0071643192.pdf

■ Optic nerve and retina

■ Deep gray matter

■ Posterior circulation (from vertebrobasilar arteries, 20% of CBF)

■ Medial aspect of temporal lobes

■ Visual occipital cortex

■ Thalamus

■ Brainstem

■ Upper spinal cord

■ Cerebellum

■ Auditory and vestibular function

■ Circle of Willis

■ Connection between anterior and posterior circulations

Ischemic Stroke

Ischemic stroke may be divided into three types: thrombotic, cardioembolic

and hypoperfusion states.

THROMBOTICSTROKE

CAUSES

Thrombosis is the most common cause of stroke in the United States and typi-

cally results from clot formation at the site of an ulcerated atherosclerotic plaque.

Other causes include:

■ Vessel narrowing from vasculitis, dissection, infectious disease, vasospasm

■ Thrombophilia from hypercoagulable states

■ Sickle cell disease

■ Polycythemia

Symptoms generally come on gradually and may be preceded by transient

ischemic attacks (TIAs) affecting the same region as the stroke.

A subset of thrombotic stroke is the lacunar stroke. This is a stroke of a small

terminal vessel, typically deep in the subcortical cerebrum, basal ganglia,

internal capsule, thalamus, corona radiate, or brainstem. There is higher inci-

dence in African Americans, Mexican Americans, Hong Kong Chinese, and

patients with hypertension and diabetes.

CARDIOEMBOLICSTROKE

CAUSES

Occurs when intravascular material (eg, clot) from a proximal source travels

to the cerebral circulation, causing obstruction

Types of emboli include:

■ Cardiac (mural thrombus, valvular vegetations, cardiac tumors)

■ Venous thrombosis (in the presence of a ventricular or atrial septal defect)

■ Proximal aortic or carotid atherosclerotic plaque

■ Fat (from a broken bone)

■ Air (air embolism)

■ Particulate matter (eg, talc from injection drug use)

Onset is typically sudden and maximal.

NEUROLOGY

The most common source of

embolic stroke is mural

thrombus in patients with

atrial fibrillation.