Acute Ischemic Stroke
The Bernard and Irene Schwartz Neurointerventional Radiology physicians, Drs. Tibor Becske and Maksim Shapiro, function as an integral part of the comprehensive NYU Comprehensive Stroke Care Center team which includes stroke neurologists, neurointensivists, rehabilitation specialists, anesthesiologists, neurosurgeons, speech and swallow specialists, stroke nurses, and others. The purpose of the team is to function in hyper-acute diagnosis and treatment of stroke.
The NYULMC has a long history of excellence in stroke, becoming Manhattan’s first stroke center in 2005, and receiving numerous recognitions and awards, such the American Heart Association/American Stroke Association Gold Plus® designation, the “Target: Stroke Recognition” award by the American Heart and Stroke association, among others. NYU Langone was also named one of the top ten hospitals nationally for its neurology and neurosurgery programs in the 2013-14 US News & World Report Best Hospitals rankings. Also, since 1989, Rusk Rehabilitation Institute, which provides rehabilitation services for our stroke patients, has been ranked by US News & World Report one of the top ten rehabilitation programs in the nation and number one in New York.
What is stroke?
Stroke is sudden onset of brain dysfunction due to interruption of brain blood flow. Despite tremendous advances in medical treatment of stroke-causing conditions, such as hypertension, diabetes, and smoking, stroke remains an extremely common problem. There are two broad kinds of stroke – ischemic and hemorrhagic. Hemorrhagic stroke is caused by sudden bleeding into the brain or its coverings. Different types of hemorrhagic stroke include parenchymal (brain) bleeding and subarachnoid hemorrhage (SAH, bleeding around the brain, often caused by rupture of brain aneurysms). Ischemic stroke (the majority) is caused by interruption of blood flow to the brain. This can happen when a thrombus (clot) forms in an artery in the brain, blocking it and interrupting blood flow. Other times, the clot first forms outside the brain, such as in the heart of a patient with atrial fibrillation. The clot then breaks off and travels with blood flow, lodging somewhere else. When this kind of clot travels to and closes an artery supplying the brain, severe strokes often result because of the frequently large size of the clot. Other causes of ischemic stroke include artery dissections (tears in artery walls) or acute closure of a diseased carotid artery in the neck.
Patients with acute onset of ischemic stroke can frequently benefit from rapid in-hospital treatments. Time is brain! The brain is not designed to survive without oxygen and nutrients for any extended length of time. Usually, there is perhaps a window of only a few hours or less to save the brain tissue at risk by removing the clot to restore blood flow. Sometimes, this can be done by injecting a clot-busting drug called tissue Plasminogen Activator (t-PA) into the patient’s veins within the first 4.5 hours of stroke onset, allowing it to circulate through the body, dissolving clots everywhere. Although technically the drug can be given within 4.5 hours, the sooner the better! Patients that make the most improvement are often ones who were fortunate enough to be treated within 1 hour of symptom onset. Although some patients will be harmed by t-PA (about 6% will have major bleeding, a side effect of dissolving clots), fully 30% will benefit from it, achieving significant stroke recovery they otherwise would not have had. Therefore, most physicians now strongly recommend giving this medication as soon as possible to patients who are eligible for it.
Unfortunately, not everyone with ischemic stroke is eligible. Many patients arrive too late. In some, the time of stroke onset cannot be established with certainty – a stroke can begin during sleep, precluding accurate timing (the problem with giving the drug too late is that the brain is already damaged and there is no benefit, while the risk of bleeding remains). Other “exclusion criteria” – reasons while tPA cannot be given – are patients who take Coumadin or other blood thinners, patients with recent surgery, and others. Finally, many patients with large clots, such as those coming from the heart, are unlikely to improve after tPA, even when it is given early – the clots are too big for tPA to dissolve.
For these patients, as well as for some others, there is a possibility of removing the clot directly by placing a catheter into the blocked artery and either dissolving the clot by injecting tPA and other powerful clot-dissolving medicationsdirectly into the clot, or by mechanically pulling the clot out of the body.
The role of The Bernard and Irene Schwartz Interventional Neuroradiology physicians is to perform these kinds of interventional procedures, called transarterialthrombectomy and/or thrombolysis. Using a series of catheters inserted into an artery under x-ray guidance, as part of a Cerebral Angiogram, the physicians can reach the blocked vessel and use a variety of tools and medications to remove or fragment the clot. Some recently introduced and highly effective devices for clot retrieval include The Solitaire, Trevo, and Penumbra devices which, overall, allow restoration of meaningful brain blood flow in more than 80% of cases – a vast improvement over what used to be the case at the turn of the 21st century. The techniques and devices are constantly evolving and improving, so that more and more arteries can be opened safely and effectively, as seen in the following case, where an occluded (closed) artery was reopened.
The challenge increasingly faced by the stroke team is to identify which patients will benefit from these interventions. Unfortunately, many arrive too late, when opening the artery no longer helps the brain which has already suffered the stroke. Other patients, even when arriving time, do not have sufficient remaining brain circulation, so that even after a short amount of time the brain tissue can no longer be salvaged. To this end, we sometimes employ advanced imaging techniques such as CT Perfusion to identify which patients stand to benefit from our interventions, as is seen in image below:
It is also the reason why, in the arena of acute stroke, we place the utmost emphasis on cohesive functioning of the team as a whole, so that intervention can be organized and performed in the shortest possible amount of time. Nevertheless, it is important to keep in mind that despite our best efforts, acute interventions can still only help a minority of patients with stroke. Even when intervention is successful, patients with stroke usually remain very ill for some time, requiring vigilant care by other members of the team, which include stroke intensivists, stroke neurologists, superb nursing support staff, swallow specialists, physical and occupational therapists, and many others. For many patients, recovery will be a slow, painstaking process, overseen by specialists in rehabilitation medicine, including NYU’s highly acclaimed Rusk Rehabilitation Center, which is located within the Hospital for Joint Diseases.
To reach our on-call stroke team, call 855-NYU-2225
The Interventional Neuroradiologists Drs. TiborBecske and Maksim Shapiro can be reached by calling 212-263-6008