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Chapter 141: Stroke Syndromes and Spontaneous Subarachnoid Hemorrhage

Steven Go

INTRODUCTION

Stroke encompasses any disease process that interrupts normal blood flow to the brain. Ischemic strokes (87%) are more common than intracerebral hemorrhage (10%) or nontraumatic subarachnoid hemorrhage (SAH) (3%) (Table 141–1). A transient ischemic attack (TIA) is a transient episode of neurological dysfunction caused by ischemia but without an acute infarction of brain tissue. TIA episodes typically lasts less than 1 to 2 hours, but duration of symptoms alone can be unreliable in discriminating between TIA and stroke as they are similar disease processes on a continuum of severity.

Table 141-1

Stroke Classification

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Table 141-1

Stroke Classification
Stroke Type Mechanism Major Causes Clinical Notes
Ischemic
Thrombotic Narrowing of a damaged vascular lumen by an in situ process—usually clot formation

Atherosclerosis

Vasculitis

Arterial dissection

Polycythemia

Hypercoagulable state

Infection (human immunodeficiency virus infection, syphilis, trichinosis, tuberculosis, aspergillosis)

Symptoms often have gradual onset and may wax and wane.

Common cause of transient ischemic attack.
Embolic Obstruction of a normal vascular lumen by intravascular material from a remote source

Valvular vegetations

Mural thrombi

Paradoxical emboli

Cardiac tumors (myxomas)

Arterial-arterial emboli from proximal source

Fat emboli

Particulate emboli (IV drug use)

Septic emboli

Typically sudden in onset.

Account for 20% of ischemic strokes.
Hypoperfusion Low–blood flow state leading to hypoperfusion of the brain

Cardiac failure resulting in systemic hypotension

Diffuse injury pattern in watershed regions.

Symptoms may wax and wane with hemodynamic factors.
Hemorrhagic
Intracerebral Intraparenchymal hemorrhage from previously weakened arterioles

Hypertension

Amyloidosis

Latrogenic anticoagulation

Vascular malformations

Cocaine use

Intracranial pressure rise causes local neuronal damage.

Secondary vasoconstriction mediated by blood breakdown products or neuronal mechanisms (diaschisis) can cause remote perfusion changes.

Risks include advanced age, history of stroke, and tobacco or alcohol use.

More common in those of Asian or African descent.
Nontraumatic subarachnoid Hemorrhage into subarachnoid space

Berry aneurysm rupture

Vascular malformation rupture

May be preceded by a sentinel headache (“warning leak”).

CLINICAL FEATURES

Specific findings in patients with ischemic or hemorrhagic stroke depend on the regions of the brain that are compromised and the severity of the insult (Table 141–2).

Table 141-2

Anterior and Posterior Circulation of the Brain

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Table 141-2

Anterior and Posterior Circulation of the Brain
Circulation Major Arteries Major Regions of Brain Supplied
Anterior (internal carotid system) Ophthalmic Optic nerve and retina
Anterior cerebral Frontal pole
Anteromedial cerebral cortex
Anterior corpus callosum
Middle cerebral Frontoparietal lobe
Anterotemporal lobe
Posterior (vertebral system) Vertebral Brainstem
Posteroinferior cerebellar Cerebellum
Basilar Thalamus
Posterior cerebral Auditory/vestibular structures
Medial temporal lobe Visual occipital cortex

Typical symptoms of anterior cerebral artery involvement include contralateral leg weakness and sensory changes. A middle cerebral artery stroke presents with contralateral hemiparesis (arm > leg), facial plegia, and sensory loss. Aphasia is often present if the dominant hemisphere (usually left) is affected. Inattention, ...

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