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 STROKE PATHOPHYSIOLOGY, DIAGNOSIS, TREATMENT AND PREVENTION

Dr. Elaine Skalabrin MD

Objectives:

1.      To understand the pathophysiology of stroke.

2.      To understand the importance of stroke subtyping.

3.      To become familiar with clinical stroke syndromes

4.      To review the current recommendations of stroke management and prevention.

Definition:

·        Stroke = Acute disruption of blood flow to the brain leading to focal neurologic deficits

·        TIA (transient ischemic attack) = Acute disruption of blood flow to the brain leading to focal neurologic deficits lasting less than 24 hours (usually 10 – 30 minutes)

Epidemiology

·        700,000 stroke per year

·        Leading cause of disability in USA

·        Incidence increases with age

·        African Americans>Hispanics> Whites

Stroke subtypes:

·        Ischemic

·        Hemorrhagic

Ischemic Stroke Subtypes:

·        Thrombotic: a blood clot forms within a blood vessel in the brain

·        Embolic: a blood clot forms within the heart or a major blood vessel of the brain

·        Lacunar: a very small blood vessel of the brain progressively narrows until completely occluded

·        Cryptogenic: the mechanism for the stroke is unknown

Anatomy Review:

·        Internal carotid artery

·        Middle cerebral artery

·        Anterior cerebral artery

·        Basal artery

·        Vertebral artery

·        Communicating arteries

Anterior cerebral artery:

·        Weakness of right lower limb (right side of face usually spared, and right upper limb less affected than right lower limb)

·        Speech disturbance (dysphasia)

·        Apraxia of left (non paralyzed) side of body (apraxia = inability to properly execute movements despite normal strength)

·        Disturbance of bladder control

·        Confusion initially, later personality change may occur

Middle cerebral artery – non-dominant (right hemisphere stroke in right handed person):

·        Weakness of left side of face, arm and (to lesser extent) leg

·        Left sided sensory disturbance

·        Visual disturbance: loss of lower left part of field of vision of each eye (homonymous left lower quadrantanopia)

·        Confusion, sensory and/or motor neglect

Middle cerebral artery – dominant (left hemisphere stroke in right handed person):

·        Weakness of right side of face and right arm (right leg less affected)

·        Sensory impairment right side of body

·        Speech disturbance (dysphasia), including difficulty in comprehending written words and writing

·        Visual field loss in lower right quadrant of visual field of each eye (homonymous right lower quadrantanopia)

Vertebrobasilar system:

·        Basilar artery:

·        Complete obstruction of the basilar artery is usually rapidly fatal, with rapid onset of unconsciousness and deepening coma. 

·        Small branch occlusion have a variety of clinical features

In the pons:   Sixth nerve under action on the side of stroke, weakness of arm and leg on side opposite stroke, Impaired conjugate gaze in the midbrain: Third nerve impairment on side of stroke, weakness of arm and leg on side opposite to stroke

·        Posterior cerebral artery:

·        Loss of half of the field of vision on the side opposite to the stroke (homonymous hemianopia)

·        Ischemic injury to the thalamus may result in unpleasant, burning pain over opposite side of body (“thalamic syndrome”)

·        Vertebral artery:

·        Vertigo at onset

·        Cerebellar incoordination of arm and leg on the same side

·        Loss of pain and temperature sense of the half of the face that is on the same side as the stroke, and of the trunk and limbs on the side opposite to the stroke

·        Difficulty in swallowing and speaking

·        Horner’s syndrome (small pupil, mild drooping of eyelid and lack of sweating of face on same side as stroke)

Lacunar syndromes:

·        Pure motor

·        Pure sensory

·        Sensorimotor

·        Ataxia hemiparesis

·        Dysarthria clumsy-hand

Evaluation of acute stroke patients:

·        Medical evaluation

·        Neurologic evaluation

·        Mental status

·        Cranial nerves

·        Motor

·        Sensory

·        Coordination

·        Gait

·        Laboratories

·        Imaging

·        Non-contrast head CT

·        MRI

·        Diffusion/perfusion weighting

·        MRA

·        Carotid ultrasound

·        Echocardiogram/EKG

·        Angiography

Treatment of acute stroke patients:

·        Urgent general supportive care

·        Management of serum glucose

·        Management of hypertension

·        Seizure management

·        Management of brain edema

·        Medications:

·        Intravenous t-PA

·        Intra-arterial t-PA

·        Anticoagulation

Complications of acute stroke:

·        Thrombotic complications

·        Medical complications

Prevention of stroke:

·        Risk factors:

·        Hypertension

·        Cigarette smoking

·        Alcohol use

·        Physical activity

·        Diet

·        High cholesterol (hyperlipidemia)

·        Atrial fibrillation

·        Transient ischemic attacks

·        Treatment/medications:

·        Antiplatelet therapy

·        Anticoagulation

·        Other

 

References:

Goldstein LB et al, Primary Prevention of Ischemic Stroke.  Circulation. 2001;103:163-182.

Adams HP et al, Guidelines for the Management of Patients with Acute Ischemic Stroke. Circulation. 90(3);1588-1601

Albers GW et al, Antithrombotic and Thrombolytic Therapy for Ischemic Stroke. Chest. 2001; Jan;119(1 Suppl):300S-320S.

Albers GW et al, Guidelines for the Management of Transient Ischemic Attacks. Stroke. 1999 Nov;30(11):2502-11.

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                                              Last updated:  10/05/2002                                                          © 2000-2002 John Rose, MD  University of Utah School of Medicine