Neural connection between injured cingulum and pedunculopontine nucleus in a patient with traumatic brain injury.

We report on a patient with traumatic brain injury who showed neural connection between injured cingulum and pedunculopontine nucleus on diffusion tensor tractography (DTT). A 74-year-old male who had suffered a traffic accident underwent conservative management for subarachnoid haemorrhage. Brain MRI which was performed 6 months after onset showed no specific lesions. On 6-month DTTs for cingulum of the patient, we observed discontinuations of both cingulums above the genu of corpus callosum. However, the left cingulum was connected to the left PPN via a neural tract that passed through the anterior corona radiata and thalamus. The neural connection between the injured cingulum and PPN seems to be a compensatory phenomenon for the destruction of cholinergic pathways from basal forebrain. We believe that this result might suggest one of recovery mechanisms of injured cingulum following brain injury.