Evaluation Guidelines

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The goals of the diagnostic evaluation are to establish the diagnosis of ischemic or hemorrhagic cerebrovascular disease as a cause of the patient's symptoms and to determine the underlying cause of the event. Early diagnosis and management in the first few hours after stroke are critical. Since proper management begins with an accurate diagnosis, it is paramount to differentiate between cerebral infarction and hemorrhage. The tests that may assist with diagnosis are detailed in Tabie.J.iiS . There are a number of potential etiologies of cerebral infarction and hemorrhage that need to be considered ( ,Tab!e.S,..2.2..-.3 and 22-.4 and see Chapter .4,5 .

Neuroimaging. In all patients with suspected ischemic stroke, an unenhanced computed tomogram (CT) of the brain is the first test to differentiate between infarction and hemorrhage. In addition, other disorders that mimic acute cerebrovascular disease must be excluded, including tumors, abscesses, and subdural hematomas. Intravenous contrast-enhanced CT is needed only when these diagnoses are a consideration. Thin CT cuts through the posterior fossa should be done if posterior fossa pathology is suspected. Magnetic resonance imaging (MRI) is superior to CT in cerebral ischemia, particularly in the evaluation of ischemic areas in the posterior fossa.

In patients with suspected intracerebral hemorrhage, CT is the most effective initial test to accurately identify the location, site, direction of extension, and type of an acute intracerebral hemorrhage. The presence and degree of hydrocephalus, ventricular shift or compression, and edema can be assessed. While MRI is not used acutely, it becomes an important diagnostic tool later for identifying whether vascular malformations or tumors are present.

Carotid Doppler ultrasonography is used as a noninvasive means of evaluating for stenosis or occlusion of the common and proximal portions of the internal and external carotid arteries. Transcranial Doppler ultrasound is a technique that allows identification of alteration in direction or velocity of flow in the basal intracranial arteries. This test can be helpful in subarachnoid hemorrhage to evaluate for vasospasm.

Angiography is indicated in patients who are possible candidates for carotid endarterectomy with moderate to severe carotid artery stenosis on noninvasive testing or in patients with suspected vasculitis, arterial dissection, or with suspicion of other intracranial vasculopathies. Cerebral angiography plays an important role in the evaluation of selected patients with intracerebral hemorrhage. Angiography is of importance when there is reason to suspect an aneurysm, arteriovenous malformation (AVM), vasculitis, or moyamoya disease. Angiography is performed in patients who have an atypical location for hypertensive hemorrhage or in the young patient without hypertension.

In patients with spinal cord ischemia, a spinal MRI may show an area of infarction or hemorrhage or a vascular malformation.

Fluid and Tissue Analysis. A basic workup that should be performed in all patients with ischemic stroke includes a complete blood count with differential and platelet count, erythrocyte sedimentation rate, prothrombin time with International Normalized Ratio (INR), partial thromboplastin time, plasma glucose level, blood urea nitrogen, serum creatinine, lipid analysis, luetic serology, and urinalysis (see Iab|e.22I3. ).

A basic evaluation that should be performed in all patients with intracerebral hemorrhage includes a complete blood count with differential and platelet count, prothrombin time with partial thromboplastin time, erythrocyte sedimentation rate, plasma glucose, serum alkaline phosphatase, serum glutamic oxalate transaminase, serum calcium, blood urea nitrogen, serum creatinine, and urinalysis. Additional paraclinical evaluation is listedin iTab,!e,„22-3 .

Cerebrospinal Fluid. There is almost no indication for a lumbar puncture in patients suspected of having ischemic stroke or intracerebral hemorrhage. Rarely, patients suspected of having infection as a cause of stroke may need CSF analysis. In patients with intracerebral hemorrhage or a large hemispheric stroke, a lumbar puncture can be dangerous because of sudden intracranial compartmental shifts with resultant herniation. Patients with suspected subarachnoid hemorrhage with a CT scan that does not reveal hemorrhage should undergo a lumbar puncture. There is no need to perform a lumbar puncture if the CT scan shows subarachnoid blood.

Neuropsychological Tests. Depression occurs in 30 to 50 percent of stroke patients within 2 years of the initial event. y Poststroke depression produces physical, emotional, and cognitive symptomatology and may have a major impact on the recovery of these patients. Approximately 40 to 50 percent will display depressive symptomatology in the first month after stroke. About half of the patients meet criteria for major depression. The other half have minor depressive symptoms. A particularly interesting finding, not corroborated by all investigators, has been that depression is most common with strokes involving the frontal lobe and head of the caudate nucleus, particularly with lesions close to the frontal pole. Depression is more common with lesions affecting the left dorsolateral frontal lobe in comparison with the right frontal pole. One possible explanation for this neuroanatomical correlation is that such lesions may interrupt noradrenergic and serotoninergic pathways. Poststroke depression responds to tricyclic antidepressants and selective serotonin reuptake inhibitors. Persuading patients to comply with treatment requires a detailed explanation of the potential unwanted effects of the medications. The selection of the antidepressant is based on the side effect profile of the medication and the clinical characteristics of the patient.

Other neuropsychiatric problems that can occur after stroke include mania, anxiety, bipolar affective disorders, and psychosis. Another problem that can develop is a pseudobulbar affect or emotional incontinence that may be

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TABLE 22-3 --

US

EFUL STUDIES IN THE EVALUATION OF DISORDERS OF NEUROVASCULAR FUNCTION

Syndrome

1 Neuroimaging

Electrophysiology | Fluid and Tissue Analysis | Neuropsychological Tests | Other Tests

ISCHEMIA

ISCHEMIA

Diffuse hypoperfusion

Uni- or bilateral infarcts in watershed" areas

Cerebral Spinal cord

Extracranial steal syndrome

Focal Ischemia Large vessel

Small vessel lacunae

HEMORRHAGE

Subarachnoid

Intracranial hematoma

Infarct in thoracic "watershed" areas

Normal unless infarct occurs

Infarct in involved region

Small infarcts subcortex and brain stem

Blood subarachnoid space, MR angiogram may visualize aneurysm

EEG: diffuse slowing SSEP delay EEG usually normal

Intraparenchymal blood

Polymorphic delta waves over region

Normal

Varying degrees of diffuse slowing

EEG: polymorphic slow waves over region

NA NA NA

Depressed LOC

Normal

Lab tests

Lab tests

CSF: RBC's/xanthochromia

Decreased CSF cystatin C (cerebral amyloid angiopathy)

None None None

Variable depending on site

Variable depending on site

Depressed LOC dependent on extent of bleeding, hydrocephalus, and vasospasm

Variable depressed LOC depending on site

Chest x-ray, ECG, NV tests

Chest x-ray, ECG, NV tests

Cerebral angiography to show aneurysm

Biopsy of hematoma site may reveal tumor cells or cerebral amyloid angiopathy

Extracranial hematomas

Extradural or subdural defects

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