1. Home>
2. Specialties>
3. Neurology>
4. Summary and Comment

Predictors and Impact of Fever After Subarachnoid Hemorrhage

Fever is associated with morbidity and mortality after subarachnoid hemorrhage, but a cause-effect association has yet to be established.

To determine predictors of treatment-refractory fever and the relation between refractory fever and clinical outcome in patients with aneurysmal subarachnoid hemorrhage (SAH), researchers analyzed data from 353 patients with SAH culled from a single-center, prospective database of consecutive SAH patients.

The authors defined refractory fever as a temperature elevation above 37°C (normal body temperature) despite treatment with acetaminophen and, when necessary, an external surface cooling device. They recorded at least seven daily-maximum temperatures for each patient. Admission predictors of refractory fever included high clinical grade (Hunt-Hess score, 3–5), presence of intraventricular blood, high radiographic grade (SAH sum score, 15), aneurysm size 10 mm, and initial loss of consciousness. After controlling for these factors, eight complications were significantly associated with refractory fever: brainstem herniation, symptomatic vasospasm, treated hydrocephalus, cerebral infarction, pneumonia, respiratory failure, anemia, and hyperglycemia. For every 1°C above 37°C in mean daily-maximum temperature, the odds increased roughly 9-fold for death, 3-fold for death or moderate-to-severe disability, 2.5-fold for dependence in activities of daily living, and 2.5-fold for cognitive impairment. For every 1°C above 38.3°C (conventional definition of fever), the odds for poor outcomes increased even further (22-fold, 7-fold, 9-fold, and 7-fold, respectively). Most patients (72%) developed at least one temperature elevation of greater than 38.3°C.

Comment: Fever is associated with exacerbation of ischemic brain injury and has therefore become a major focus of neurocritical care. This study demonstrates several important points. First, fever occurs in most patients with subarachnoid hemorrhage. Second, many of the predictors of fever relate to brain injury, and not to infection, underscoring the importance and prevalence of central neurogenic fever. Third, there is a dramatic association between fever and poor clinical outcome, perhaps in a dose-dependent fashion.

Whether fever causes neurologic deterioration or is merely a marker of neurologic injury remains unknown. In the absence of definitive answers, most neurointensivists and stroke neurologists treat fever aggressively. However, the therapeutic modalities currently available are not without risk. External surface cooling devices are associated with patient discomfort and skin breakdown. Endovascular cooling devices are invasive and are associated with an increased incidence of deep vein thromboses. Both methods may cause rigors, which in theory may exacerbate brain injury. Medications used to control rigors and to promote tolerance of cooling have adverse effects as well. A randomized controlled trial designed to establish the relation between induced normothermia and long-term clinical outcomes might provide answers.

— Joshua M. Levine, MD

Dr. Levine is Assistant Professor of Neurology, Hospital of the University of Pennsylvania, Philadelphia.

Published in Journal Watch Neurology July 10, 2007

Citation(s):

Fernandez A et al. Fever after subarachnoid hemorrhage: Risk factors and impact on outcome. Neurology 2007 Mar 27; 68:1013-9.

• Original article (Subscription may be required)
• Medline abstract (Free)