The dynamics of neuronal dysfunction and recovery following severe head injury assessed with serial multimodality evoked potentials

Abstract

Serial studies of visual, auditory, and somatosensory evoked potentials (EP's) obtained from 139 severely head-injured patients up to 1 year after trauma were analyzed to ascertain whether or nor EP's can be used to monitor neurological recovery or deterioration following secondary insults. The EP data were analyzed using a grading system of abnormality developed previously, and patients were grouped by the most severe EP abnormality found in any modality during an early study (mean Day 3). The findings showed differential recovery trends depending on the severity of EP abnormality obtained on the initial study and presence of secondary insult. If EP's were normal early after injury, they remained so for up to 1 year, and these patients did well clinically. The EP's that were absent did not improve, and the patients had poor outcomes. Secondary insults did not affect the EP's or the outcomes of patients in these two groups. When EP's that were initially mildly abnormal became normal or remained no worse than mildly abnormal, patients had favorable outcomes in spite of complications. In contrast, deterioration of EP's with secondary insult indicated poor patient outcome. Severe EP abnormalities which improved over time led to favorable outcomes. However, persistence or deterioration of severe abnormalities indicated a poor outcome. Changes in EP's over time were better indicators of outcome than the presence or absence of complications. The results suggest that EP's may be used to assess neural recovery and the consequences of secondary insults to the brain. Four case reports are included to exemplify results.