- Nonarteriosclerotic causes of stroke occur more commonly in patients admitted to the ICU and should be carefully sought by appropriate diagnostic tests.
- In patients with acute ischemic stroke, reduction of systemic blood pressure may carry a risk of producing further neurologic deterioration.
- Intravenous tissue plasminogen activator improves outcome in carefully selected patients with acute ischemic stroke when treatment is instituted within 3 hours of onset.
- Clinical trials of anticoagulation
with heparin or heparin-like drugs in patients with acute cerebral ischemia or infarction have shown no benefit. If other indications for acute anticoagulation are present, these drugs may be given safely.
- Emergency neurosurgical intervention should be strongly considered in patients with cerebellar infarction or hemorrhage and consequent brain stem compression.
- Early surgical clipping or coiling of ruptured aneurysms removes the risk of rebleeding and facilitates the effective management of delayed vasospasm and hydrocephalus.
Cerebrovascular diseases can be divided into three categories: cerebral ischemia and infarction, intracerebral hemorrhage, and subarachnoid hemorrhage.
Cerebral ischemia and infarction are caused by processes that reduce cerebral blood flow. Reductions in whole brain blood flow due to systemic hypotension or increased intracranial pressure (ICP) may produce infarction in the distal territories or border zones of the major cerebral arteries. More prolonged global reductions cause diffuse hemispheric damage without localizing findings, or at its most severe produce brain death. Prolonged regional reductions can lead to focal brain infarctions. Local arterial vascular disease accounts for approximately 65% to 70% of all ischemic strokes. In most cases, arterial disease serves as a nidus for local thrombus formation with or without subsequent distal embolization. Focal arterial stenosis in combination with systemic hypotension is a rare cause of focal brain infarction. Atherosclerosis is the most common cause of local disease in the large arteries supplying the brain. Disease of smaller penetrating arteries may cause small deep (lacunar) infarcts; it is unclear how often these lacunar infarcts are caused by atherosclerosis, some other arteriosclerotic process of small vessels, or by small emboli arising from more proximal sources. While emboli arising from the heart cause approximately 30% of all cerebral infarcts in a general population, they assume more importance in ICU patients.1 Atrial fibrillation is the most common cause. Atherosclerotic emboli following heart surgery, infective endocarditis, nonbacterial thrombotic endocarditis, and ventricular mural thrombus secondary to acute myocardial infarction or cardiomyopathy should all be considered in appropriate circumstances. Rarer causes of cerebral infarction must also be considered in the ICU. These include dissections of the carotid or vertebral artery after direct neck trauma, “whiplash” injuries or forced hyperextension during endotracheal intubation, intracranial arterial or venous thrombosis secondary to meningeal or parameningeal infections, and paradoxical embolization from venous thrombosis via a patent foramen ovale.1
Hemorrhages into the basal ganglia, thalamus, and cerebellum in middle-aged patients with long-standing hypertension are the most common type of intracerebral hemorrhage. In hypertensive patients with hemispheric lobar hemorrhages and patients without hypertension, other causes should be sought, such ...