Management Of Cerebral Edema Associated With Ischemic Stroke

There are three types of ischemic strokes that are more commonly associated with an increased risk of morbidity and mortality: moderate-to-large cerebellar strokes, large cerebral hemispheric strokes, and moderate-to-large strokes in the middle cranial fossa, where a theoretical compartment exists that may lead to early herniation if untreated. Kasner et al.45 evaluated 201 patients with large MCA strokes, and found several factors to be associated with the development of malignant or fatal brain edema. In a multivariable analysis, these factors included a history of hypertension (OR 3.0) or CHF (OR 2.1), increased white blood cell (WBC) count at admission (OR 1.08 per 1000 WBC/pL), hypodensity on computed tomography (CT) scan involving >50% of the MCA territory (OR 6.3) and involvement of additional vascular territories (anterior cerebral artery, posterior cerebral artery, or anterior choroidal artery, OR 3.3). In a bivariable analysis, initial level of consciousness, National Institutes of Health Stroke Scale (NIHSS) score, early nausea and vomiting, and elevated serum glucose were also associated with fatal brain edema. An analysis of 24 complete MCA infarcts by Maramattom et al.46 found a higher rate of malignant edema in female patients (72% vs. 20%) and those with additional territories of infarction (72% vs. 0%) (Fig.8.1).

Qureshi et al.47 evaluated the timing of deterioration in patients with massive MCA strokes in a multicenter retrospective chart review. They found that 68% of patients manifested clinical deterioration by 48 hours, and nearly another 20% did so by 72 hours. Thus, the first 3-5 days appears to be the most crucial time for detecting patients at high risk for deterioration, although there was a small minority of patients who had deterioration at greater than 5 days from symptom onset. Early impairment in consciousness was also found to be predictive of mortality in one cohort of patients within a randomized clinical trial.48 One postmortem study of 192 patients found features in 45 patients that they postulate led to "malignant"

FIGURE 8.1 Massive middle cerebral artery infarction.

infarction.49 These included larger volumes of infarction (including areas in addition to the MCA territory), hemorrhagic transformation, Duret hemorrhages, carotid occlusion, and ipsilateral abnormalities of the circle of Willis (p < 0.5). In a multivariable analysis, younger age, female sex, absence of stroke history, higher heart rate, carotid artery occlusion, and an abnormal ipsilateral circle of Willis all also correlated with malignant infarction (p < 0.3). CT features have been evaluated in a retrospective analysis of 135 patients from seven centers, and in a multivariable analysis the features associated with poor outcome included an anteroseptal shift of >5 mm and infarction beyond the MCA territory.50

Another important factor to consider is the patient's age. Younger patients are at higher risk of early neurological deterioration from cerebral edema associated with strokes, as they have less overall brain atrophy, and thus less tolerance for swelling within the cranial vault. Older patients, however, are more susceptible to poor outcomes, as clinicians may be less likely to be aggressive in their management, excluding them from potentially life-saving procedures. This may lead to a self-fulfilling prophesy for poor outcome in older aged patients. Older patients who do survive massive cerebral infarctions also have been shown to have less rehabilitation capacity, likely secondary to decreased "neuroplasticity" in the older brain.

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