Are somatosensory evoked potentials the best predictor of outcome after severe brain injury? Caution in interpreting a systematic review

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Dear Sir: Carter and Butt’s systematic review of the use of somatosensory evoked potentials (SEP) to predict outcome after severe brain injury [1] and their previous systematic review [2] determined that SEP are a powerful predictor of outcome. However, I wonder whether SEP are best at predicting the outcome of early death as we currently practice intensive care and believe that they are of unknown value in predicting nonrecovery from persistent vegetative state (PVS). The sensitivity of bilaterally absent SEP for unfavorable outcome in the authors’ systematic review is 46.2% [2]. In those with an unfavorable outcome 70% (43%/61%) died [1]. The authors point out the “lack or absence of details on the approach to the withdrawal of treatment...and only two included studies reported the provision of maximal treatment for a predetermined minimal period (3 days)” [2]. Perhaps the majority of patients with SEP-predicted unfavorable outcomes died early, and the proportion of those in PVS with good follow-up was small. …