unilateral pallidotomy
Fazzini E; Dogali M; Sterio D; Eidelberg D; Beric A
1997 May;48(5):1273-1277, Neurology
Eleven patients suffering from Parkinson's disease were followed for up to 4 years after unilateral pallidotomy. We observed persistent contralateral improvement and unexpected ipsilateral improvement of motor symptoms. In addition, there was a protracted relief of contralateral dyskinesias and maintenance of relatively stable levodopa dosage
— id: 7143, year: 1997, vol: 48, page: 1273, stat: Journal Article,

Preoperative indicators of clinical outcome following stereotaxic pallidotomy
Kazumata K; Antonini A; Dhawan V; Moeller JR; Alterman RL; Kelly P; Sterio D; Fazzini E; Beric A; Eidelberg D
1997 Oct;49(4):1083-1090, Neurology
We assessed the utility of preoperative clinical assessment and functional brain imaging with 18F-fluorodeoxyglucose (FDG) and positron emission tomography (PET) in predicting the clinical outcome of stereotaxic pallidotomy for the treatment of advanced Parkinson's disease (PD). Twenty-two PD patients undergoing posteroventral pallidotomy were assessed preoperatively with the Core Assessment Program for Intracerebral Transplantation (CAPIT) ratings measured on and off levodopa; quantitative FDG/PET was also performed before surgery. Preoperative clinical and metabolic measurements were correlated with changes in off-state CAPIT ratings determined 3 months after surgery. Clinical outcome following pallidotomy was also correlated with intraoperative measures of spontaneous pallidal single-unit activity as well as postoperative MRI measurements of lesion volume and location. We found that unilateral pallidotomy resulted in variable clinical improvement in off-state CAPIT scores for the contralateral limbs (mean change 30.9 +/- 15.5%). Postoperative MRI revealed that pallidotomy lesions were comparable in location and volume across the patients. Clinical outcome following surgery correlated significantly with preoperative measures of CAPIT score change with levodopa administration (r = 0.60, p < 0.005) and with preoperative FDG/PET measurements of lentiform glucose metabolism (r = 0.71, p < 0.0005). Operative outcome did not correlate with intraoperative measures of spontaneous pallidal neuronal firing rate. We conclude that preoperative measurements of lentiform glucose metabolism and levodopa responsiveness may be useful indicators of motor improvement following pallidotomy. Both preoperative quantitative measures, either singly or in combination, may be helpful in selecting optimal candidates for surgery
— id: 25190, year: 1997, vol: 49, page: 1083, stat: Journal Article,

Electrical stimulation of the globus pallidus preceding stereotactic posteroventral pallidotomy
Beric A; Sterio D; Dogali M; Alterman R; Kelly P
1996 ;66(4):161-169, Stereotactic & functional neurosurgery
Physiological methods such as microelectrode recording of neuronal activity and electrical stimulation of target structures can improve the safety and efficacy of certain stereotactic surgeries. The globus pallidus (GP) was electrically stimulated in 136 patients with Parkinson's disease prior to unilateral posteroventral pallidotomy to identify functional areas and prevent deficits. We found that electrical stimulation of the GP elicited two principal responses: contractions of the contralateral hand and flashing lights. The mean voltage that evoked motor responses was 4.3 V (range 1.7-9.0 V), while higher intensity was necessary to elicit visual responses (mean 6.8 V; range 3.5-9.9 V). Contralateral tremor, speech impairment, paresthesias, and warm sensations were also elicited
— id: 7112, year: 1996, vol: 66, page: 161, stat: Journal Article,

Characteristics of pallidal neuronal discharges in Parkinson's disease patients
Beric A; Sterio D; Dogali M; Fazzini E; Eidelberg D; Kolodny E
1996 ;69:123-128, Advances in neurology
— id: 12696, year: 1996, vol: 69, page: 123, stat: Journal Article,

Effects of posteroventral pallidotomy on Parkinson's disease
Dogali M; Sterio D; Fazzini E; Kolodny E; Eidelberg D; Beric A
1996 ;69(4):585-590, Advances in neurology
— id: 18386, year: 1996, vol: 69, page: 585, stat: Journal Article,

Regional metabolic correlates of surgical outcome following unilateral pallidotomy for Parkinson's disease
Eidelberg D; Moeller JR; Ishikawa T; Dhawan V; Spetsieris P; Silbersweig D; Stern E; Woods RP; Fazzini E; Dogali M; Beric A
1996 Apr;39(4):450-459, Annals of neurology
Stereotaxic ventral pallidotomy has been employed in the symptomatic treatment of patients with advanced Parkinson's disease (PD). To understand the pathophysiology of clinical outcome following this procedure, we studied 10 PD patients (5 men and 5 women; mean age 60.0 +/- 6.1 years; mean Hoehn and Yahr stage 3.8 +/- 1.0) with quantitative 18F-fluorodeoxyglucose (FDG) and positron emission tomography (PET). All patients were scanned preoperatively; 8 of 10 patients were rescanned 6 to 8 months following surgery. Clinical performance was assessed off medications before and after surgery using standardized timed motor tasks. We found that preoperative lentiform metabolism correlated significantly with improvement in contralateral motor tasks at 1 week, 3 months, and 6 months following unilateral pallidotomy (p<0.03). Postoperatively, significant metabolic increases were noted in the primary motor cortex, lateral premotor cortex, and dorsolateral prefrontal cortex (p<0.01) of the hemisphere that underwent surgery. Improvement in contralateral limb motor performance correlated significantly with surgical declines in thalamic metabolism (p<0.01) and increases in lateral frontal metabolism (p<0.05). Principal components analysis disclosed a significant covariance pattern characterized by postoperative declines in ipsilateral lentiform and thalamic metabolism associated with bilateral increase in supplementary motor control metabolism. Subject scores for this pattern correlated significantly with improvements in both contralateral and ipsilateral limb performance (p<0.005). These results suggest that pallidotomy reduced the preoperative overaction of the inhibitory pallidothalamic projection. Clinical improvement may be associated with modulations in regional brain metabolism occurring remote from the lesion site
— id: 18385, year: 1996, vol: 39, page: 450, stat: Journal Article,

The relative sensitivity of F wave and H reflex to changes in motoneuronal excitability
Leis, AA; Stetkarova, I; Beric, A; Stokic, DS
1996 OCT ;19(10):1342-1344, Muscle & nerve
— id: 52810, year: 1996, vol: 19, page: 1342, stat: Journal Article,

Surgical maneuvers placing the sciatic nerve at risk during total hip arthroplasty as assessed by somatosensory evoked potential monitoring
Pereles, T R; Stuchin, S A; Kastenbaum, D M; Beric, A; Lacagnino, G; Kabir, H
1996 Jun;11(4):438-444, Journal of arthroplasty
The sciatic nerve in 52 hip arthroplasties was evaluated using intraoperative somatosensory evoked potentials (SSEPs). Twenty-nine of these cases involved the lateral transtrochanteric approach, and 23 involved the posterior approach. A total of 11 incidents of SSEP changes occurred in eight patients. Six episodes occurred during lateral retraction of the proximal femur, and three occurred during anterior retraction of the proximal femur. Tracings returned to baseline with prompt cessation of femoral retraction in each case. One SSEP change occurred in a revision following reduction of the prosthetic components, and this resolved with shortening of the prosthetic neck to less than anatomic length. One change occurred during tightening of cables securing strut allografts to the femur and this resolved spontaneously. No correlation was found between frequency of SSEP changes and age, sex, limb lengthening, or preoperative range of motion. It is concluded that routine lateral or anterior retraction may place the sciatic nerve at risk
— id: 131563, year: 1996, vol: 11, page: 438, stat: Journal Article,

Anatomic and physiological considerations in pallidotomy for Parkinson's disease
Dogali M; Beric A; Sterio D; Eidelberg D; Fazzini E; Takikawa S; Samelson DR; Devinsky O; Kolodny EH
1995 ;64:9-12, Acta neurochirurgica. Supplementum
Our ongoing study of ventral pallidotomy for the control of Parkinson's disease in selected patients has provided the opportunity to explore the topographical and somatotopic organization of the human globus pallidus. Utilizing microelectrode techniques we have obtained recordings which were correlated with data from MPTP-parkinsonian primates. In addition, we performed pre- and post-operative FDG/PET scans in these patients. Our studies reveal similarities between the MPTP-parkinsonian primate model and human Parkinson's disease in terms of physiologic recordings and responses. However, we have encountered significant differences between dominant and non-dominant hemisphere representations, particularly for the hand, in the human. In addition, our PET studies confirmed, as in previous parkinsonian primate models, glucose hypermetabolism in the lenticular area of Parkinson's disease patients. This hypermetabolism is dramatically altered by creation of a lesion in the globus pallidus medialis. This is demonstrated by follow-up PET scans which reveal not only a decrease in metabolism of the operated lenticular region, but also in the frontal cortical projections. These combined observations of the cellular activity in the globus pallidus and the observed changes in PET metabolism support the selection of the pallidum for lesioning and control of Parkinson's disease, and offer insight into the underlying physiology of this disorder. The above physiological and PET data will be clinically correlated with our ongoing series of 35+ patients
— id: 12822, year: 1995, vol: 64, page: 9, stat: Journal Article,

Stereotactic ventral pallidotomy for Parkinson's disease
Dogali M; Fazzini E; Kolodny E; Eidelberg D; Sterio D; Devinsky O; Beric A
1995 Apr;45(4):753-761, Neurology
Eighteen patients with medically intractable Parkinson's disease that was characterized by bradykinesia, rigidity, and marked 'on-off' fluctuations underwent stereotactic ventral pallidotomy under local anesthesia. Targeting was aided by anatomic coordinates derived from the MRI, intraoperative cell recordings, and electrical stimulation prior to lesioning. A nonsurgically treated group of seven similarly affected individuals was also followed. Assessment of motor function was made at baseline and at 3-month intervals for 1 year. Following the lesioning, patients improved in bradykinesia, rigidity, resting tremor, and balance with resolution of medication-induced contralateral dyskinesia. When compared with preoperative baseline, all quantifiable test scores after surgery improved significantly with the patients off medications for 12 hours: UPDRS by 65%, and CAPIT subtest scores on the contralateral limb by 38.2% and the ipsilateral limb by 24.2%. Walk scores improved by 45%. Medication requirements were unchanged, but the patients who had had surgery were able to tolerate larger doses because of reduced dyskinesia. Ventral pallidotomy produces statistically significant reduction in parkinsonism and contralateral 'on' dyskinesia without morbidity or mortality and with a short hospitalization in Parkinson's disease patients for whom medical therapy has failed
— id: 12789, year: 1995, vol: 45, page: 753, stat: Journal Article,

The Effects of unilateral ventral posterior medial pallidotomy in patients with
Fazzini E; Dogali M; Beric A; Eidelberg D; Sterio D; Gianutsos J; Newman B; Kluger A
Therapy of Parkinson's disease New York: Dekker, 1995,
— id: 2605, year: 1995, vol: , page: 353, stat: Chapter,

Thermal perception thresholds: influence of determination paradigm and reference temperature
Hilz MJ; Glorius S; Beric A
1995 Apr;129(2):135-140, Journal of the neurological sciences
The use of different paradigms and initial skin and thermode reference temperatures in quantitative thermal testing does not allow strict comparison of results generated from different laboratories. We tested (a) whether the reproducibility of the method of limits is higher for measurement of isolated warm and cold thresholds (WT, CT) as compared to difference limen (DL) thresholds, i.e. values derived from alternating warm and cold stimulation, and (b) whether WT-, CT- and DL-thresholds depend on the value of baseline skin and thermode temperatures. In 20 healthy volunteers WT-, CT-, and DL-thresholds were determined at the volar wrist using a Somedic-Thermotest. In condition A the baseline thermode temperature was set at 30 degrees C, and in conditions B and C at 35 degrees C; in condition C the tested skin area was also warmed to 35 degrees C prior to the test. The randomized tests were repeated within 1-8 days. WT-, CT-, and DL-values were reproducible, but DL-values were more widely spread than WT and CT. CT variability was lowest in condition A, and WT variability in condition C. We conclude that DL determination should be abandoned, since CT and WT better differentiate normal from abnormal thresholds than the coarse DL-values. We recommend the use of the lower baseline thermode temperature (30 degrees C) and elimination of warming of the tested skin area prior to the test
— id: 6642, year: 1995, vol: 129, page: 135, stat: Journal Article,

SPINAL MOTOR-NEURON EXCITABILITY DURING THE CUTANEOUS SILENT PERIOD
LEIS, AA; STETKAROVA, I; BERIC, A; STOKIC, DS
1995 DEC ;18(12):1464-1470, Muscle & nerve
The physiologic mechanisms generating the cutaneous silent period (CSP) remain uncertain. It is not known whether the CSP occurs because of inexcitability of the spinal motor neuron, We, therefore, assessed excitability of the motor neuron during the CSP using F-wave responses, H-reflexes were also elicited during the CSP, Electrical stimulation to the fifth digit produced the CSP in the voluntarily contracting abductor pollicis brevis muscle (APE), Median nerve stimulation al the wrist elicited control F or H responses during isometric APB contraction (condition 1) and in resting muscle (condition 2), Control amplitudes were compared to those elicited in the midst of the CSP. In Condition 1, F-wave amplitudes and frequency during the CSP were unchanged compared with controls, However, F-waves were increased in amplitude and frequency during the CSP (P < 0.001) relative to responses elicited in resting muscle (condition 2), H-reflexes during the CSP were suppressed (P < 0.001) compared with controls elicited during contraction (condition 1), but facilitated relative to the resting state (condition 2) in which no H-reflexes were elicitable. We conclude that spinal motor neurons remain excitable to antidromic volleys at the same time that the corticospinal volley is inhibited to produce the CSP, Moreover, motor neuron excitability appears to be increased during the CSP compared to the relaxed state. (C) 1995 John Wiley & Sons, Inc
— id: 52668, year: 1995, vol: 18, page: 1464, stat: Journal Article,

Peripheral nerve disorders in pregnancy
Beric A
1994 ;64:179-192, Advances in neurology
— id: 13011, year: 1994, vol: 64, page: 179, stat: Journal Article,

Anatomic and physiological considerations in pallidotomy for Parkinson's disease
Dogali M; Beric A; Sterio D; Eidelberg D; Fazzini E; Takikawa S; Samelson DR; Devinsky O; Kolodny EH
1994 ;62(1-4):53-60, Stereotactic & functional neurosurgery
Our ongoing study of central pallidotomy for the control of Parkison's disease in selected patients has provided the opportunity to explore the topographical and somatotopic organization of the human globus pallidus. Utilizing microelectrode techniques we have obtained recordings which were correlated with data from MPTP-parkinsonian primates. In addition, we performed pre- and postoperative FDG/PET scans in these patients. Our studies reveal similarities between the MPTP-parkisonian primate model and human Parkinson's disease in terms of physiological recordings and responses. However, we have encountered significant differences between dominant and nondominant hemisphere representations, particularly for the hand, in the human. In addition, our PET studies confirmed, as in previous parkinsonian primate models, glucose hypermetabolism in the lenticular area of Parkinson's disease patients. This hypermetabolism is dramatically altered by creation of a lesion in the globus pallidus medialis. This is demonstrated by follow-up PET scans which reveal not only a decrease in metabolism of the operated lenticular region, but also in the frontal cortical projections. These combined observations of the cellular activity in globus pallidus and the observed changes in PET metabolism support the selection of the pallidum for lesioning and control of Parkinson's disease, and offer insight into the underlying physiology of this disorder. The above physiological and PET data will be clinically correlated with our ongoing series of 35+ patients
— id: 13043, year: 1994, vol: 62, page: 53, stat: Journal Article,

Is heat hypoalgesia a useful parameter in quantitative thermal testing of alcoholic polyneuropathy?
Hilz MJ; Claus D; Neundorfer B; Zimmermann P; Beric A
1994 Dec;17(12):1456-1460, Muscle & nerve
Detection of thermal hypoaesthesia, hyperalgesia, and paradoxical sensation significantly contribute to the diagnosis of polyneuropathy (PNP). There is controversy about the clinical usefulness of detected heat hypoalgesia. In 50 chronic alcoholic patients we compared the prevalence and diagnostic value of heat hypoalgesia (HPT) to that of cold (CT) and warm (WT) hypoaesthesia using a 'Marstock' thermotest. Clinical examination revealed PNP in 56%, cold hypoaesthesia was present in 62%, warm hypoaesthesia in 24%, paradoxical thermal sensation in 10%, cold and heat hyperalgesia in 12%, and heat hypoalgesia in 22%. Only 1 patient (2%) presented with heat hypoalgesia but normal warm and cold thresholds; he reported paradoxical thermal sensation and had PNP. One patient suffered first degree burn injury from heat pain examination. Heat hypoalgesia contributed least to the diagnosis of polyneuropathy (HPT versus CT: P < 0.001). In patients with sensory loss, testing heat hypoalgesia bears some risk of burn injury. In contrast to thermal hypoaesthesia and hyperalgesia, it does not significantly enrich the diagnostic workup of alcoholic polyneuropathies
— id: 12858, year: 1994, vol: 17, page: 1456, stat: Journal Article,

Neurophysiological properties of pallidal neurons in Parkinson's disease
Sterio D; Beric A; Dogali M; Fazzini E; Alfaro G; Devinsky O
1994 May;35(5):586-591, Annals of neurology
Neuronal properties of the human globus pallidus (GP) are not known. Since GP is the major output of the basal ganglia, it may be involved in the pathophysiology of Parkinson's disease. We studied 12 patients with medically resistant Parkinson's disease by using single cell recording of the GP during stereotaxic pallidotomy to define neuronal firing rate and its modulation during active and passive movements. Different frequency and pattern of single cell activity was found in globus pallidus externus compared with globus pallidus internus. Discharge rates of 19% of GP cells were modulated by passive contralateral movements. Pallidal units were most often related solely to single joint movement. Different patterns of activity in relation to the two different movements of the same joint were often observed. We identified somatotopically arranged cell clusters that alter discharge rate with related movements. These findings suggest at least a partial somatotopic organization of the human GP and similarity with experimental results in both healthy and MPTP monkeys, providing a rationale for surgical or pharmacological targeting of GP for treating Parkinson's disease
— id: 12968, year: 1994, vol: 35, page: 586, stat: Journal Article,

DYSAESTHESIAE INDUCED BY PHYSIOLOGICAL AND ELECTRICAL ACTIVATION OF POSTERIOR COLUMN AFFERENTS AFTER STROKE
TRIGGS, WJ; BERIC, A
1994 SEP ;57(9):1077-1080, Journal of neurology neurosurgery & psychiatry
Six of 48 stroke patients had functionally limiting dysaesthesiae induced by repetitive light touch, joint movement, or neuromuscular electrical stimulation (NMS). Only one of these six patients had a thalamic lesion. Quantitative sensory testing showed substantial impairment of pain and temperature sensation in all six patients, whereas light touch, vibration and position sense, and graphaesthesia were normal (three patients) or relatively spared (three patients). By contrast, none of 15 stroke patients in whom NMS did not evoke dysaesthesiae had clinical evidence of dissociated sensory loss. Conscious perception of joint movement and light touch is mediated mainly by the population of large myelinated activated preferentially by low intensity electrical stimulation. It is suggested that activation of these nonnociceptive, presumably dorsal column, afferents may contribute to dysaesthesiae in some patients with sensory loss after stroke
— id: 98435, year: 1994, vol: 57, page: 1077, stat: Journal Article,

Central pain: "new" syndromes and their evaluation
Beric A
1993 Oct;16(10):1017-1024, Muscle & nerve
Central pain syndrome is defined as pain associated with a lesion of the central nervous system. It has a low incidence but is frequently intractable and does not have effective treatment. The cause of central pain is speculative; however, the single common sensory abnormality in patients with central pain is interruption of spinothalamocortical nociceptive pathways. It appears that severe central nervous system lesions, with total destruction of ascending sensory systems, do not lead to a central pain syndrome; and that setting of mild, moderate, or severe disruption of the anterolateral ascending system with partial or complete preservation of the dorsal column/medial lemniscus functions is most frequently associated with central pain syndrome. Furthermore, even during remission, dysesthesias and pain could be triggered by additional afferent input to the large fiber/dorsal column/medial lemniscus system and, once established, they may not be abolished by additional deafferentation
— id: 13062, year: 1993, vol: 16, page: 1017, stat: Journal Article,

Transcranial electrical and magnetic stimulation
Beric A
1993 ;63:29-42, Advances in neurology
— id: 13328, year: 1993, vol: 63, page: 29, stat: Journal Article,

ANORGASMIA IN ANTERIOR SPINAL-CORD SYNDROME
BERIC, A; LIGHT, JK
1993 MAY ;56(5):548-551, Journal of neurology neurosurgery & psychiatry
Three male and two female patients with anorgasmia and dissociated sensory loss due to an anterior spinal cord syndrome are described. Clinical, neurophysiological and quantitative sensory evaluation revealed preservation of the large fibre dorsal column functions from the lumbosacral segments with concomitant severe dysfunction or absence of the small fibre neospinothalamic mediated functions. These findings indicate a role for the spinothalamic system in orgasm
— id: 54132, year: 1993, vol: 56, page: 548, stat: Journal Article,

Electrical and magnetic stimulation of the brain and spinal cord
Devinsky, Orrin; Beric, Aleksandar; Dogali, Michael
New York, N.Y : Raven Press, c1993,
— id: 468, year: 1993, vol: , page: , stat: ,

Multiple subpial cortical transections for the control of intractable epilepsy in exquisite cortex
Dogali M; Devinsky O; Luciano D; Perrine K; Beric A
1993 ;58:198-200, Acta neurochirurgica. Supplementum
In 5 cases suffering from intractable seizures and ictal onset in exquisite (primary somatosensory or language related) cortex, surgical therapy has been done consisting wholly or in part of multiple subpial transections. In two cases with involvement of the primary somatosensory cortex, good seizure control without detectable neurological deficit was achieved. In the other three cases with involvement of the language cortex, deficits were minimal and cleared with time. Patients became seizure-free
— id: 56520, year: 1993, vol: 58, page: 198, stat: Journal Article,

SYSTEMIC LIDOCAINE THERAPY FOR POSTSTROKE PAIN
EDMONDSON, EA; SIMPSON, RK; STUBLER, DK; BERIC, A
1993 OCT ;86(10):1093-1096, Southern medical journal
Poststroke pain syndrome is commonly regarded as an intractable disease. We describe four patients who responded to an intravenous lidocaine infusion for relief of central pain after a stroke. The infusion was administered over a 48-hour period after an initial bolus of 50 to 100 mg intravenously over 40 to 120 seconds. Pain intensity and pain relief were measured by visual analog and numeric scales. All patients reported some relief within the first 12 hours of infusion. All patients were subsequently given a trial of mexiletine, an oral congener of lidocaine. Two have continued taking the drug and report excellent relief at 12 months' follow-up; the other two had side effects that precluded further use of the drug. We conclude that lidocaine can reduce poststroke pain, and we propose a treatment algorithm based on our experience with 40 additional patients treated for other neuropathic pain states
— id: 98459, year: 1993, vol: 86, page: 1093, stat: Journal Article,

DETRUSOR FUNCTION WITH LESIONS OF THE CAUDA-EQUINA, WITH SPECIAL EMPHASIS ON THE BLADDER NECK
LIGHT, JK; BERIC, A; PETRONIC, I
1993 MAR ;149(3):539-542, Journal of urology
A total of 13 patients with proved lesions of the cauda equina underwent neurourological evaluation. All patients had video urodynamic testing, while 9 underwent a varying combination of pelvic floor electromyography, lumbosacral evoked potentials to tibial nerve stimulation and the sympathetic skin response from the perineum. All patients had detrusor areflexia with varying degrees of bladder neck incompetence. Reports of clinical and experimental studies are discussed in relation to the pathophysiology of bladder neck function following lesions of the pudendal and preganglionic pelvic nerve to explain why there have been conflicting reports in the literature regarding bladder neck function with lesions of the cauda equina. The adaptive changes observed in the experimental animal, consisting of random regeneration of the cholinergic neuroeffective junctions, adrenergic hyperinnervation and an increased sensitivity of the prejunctional inhibitory muscarinic receptors on the adrenergic nerve, may explain the degree of variability of bladder neck incompetence observed clinically
— id: 98467, year: 1993, vol: 149, page: 539, stat: Journal Article,

GIANT SOMATOSENSORY EVOKED-POTENTIALS IN A PATIENT WITH THE ANTERIOR SPINAL ARTERY SYNDROME
TRIGGS, WJ; BERIC, A
1993 MAY ;16(5):492-497, Muscle & nerve
We studied a previously healthy 25-year-old woman with the anterior spinal artery syndrome, a rare thoracocervical myelopathy with multiple potential etiologies. Quantitative and clinical sensory examination showed dissociated loss of pin-prick and temperature discrimination below the level of the lesion, with normal light touch, vibratory, and position sense. Magnetic resonance imaging was consistent with cervical spinal cord infarction. Median SEPs showed normal Erb's potential with absent spinal N13BAR and normal scalp N20BAR latency. Tibial SEPs showed normal lumbosacral responses and normal scalp P30BAR latency. Both median and tibial nerve stimulation produced cortical responses of unusually large amplitude (median 38 muV, tibial 17 muV). We hypothesize that large SEP amplitudes in this patient resulted from loss of anterolateral inhibitory influences on the dorsal column-medial lemniscal system
— id: 54187, year: 1993, vol: 16, page: 492, stat: Journal Article,

FUNCTION OF THE CONUS MEDULLARIS AND CAUDA-EQUINA IN THE EARLY PERIOD FOLLOWING SPINAL-CORD INJURY AND THE RELATIONSHIP TO RECOVERY OF DETRUSOR FUNCTION
BERIC, A; LIGHT, JK
1992 DEC ;148(6):1845-1848, Journal of urology
A total of 26 patients with an early suprasacral spinal cord injury underwent comprehensive neurourological evaluation to determine if there was any correlation between the return of detrusor function and neural function of the sacral cord. In addition, the incidence of a subclinical sacral neural dysfunction early after spinal cord injury was assessed. Lumbosacral evoked potentials to tibial nerve stimulation were used to assess the sensory root and cord gray matter of the L5 to S2 segments, while urodynamic evaluation was performed to assess detrusor function. Of those patients with normal lumbosacral evoked potentials 82% recovered detrusor contractility as opposed to 66% with abnormal evoked potentials. Four patients (23.5%) had persistent detrusor areflexia when studied 9 to 20 months following the acute injury. The potential problems attempting to correlate the neurophysiological and urodynamic studies are multiple and are extensively discussed. Despite these potential problems the return of detrusor function correlated well with associated normal lumbosacral evoked potentials suggesting that this test can be used in the early phase following spinal cord injury to predict return of bladder function, since it is independent of the level of spinal cord excitability. Of the patients studied 38% had coexistence of an occult lumbosacral dysfunction. This rate is higher than that found in the chronic stabilized spinal cord injury population (20.5%), since the cases in our study may represent a more severe lesion
— id: 51811, year: 1992, vol: 148, page: 1845, stat: Journal Article,

Facilitation of motor evoked potentials by somatosensory afferent stimulation
Deletis V; Schild JH; Beric A; Dimitrijevic MR
1992 Oct;85(5):302-310, Electroencephalography & clinical neurophysiology
The effect of an electrically induced peripheral afferent volley upon electrical and magnetic motor evoked potentials (MEPs) from muscles of the upper and lower extremities was studied in 16 healthy volunteers. A standard conditioning-test (C-T) paradigm was employed whereby the test stimulus (transcranial electric or magnetic) was applied at random time intervals, from 10 msec prior to 90 msec after the conditioning stimulus (peripheral nerve stimulus). MEP amplitude facilitation was observed for the majority of the upper extremity muscles tested at two distinct periods, one occurring at short, and the other at long C-T intervals. This bimodal trend of MEP facilitation was found to be equally as prominent in the lower extremity muscles tested. The period of short C-T interval facilitation is consistent with modifications in the spinal excitability of the segmental motoneuron pool. On the other hand, the period of long C-T interval facilitation is suggested to be due to alterations in excitability of the motor cortex as a result of the arrival of the orthodromic sensory volley. Although most pronounced in muscles innervated by the nerve to which the conditioning stimulus was applied, this bimodal facilitatory effect was also observed in adjacent muscles not innervated by the stimulated nerve. Qualitatively, the conditioned MEPs from the upper and lower extremities responded similarly to both electrical and magnetic trans-cranial stimulation. In addition, our study demonstrates that the C-T paradigm has potential for use in the assessment of spinal and cortical sensorimotor integration by providing quantitative information which cannot be obtained through isolated assessment of sensory and/or motor pathways.(ABSTRACT TRUNCATED AT 250 WORDS)
— id: 13423, year: 1992, vol: 85, page: 302, stat: Journal Article,

Electrically evoked long loop responses (LLR): normative data for upper and lower extremities
Deletis V; Beric A
1989 Nov-Dec;29(7-8):433-437, Electromyography & clinical neurophysiology
Long loop responses can be obtained repeatedly in all neurologically healthy subjects with low variability of onset and peak latencies. Long loop responses showed characteristic features separate from microreflexes of Bickford. Normative data will help us to elucidate the characteristic alterations of these reflexes in different pathologies which involve somatosensory pyramidal and extrapyramidal systems
— id: 45723, year: 1989, vol: 29, page: 433, stat: Journal Article,

Peripheral afferents of H-reflex and long latency responses
Deletis V; Beric A; Dimitrijevic MR
1989 ;:8-8, Abstracts (American Academy of Clinical Neurophysiology)
— id: 55899, year: 1989, vol: , page: 8, stat: Journal Article,

Studija somatosenzoricnih evociranih potencijala na stimulaciju donjih ekstremiteta kod coveka
Beric, Aleksandar
Ljubljana : [s.n.], 1981,
Disertacija - Univ. Ljubljana, Medicinska fak
— id: 2103, year: 1981, vol: , page: , stat: ,