Trauma to the pontomesencephalic brainstem--a major clue to the prognosis of severe traumatic brain injury

Abstract

The objective of this study was to assess the significance of an injury to the pontomesencephalic brainstem in severe traumatic brain injury [Glasgow coma score (GCS) below 8]. Forty victims of severe traumatic brain injury with and with out compounding pathologies almost equally distributed among both groups were studied. The outcome (mean follow-up, 11.3 months) was assessed by means of the Glasgow outcome score (GOS) and of the Disability rating scale (DRS). Injury of the brainstem was detected by electrophysiological investigation (evoked potentials, brainstem reflexes) and magnetic resonance imaging (MRI) carried out early after trauma. Statistical analysis (Wilcoxon signed rank test for matched pairs) revealed a significantly worse initial GCS (median 5 versus 6), GOS (median 3 versus 4), and DRS score (median 6 versus 2) for the group with brainstem lesions than for the group without such lesions. Moreover, there was a significant accumulation of lesions of the corpus callosum, the basal ganglia, and the (para-)hippocampal area detected by MRI in the brainstem lesion group. In addition, the finding of an abnormal cortical component of the median nerve evoked somatosensory potential was significantly more frequent in the patients with brainstem injury. Traumatic brainstem lesions diagnosed by MRI a nd/or electrophysiological investigation are associated with injury to other 'deeply' situated parts ofthe brain. The finding of a brainstem lesion influences to the outcome of patients after severe traumatic brain injury.