Evoked potentials in acute head injured patients with MRI-detected intracerebral lesions

Background. Magnetic resonance imaging (MRI) allows precise detection of in tracranial lesions in head injured patients. We compared intracranial lesio ns detected in MRI to somatosensory evoked potentials (SEP) and brainstem a uditory evoked potentials (BAEP) concerning their prognostic value. Methods. Thirty patients with traumatic brain injury and prolonged recovery were studied. Size, side and number of 474 intra-and extraparenchymal lesi ons as well as lesion localisation based on a specific anatomical classific ation were entered into a database (a total of 7080 data). In addition, we recorded median-nerve SEP (M-SEP), tibial nerve SEP (T-SEP) and BAEP in all of the patients. Findings. M-SEP and Glasgow-Outcome-Score (GOS) one year after injury corre lated significantly to patients with lesions in the brainstem (p < 0.0001) and corpus callosum (p < 0.001). Similar results were found for T-SEP (p < 0.0001). All patients with bicortical loss of M-SEP had an unfavourable out come (GOS 2). Among the analysis of lesion volume, only the volume of brain stem lesions correlated to GOS (p < 0.001), but this was not found for call osal lesions. However, comparing the vegetative (GOS 2) to the nonvegetativ e group (GOS 3-5), for both callosal (p <less than> 0.02) and brainstem (p < 0.005) lesions a significant correlation was found. Interpretation. MRI does not improve the prognostic reliability of SEP in h ead injury but offers possibilities for clarifying electrophysiological and clinical pathologies. This explains that the volume of brainstem lesions, essentially influencing the clinical outcome, is strongly correlated to T-S EP and M-SEP. In contrast, callosal lesions did not show a clear relationsh ip to outcome despite large callosal lesions (> 4 ml) which tended to poor outcome. In conclusion, we suggest that MRI and SEP are supplementary to ea ch other concerning prognostic evaluation.