Somatosensory evoked potentials for prediction of outcome in acute severe brain injury

The purpose of this study was to evaluate prospectively short-latency somatosensory evoked potentials (SEPs) as a predictor of outcome in acute, severe brain injury, and to compare this with the predictive power of the motor component of the Glasgow Coma Scale score and computed tomographic scan. Outcome was measured with the Glasgow Outcome Scale at a minimum of 6 months after injury. We studied 109 patients (aged 0.1 to 16.8 years) with SEPs within 4 days of the onset of coma. Four patients had absent SEPs and a favorable outcome by the Glasgow Outcome Scale (full recovery or moderate disability); two of these patients had meningitis with bilateral subdural effusions, one had a midbrain hemorrhage, and one had a decompressive craniectomy for uncontrolled intracranial hypertension. Normal SEPs had a positive predictive value for favorable outcome of 93% (95% confidence interval (CI), 77% to 99%), and absent SEPs had a positive predictive value for unfavorable outcome by the Glasgow Outcome Scale (severe disability, survival in a persistent vegetative state, or death) of 92% (95% CI, 80% to 98%). If the above identifiable clinical situations in which a physical barrier existed to impede cutaneous reception of the electrical impulse were excluded, the positive predictive value of absent SEPs for poor outcome reached 100% (95% CI, 92% to 100%). An absent motor response to painful stimulus also had 100% positive predictive value (95% CI, 84% to 100%) for unfavorable outcome; however, 23% of patients could not be evaluated because of the effects of muscle relaxants or sedatives. In patients with traumatic brain injury, results of computed tomography did not reliably predict outcome. Of the 59 patients with unfavorable outcome, 76% could be identified with SEPs compared with 36% with examination of motor function. We suggest that SEPs be performed in children with acute severe brain injury because they add an important tool to the physician's prognostic armamentarium. We conclude that in the absence of the above mentioned identifiable clinical situations, absent SEPs predict 100% unfavorable outcome, and this finding may warrant consideration of withdrawal of treatment in children with brain injuries.