The principal division in the classification of cerebrovascular insults is between those that result from ischemia and those resulting primarily from blood vessel rupture, causing hemorrhage. Hemorrhagic strokes are divided into various types:
Hemorrhagic strokes share with ischemic processes a more or less sudden onset but cause cerebral damage in different ways:
Within each category, cortical involvement increases the likelihood of seizures. Larger lesions and more severe deficits are associated with a higher risk of seizures and epilepsy in most, but not all, circumstances
Congenital vascular malformations are a common cause of intracerebral hemorrhage, especially in younger people. These are usually divided into three types:
A fourth type of vascular malformation, capillary telangiectasias, consists of dilated capillary structures with intervening neural tissue. These are most often located in the pons and are rarely symptomatic.
Subarachnoid hemorrhage may result from AVMs or from coagulation or platelet defects, but the most common cause by far is rupture of a saccular aneurysm, thought to result from an area of congenital weakness in the arterial wall, usually located at branch points near the circle of Willis. The most common locations of these aneurysms are the junction of the posterior communicating artery and internal carotid artery and the anterior communicating artery. Next most common are the proximal middle cerebral artery and then the posterior circulation.7 Thought to be congenital, they are present in perhaps 5% of the population. The likelihood of rupture increases markedly with advancing age, as well as with hypertension and smoking.
Approximately one-third of ruptures are immediately fatal, another one-third result in significant disability, and another one-third of patients recover without major disability.
The major risks after the initial bleed are
Acute symptomatic seizures may occur at the time of the initial bleed, when they may be confused with syncope resulting from transient cessation of cerebral perfusion, caused by the acute rise in intracranial pressure to equal the systemic pressure. Epilepsy and acute symptomatic seizures may be related to hemorrhages that occur parenchymally, as well as in the subarachnoid space. Intracerebral extension of the hemorrhage is often associated with rupture of aneurysms that involve the anterior communicating artery and damage the orbitofrontal cortex.
Subarachnoid and subdural bleeding can result from another type of anomaly, dural arteriovenous fistulas, which may be acquired as a result of trauma or other insult. These can also cause seizures and epilepsy, but the usual presentation is chronic headache.18
Intracerebral hemorrhages are most commonly due to acute and chronic hypertension. In these patients, most of the hemorrhages are located in the basal ganglia, especially the putamen. Although lobar hemorrhages are more likely to produce seizures and epilepsy, some deep hemorrhages, especially those involving the caudate,19 may also lead to seizures.
A substantial proportion of lobar hemorrhages may in fact be due to a different source of vascular damage than that produced by hypertension. The terms cerebral amyloid angiopathy (CAA), cerebral congophilic angiopathy, and cerebrovascular amyloidosis refer to a clinicopathologic entity characterized by hyaline eosinophilic staining properties.20 CAA is implicated as the cause of primary nontraumatic intracerebral hemorrhage in as many as 10–15% of patients over the age of 60 years and in nearly 20% of patients over the age of 70 years.21 This pathology may also produce seizures in the absence of gross hemorrhage; petechial hemorrhage is suspected.22
Other causes of intracerebral hemorrhage include coagulopathies. These may be congenital, such as the hemophilias, or acquired, often as a result of treatment with anticoagulants or thrombolytic agents.
Reviewed and revised April 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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