Stroke Assessment: The Two Types of Strokes

Acute stroke refers to the acute neurologic impairment that follows an interruption in blood supply or a rupture of a blood vessel to a specific region of the brain. Following stroke assessment, experts and clinicians most often classify strokes as either ischemic or hemorrhagic. The causes of acute stroke are numerous; however, the initial therapy is based on the presence or absence of bleeding, as well as a presumed ischemic stroke regardless of cause.

Ischemic stroke

In an ischemic stroke (87 percent of all strokes), interruption in blood supply is caused by blockage of an artery to a region of the brain, and rarely lead to death within the first hour. Ischemic strokes can be defined on the basis of etiology and duration of symptoms, and are generally subdivided into the following five categories:

Thrombotic stroke: An acute clot that occludes an artery is superimposed on chronic arterial narrowing, acutely altered endothelial lining, or both.
Embolic stroke: Intravascular material, most often a blood clot, separates from a proximal source and flows through an artery until it occludes an artery in the brain. Many of these originate from the heart in patients with atrial fibrillation, valvular heart disease and acute myocardial infarction.
Transient ischemic attack (TIA): Sometimes called “mini-stroke,” TIA involves any focal neurologic deficit that resolves completely and spontaneously within one hour. TIA generally lasts less than 15 minutes.
Reversible ischemic neurologic deficit (RIND): Any focal neurologic deficit that resolves completely and spontaneously within 24 hours. Any patient with a persistent neurologic deficit beyond 24 hours is said to have suffered a stroke.
Hypoperfusion stroke: A more global pattern of brain infarction that results from low blood flow or intermittent periods of no flow. Hypoperfusion stroke often occurs in patients who recover cardiac function after sudden cardiac arrest.

Prehospital stroke care providers will often refer to the Suspected Stroke Algorithm to identify potential stroke. Upon arrival at an emergency department (ED) or stroke hospital, lab work and patient imaging will occur for further stroke assessment. If a CT scan shows no hemorrhage, the probability of acute ischemic stroke is high, and the physician or stroke team should review the inclusion and exclusion criteria for IV fibrinolytic therapy (tPA) and perform a repeat neurologic examination. If the patient’s neurologic signs are spontaneously clearing and function is rapidly improving toward normal levels, fibrinolytic administration is not recommended.

A major benefit of tPA treatment is improved neurological outcome without mortality. Several studies have documented a higher likelihood of good to excellent functional outcome when tPA is administered to adults with acute ischemic stroke within three hours of symptom onset. A major risk of tPA, however, includesintracranial hemorrhage and death. The physician must verify that there are no exclusion criteria, consider the risks and benefits to the patient and be prepared to monitor and treat any potential complications.

Hemorrhagic Stroke

Hemorrhagic strokes (13 percent of all strokes) occur when a blood vessel in the brain suddenly ruptures with hemorrhage into the surrounding tissue. Stroke assessment reveals two types of hemorrhagic stroke, characterized by the location of the arterial rupture:

Intracerebral hemorrhagic stroke (10 percent): Occurs when blood leaks directly into the brain parenchyma, usually from small intracerebral arterioles damaged by chronic hypertension, the most common cause of intracerebral hemorrhage. Among the elderly, amyloid angiopathy appears to play a major role in intracerebral hemorrhage.
Subarachnoid hemorrhagic stroke (3 percent): Occurs when blood leaks from a cerebral vessel into the subarachnoid space. If the rupture occurs in a cerebral artery, the blood is released at systemic arterial pressure, causing sudden, painful and dramatic symptoms. Aneurysms cause most subarachnoid hemorrhages, while arteriovenous malformations cause approximately 5 percent of subarachnoid hemorrhages.

Hemorrhagic stroke symptoms mirror those of ischemic stroke, although confirmation can be conclusively attained through medical imaging upon comprehensive stroke assessment upon arrival at a hospital. If the initial CT scan shows intracerebral or subarachnoid hemorrhage, the responsible physician should immediately consult a neurosurgeon and initiate appropriate actions for acute hemorrhage.

For more information on stroke certification requirements and stroke training, visit the overview of stroke courses offered online.

The information included in this article is based on the 2020 guidelines for CPR, first aid and advanced cardiovascular care.