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 ac ute, severe brain injury, and to compare this with the predictive powe r 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 p atients had absent SEPs and a favorable outcome by the Glasgow Outcome Scale (full recovery or moderate disability); two of these patients h ad meningitis with bilateral subdural effusions, one had a mid-brain h emorrhage, and one had a decompressive craniectomy for uncontrolled in tracranial hypertension. Normal SEPs had a positive predictive value f or favorable outcome of 93% (95% confidence interval (Cl), 77% to 99%) , and absent SEPs had a positive predictive value for unfavorable outc ome by the Glasgow Outcome Scale (severe disability, survival in a per sistent vegetative state, or death) of 92% (95% Cl, 80% to 98%). If th e above identifiable clinical situations in which a physical barrier e xisted to impede cutaneous reception of the electrical impulse were ex cluded, the positive predictive value of absent SEPs for poor outcome reached 100% (95% Cl, 92% to 100%). An absent motor response to painfu l stimulus also had 100% positive predictive value (95% Cl, 84% to 100 %) for unfavorable outcome; however, 23% of patients could not be eval uated because of the effects of muscle relaxants or sedatives. In pati ents with traumatic brain injury, results of computed tomography did n ot reliably predict outcome. Of the 59 patients with unfavorable outco me, 76% could be identified with SEPs compared with 36% with examinati on of motor function. We suggest that SEPs be performed in children wi th 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 conside ration of withdrawal of treatment in children with brain injuries.