Review: absence of somatosensory evoked potentials after onset of coma has a high specificity for predicting nonawakening.

S t u d y s e l e c t i o n Studies were selected if they were published in English; assessed the association between SEPs (initial cortical responses from median nerve stimulation—i.e., the N19 or N20 responses) and awakening from coma; and reported coma cause, age group studied, presence or absence of SEP responses, timing of SEPs, and coma outcomes. Study exclusion criteria included single case reports, case series with < 4 patients, and articles from non–peer-reviewed journals.