Ischemic strokes are due to restrictions of the blood flow in the vessels inside the brain. The restriction of blood flow deprives the brain tissue of oxygen and glucose. Restrictions in blood flow may be caused by:

Hemorrhagic strokes are due to bleeding from the blood vessels inside the brain itself (intraparenchymal). Bleeding may be caused by:

There are additional types of hemorrhage affecting the brain but not in the brain itself. Although these are not strokes, they are mentioned briefly here.

Transient Ischemic Attack ( TIA )

TIA is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarct. Older definitions specified that symptoms lasted less than 24 h, but one-third to one-half of individuals with traditionally defined TIAs exhibit new infarct on advanced imaging procedures. Therefore, it is impossible to define a specific time cutoff that can accurately distinguish whether a symptomatic ischemic event will result in brain injury. Rather, imaging is needed to differentiate a symptomatic ischemic event with infarct (stroke) vs. a symptomatic ischemic event without infarct (TIA). It is suggested that the term acute neurovascular syndrome be used until diagnostic imaging is completed or if diagnostic imaging is not performed all.

Approximately 240,000 TIAs occur in the U.S. annually [1]. For people who have a TIA:

Approximately 795,000 Americans experience a stroke each year. Over the course of a lifetime, 4 out of 5 American families will be touched by stroke. There are an estimated 6.8 million adult stroke survivors in the U.S. The estimated national direct and indirect cost of stroke is $62.7 billion annually [4].

For individuals with stroke, 8 % of ischemic strokes and 38 % of hemorrhagic strokes result in death within 30 days [5]. Stroke is the fourth leading cause of death in America and a leading cause of adult disability [6].

Acute Inpatient Medical Care

Public health campaigns providing education and advice about stroke have focused on using an acronym to help people recognize and respond to stroke:

Time is of the essence because most strokes are ischemic, most ischemic strokes are embolic, and most embolic strokes are caused by blood clots. Blood clots have the potential to be addressed in the early stages of a stroke before extensive damage occurs.

On presentation to a hospital emergency department, after any needed initial stabilization, a head CT is performed. This quickly shows whether there is a hemorrhage in the brain, as acute blood is quite bright on CT. However, if there is an ischemic stroke, CT will usually not show any abnormalities until 24 h later . This rapidly differentiates ischemic from hemorrhagic stroke. If the patient has clear stroke-like symptoms, and the CT shows no bleeding, a clot embolus is presumed.

Tissue plasminogen activator (t-PA) can be injected within the first four hours following ischemic stroke to dissolve blood clots. However, if the stroke occurred more than four hours previously, t-PA can increase the risk of hemorrhagic conversion, and is not recommended. However, recent research [8] indicates that the increased risk of hemorrhage is due to damage to the blood–brain barrier (BBB) in the area of the stroke in some patients. A new MRI sequence has been shown to differentiate those patients who had stroke involving damage to the BBB, and therefore should not be given anticoagulant treatment, from those patients who had stroke without damage to the BBB, and therefore may be given anticoagulant treatment even beyond the 4-h time window [8].

An additional procedure, performed only at a few centers, is thrombectomy, where a catheter is introduced through the femoral artery, through the aorta, heart, and internal carotid artery, into the brain to the site of the blockage, and then the clot is mechanically grabbed and pulverized or pulled out.