The Added Value of Somatosensory Potential N70 in Neurological Prognosis After Coma by Acute Brain Structural Injury: A Retrospective Study

Abstract

Background: Coma after acute brain structural injury (ABI) are associated with high mortality and disability. Somatosensory evoked potentials (SSEP) N20 and N70 are used to predict prognosis. Purpose: We assessed the utility of SSEP (N20-N70) as an early indicator of long-term functional prognosis in these patients. Methods: We conducted a retrospective cohort study of patients admitted to the intensive care unit (ICU) with a diagnosis of coma after ABI (n=60). An SSEP study including N20 and N70 was performed 24–72 hours after coma onset. Functional recovery was evaluated 6 to 12 months later using the Modified Glasgow Scale (mGS). The study was approved by our local research ethics committee. Results: The absence of N20 (41% specificity=100%) or N70 (78%) was a strong indicator of a poor outcome. In contrast, the presence of N70 was an indicator of a good outcome (specificity=64.2% sensitivity=91.3%). Conclusion: SSEP N20 and N70 are useful early prognostic markers with high specificity (N20) and sensitivity (N70). N70 has potential additional value for improving the prediction of good functional outcomes in the long term.