Distributed, limbic gray matter atrophy in patients after bacterial meningitis

The structural basis of cognitive sequelae after bacterial meningitis in humans is still poorly understood. In animal models and human autopsy cases, neuronal apoptosis of the hippocampal formation in particular seems to play an important role. Here, we aimed to analyze if BM entails MR imaging structural consequences in humans in vivo. We applied voxel-based morphometry in a cohort of BM survivors with normal conventional MR imaging after resolution of the acute inflammation to assess morphologic differences. We found clear gray matter volume loss in the limbic system including the hippocampal formation, thalamus, and cingulate gyri bilaterally as well as in the temporal lobe. These results were corroborated by an alternative atlas-based method. Even in patients with normal routine MR imaging results, clear-cut gray matter atrophy with a mesial temporal/limbic pattern was evident. The anatomic distribution is compatible with the neuropsychological deficit commonly observed in patients after BM. The similarity of the observed atrophy may point to causal link between BM and mesial temporal epilepsy.