Ischemic Stroke

An ischemic stroke occurs when a blocked vessel prevents blood—and therefore oxygen and nutrients—from reaching the cells and tissues of the brain; without blood flow, damage to brain cells can occur quickly. Our physicians are experienced in medical and surgical stroke treatments that may mitigate effects of stroke and aid in prevention of future strokes.

Standard surgical interventions include endovascular stent retrieval or intra-arterial thrombolysis; carotid endarterectomy; and carotid angioplasty and stenting. Whenever possible, strokes should be treated by an experienced stroke team at a comprehensive stroke center, like the one at Columbia University Irving Medical Center/NewYork-Presbyterian Hospital.

Stroke is a leading cause of death and disability in the United States. Ischemic strokes account for about 87 percent of all strokes. The remaining 13 percent are hemorrhagic strokes, which are caused by bleeding in the brain.

In an ischemic stroke, the blocked blood vessel may be either a carotid artery or a cerebral artery.


The symptoms of an ischemic stroke depend on the size and location of the blockage. Symptoms may include:

  • Sudden confusion and loss of coordination
  • Sudden trouble seeing (blurry vision, double vision or no vision) in one or both eyes
  • Sudden weakness or numbness in an arm, a leg or the face
  • Sudden severe headache

Quick treatment for a stroke is essential for the best possible outcome. One way to remember common signs of a stroke is the acronym FAST:

  • Face drooping
  • Arm weakness (especially on one side)
  • Speech slurred
  • Time to call 911

Any of these symptoms should prompt a call to 911, even if the symptoms subside. Stroke symptoms that go away on their own are signs of a transient ischemic attack (TIA). A TIA may indicate that the patient has increased risk for a stroke with permanent consequences.


To diagnose a stroke, doctors will order an imaging test like computed tomography (CT) or magnetic resonance imaging (MRI) to be performed immediately. CT and MRI scans are both non-invasive means of producing images of the body’s tissues. The MRI uses magnets and radio waves, while the CT uses a computer and X-rays. CT scans are more commonly performed in an emergency like a stroke, because they can often provide images more quickly, and they can be performed in patients who have implanted metallic devices like pacemakers or aneurysm clips.

Further testing depends on the outcome of the initial scans. Possible tests include:

  • Carotid duplex scanning, which uses two kinds of sound waves to form pictures of the carotid arteries and provide information about blood flow
  • Digital subtraction angiography, which uses a computer and a special dye to form images of blood vessels in the brain
  • Single-photon emission CT (SPECT), which uses a CT scan to create 3-D images that can show which brain areas are suffering from lack of oxygen
  • Diffusion-weighted imaging (DWI), which uses an MRI to detect brain areas that are swollen and injured
  • Blood tests to check clotting, blood sugar, toxins, organ function and/or other factors

Risk Factors

The major cause of ischemic stroke is atherosclerosis. In this condition, deposits called plaques build up inside artery walls. The walls become thick and stiff, and the space for blood flow narrows.

Ischemic stroke can occur when a plaque bursts in the wall of a cerebral or carotid artery. A burst plaque begins a cascade of reactions that results in a blood clot inside the vessel. This clot can block blood flow to the brain. This type of stroke is called a thrombotic stroke.

An ischemic stroke can also be caused when a piece breaks off from a blood clot elsewhere in the body—often in the heart. The clot may travel through the bloodstream until it reaches a vessel too narrow for it to pass through. There it may lodge and block blood flow. This is called an embolic stroke.


Stroke treatment can be medical, surgical or both.

One device that surgeons can use to treat ischemic stroke is called a stent retriever. This tiny instrument has two main components: a stent that props an artery open, and a retriever that extracts the clot. A highly trained endovascular specialist can thread this system through the blood vessels to the clot. This treatment must be begun quickly to have the best effect, and it is not right in all cases.

Another option that uses the blood vessels as a pathway to the clot is intra-arterial thrombolysis. In this treatment, clot-dissolving medication is delivered directly to the clot. An endovascular specialist threads a thin tube through the blood vessels to the site of the clot. As with much stroke treatment, this treatment must be performed quickly to have the best effect.

If the ischemic stroke was due to carotid artery disease, it may be appropriate to treat the blocked arteries to prevent a second stroke. One treatment for carotid artery disease is carotid endarterectomy (CEA). In this procedure, a neurosurgeon opens the carotid arteries and removes the blockages. Another treatment for carotid artery disease is carotid angioplasty and stenting (CAS). This procedure widens the narrowed artery with a balloon-like instrument and props it open with a stent. It is performed through the blood vessels and does not require open surgery. Read more about the options for carotid artery surgery.