Body temperature in acute stroke: relation to stroke severity, infarct size, mortality, and outcome

In laboratory animals, cerebral ischaemia is worsened by hyperthermia and improved by hypothermia. Whether these observations apply to human beings with stroke is unknown. We therefore examined the relation between body temperature on admission with acute stroke and various indices of stroke severity and outcome.

In a prospective and consecutive study 390 stroke patients were admitted to hospital within 6 h after stroke (median 2.4 h). We determined body temperature on admission, initial stroke severity, infarct size, mortality, and outcome in survivors. Stroke severity was measured on admission, weekly, and at discharge on the Scandinavian Stroke Scale (SSS). Infarct size was determined by computed tomography. Multiple logistic and linear regression outcome analyses included relevant confounders and potential predictors such as age, gender, stroke severity on admission, body temperature, infections, leucocytosis, diabetes, hypertension, atrial fibrillation, ischaemic heart disease, smoking previous stroke, and comorbidity.

Mortality was lower and outcome better in patients with mild hypothermia on admission; both were worse in patients with hyperthermia. Body temperature was independently related to initial stroke severity (p < 0.009), infarct size (p < 0.0001), mortality (p < 0.02), and outcome in survivors (SSS at discharge) (p < 0.003). For each 1 degrees C increase in body temperature the relative risk of poor outcome (death or SSS score on discharge < 30 points) rose by 2.2 (95% CI 1.4-3.5) (p < 0.002).

We have shown that, in acute human stroke, an association exists between body temperature and initial stroke severity, infarct size, mortality, and outcome. Only intervention trials of hypothermic treatment can prove whether this relation is causal.