Overview of stroke

Last updated: November 2, 2023

Summarytoggle arrow icon

A stroke is an acute neurologic condition resulting from a disruption in cerebral perfusion, either due to ischemia (ischemic strokes) or hemorrhage (hemorrhagic strokes). Hemorrhagic strokes are further classified as intracerebral or subarachnoid. Systemic hypertension and other cardiovascular diseases are common risk factors for both ischemic and hemorrhagic strokes. Clinically, strokes are characterized by the acute onset of focal neurologic deficits, including hemiparesis, paresthesias, and hemianopsia. The pattern of clinical features is dictated by the affected vessel. Distinguishing between ischemic and hemorrhagic strokes based on physical examination is difficult and requires initial evaluation with a noncontrast head CT. Further neurovascular imaging may be required before deciding on treatment options. In ischemic strokes, immediate revascularization of the affected vessel is vital to preserve brain tissue and prevent further damage. Hemorrhagic strokes are treated with supportive measures and neurosurgical evacuation of blood. Long-term management of all types of stroke focuses on the management of modifiable risk factors (i.e., hypertension and atherosclerosis).

For more information, see respective articles “Ischemic stroke,” “Intracerebral hemorrhage,” and “Subarachnoid hemorrhage.”

Definitiontoggle arrow icon

Overviewtoggle arrow icon

The following table focuses on nontraumatic cerebral ischemia and intracranial hemorrhage.

Ischemic stroke Intracerebral hemorrhage Subarachnoid hemorrhage
Risk factors
Clinical features
  • Noncontrast head CT to rule out hemorrhage
  • MRI
Findings on noncontrast head CT

For both ischemic and hemorrhagic strokes, age is the most important nonmodifiable risk factor and arterial hypertension is the most important modifiable risk factor.

Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon


Stroke symptoms by affected vesseltoggle arrow icon

Clinical features of stroke by affected vessel
Affected vessel Clinical features [5][6]

Middle cerebral artery (MCA) (most commonly affected vessel)

  • Contralateral weakness and sensory loss more marked in the upper limbs and lower half of the face than in lower limbs
  • Gaze deviates toward the side of infarction
  • Contralateral homonymous hemianopia without macular sparing or superior/inferior quadrantanopia [6][7]
  • Aphasia if in dominant hemisphere (usually left MCA territory)
  • Hemineglect if in nondominant hemisphere (usually right MCA territory)
    • Unawareness of and unresponsiveness to unilateral stimuli due to a brain unilateral injury, most commonly strokes (not due to a primary motor or sensory lesion)
    • Typically associated with right hemisphere damage resulting in neglect (esp. visual) of the left side [8]
    • The lesion is usually contralateral to the stimuli
      • Motor neglect
      • Sensory or perceptual neglect
Anterior cerebral artery (ACA)
Posterior cerebral artery (PCA)
Posterior inferior cerebellar artery
Anterior inferior cerebellar artery
Lenticulostriate arteries (penetrating arteries)
Basilar artery
Extracranial arteries Internal carotid artery
Common carotid artery
Vertebral artery
Anterior spinal artery


Stroke symptoms by affected regiontoggle arrow icon

Lacunar syndromes [6][16]

Overview of lacunar strokes
Lacunar stroke type Location Clinical features
Pure motor stroke
Pure sensory stroke
Sensorimotor stroke
Ataxic hemiparesis
  • Ipsilateral weakness with impaired coordination (e.g., ataxia, gait instability) [17][18]
Dysarthria-clumsy hand syndrome
  • Contralateral, involuntary, large flinging movements of the arm or leg

Infarction of the posterior limb of the internal capsule is the most common type of lacunar stroke and may manifest clinically with pure motor stroke, pure sensory stroke (rare), sensorimotor stroke, dysarthria-clumsy hand syndrome, and/or ataxic hemiparesis.

Brainstem syndromes [6][19]

General considerations

Midbrain syndromes [20][21][22]

Pontine syndromes

Overview of pontine syndromes
Syndrome Affected vessel Affected structures Resulting symptom

Ventral pontine syndrome (Millard-Gubler syndrome)

Lateral pontine syndrome (Marie-Foix syndrome)
Inferior medial pontine syndrome (Foville syndrome)
Locked-in syndrome

Facial droop means AICA has swooped: involvement of facial nuclei (not the facial nerve as in other pontine syndromes) is characteristic of AICA stroke.

Medullary syndromes

Overview of medullary syndromes
Syndrome Affected vessel Affected structures Resulting symptom
Medial medullary syndrome (Dejerine syndrome) Paramedian branches of the anterior spinal artery and/or vertebral arteries Nucleus and fibers of the hypoglossal nerve Ipsilateral tongue palsy (deviation of the tip to the ipsilateral side)
Corticospinal tract Contralateral hemiparesis
Medial lemniscus Contralateral decrease in proprioception
Lateral medullary syndrome (Wallenberg syndrome) Posterior inferior cerebellar artery Nucleus ambiguus (CN IX, X, XI)

Ipsilateral bulbar palsy (dysphagia, dysphonia, hiccups, decreased gag reflex)

Vestibular nuclei Ipsilateral nystagmus and vertigo
Lateral spinothalamic tract Contralateral decrease in pain and temperature sensations in the trunk and limbs
Spinal trigeminal nucleus Ipsilateral decrease in pain and temperature sensations in the face
Inferior cerebellar peduncle Ipsilateral limb ataxia and dysmetria
Sympathetic fibers Ipsilateral Horner syndrome

To remember the cause and the symptoms of the lateral medullary syndrome: Try not to pick a (PICA) horse (hoarseness) that can't eat (dysphagia).

Clinical features of strokes affecting other regions

Overview of clinical features of strokes affecting other regions
Location of lesion Clinical features [6][13]
Watershed border-zone


Diagnosticstoggle arrow icon

Initial evaluation

Imaging [27][28]

Laboratory evaluation

Laboratory studies should not delay imaging for patients with acute stroke. [27]

Treatmenttoggle arrow icon


If symptoms of a suspected ischemic stroke began less than 4.5 hours prior to presentation and there are no signs of intracranial bleeding, begin reperfusion therapy immediately.

Stabilization and monitoring [27]

See “Secondary brain injury and neuroprotective measures.”

Blood pressure management [27][30]

Nitrates should be avoided because they can increase intracranial pressure.


Complicationstoggle arrow icon

Medical complications

Neurologic complications [33]

All strokes

Ischemic stroke

Hemorrhagic stroke

We list the most important complications. The selection is not exhaustive.

Preventiontoggle arrow icon

Stroke prevention focuses on reducing modifiable risk factors and treating conditions that increase the risk of cerebrovascular ischemia and/or hemorrhage. In patients with risk factors for both ischemic and hemorrhagic stroke, the risks and benefits of each prevention strategy should be carefully weighed.

Primary prevention

The two main modifiable risk factors for the primary prevention of hemorrhagic stroke are hypertension and the use of anticoagulants. [39]

Prevention of stroke recurrence

Individuals often have overlapping risk factors for both ischemic stroke and hemorrhagic stroke; assess recurrence risk with a thorough history and examination, laboratory studies, and possibly imaging. [42]

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Referencestoggle arrow icon

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