Do somatosensory evoked potentials in traumatic brain injury patients indicate brainstem generators for frontally recorded N18, P20 and cervical N13?

Abstract

Primary objective: To examine the generator of frontal somatosensory evoked potentials by studying patients with traumatic brain injury in the chronic phase.

Research design: A prospective, non-comparative case series.

Methods and procedures: Median nerve somatosensory evoked potentials were performed in 26 survivors of severe traumatic brain injury, which had taken place at a mean of 7 months before. Potentials of short latency somatosensory evoked potentials were recorded simultaneously over the frontal and parietal scalp.

Main outcomes and results: Frontally recorded latencies N18, P20 and N13 recorded from C2 correlated highly significantly with the duration of coma (p<0.01), a history of raised intracranial pressure (p<0.05) and with each other (p<0.01) in traumatic brain injury patients.

Conclusions: These findings indicate that frontally recorded N18, P20 and N13 recorded from C2 are generated in part in the brainstem, which becomes damaged by increased intracranial pressure due to secondary injury in severe traumatic brain injury.