Stroke : Symptoms, Pathophysiology, Diagnosis, And Treatment
Stroke is a term used to describe an abrupt onset of focal neurologic deficit that lasts at least 24 hours and is presumed to be of vascular origin. Transient ischemic attacks (TIAs) are focal ischemic neurologic deficits lasting less than 24 hours and usually less than 30 minutes.
Pathophysiology of Stroke :
RISK FACTORS FOR STROKE
Nonmodifiable risk factors for stroke include increased age, male gender, race (African American, Asian, Hispanic), and heredity.
The major modifiable risk factors include hypertension
and cardiac disease (e.g., coronary artery disease, heart failure, left ventricular hypertrophy, atrial fibrillation).
Other major risk factors include transient ischemic attacks, diabetes
mellitus, dyslipidemia, and cigarette smoking.
Diagnosis of Stroke :
Computerized tomography (CT) head scan will reveal an area of hyperintensity (white) in an area of hemorrhage and will be normal or hypointense (dark) in an area of infarction. The area of infarction may not be visible on CT scan for 24 hours (and rarely longer).
Magnetic resonance imaging (MRI) of the head will reveal areas of ischemia with higher resolution and earlier than the CT scan. Diffusion-weighted imaging (DWI) will reveal an evolving infarct within minutes.
Carotid Doppler studies will determine whether there is a high degree of stenosis in the carotid arteries.
The electrocardiogram (ECG) will determine whether atrial fibrillation is present.
A transthoracic echocardiogram (TTE) can detect valve or wall motion abnormalities that are sources of emboli to the brain.
A transesophageal echocardiogram (TEE) is a more sensitive tests for left atrial thrombus. It is also effective in examining the aortic arch for atheroma, another potential source of emboli.
Transcranial Doppler (TCD) can determine the presence of intracranial arterial sclerosis (e.g., middle cerebral artery stenosis).
Laboratory tests for hypercoagulable states should only be done when the cause of the stroke cannot be determined based on the presence of well-known risk factors. Protein C, protein S, and antithrombin III are best measured in steady state rather than in the acute stage. Antiphospholipid antibodies are of higher yield but should be reserved for patients aged less than 50 years and those who have had multiple venous or arterial thrombotic events or livedo reticularis.
The Treatment of Stroke :
In acute ischemic stroke, surgical interventions are limited. However, surgical decompression can be lifesaving in cases of significant swelling associated with cerebral infarction. An interdisciplinary approach to stroke care that includes early rehabilitation is very effective in reducing long-term disability. Carotid endarterectomy is effective in reducing stroke incidence and recurrence in appropriate patients. Carotid stenting may be effective in reducing recurrent stroke risk in patients at high risk of complications during endarterectomy.
In subarachnoid hemorrhage due to a ruptured intracranial aneurysm or arteriovenous malformation, surgical intervention to clip or ablate the vascular abnormality substantially reduces mortality from bleeding. The benefits of surgery are less well documented in cases of primary intracerebral hemorrhage. In patients with intracerebral hematomas, insertion of an intraventricular drain with monitoring or intracranial pressure is commonly performed. Surgical decompression of a hematoma is a controversial exception as a last resort in life-threatening situations.
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