When monitoring median nerve SSEPs during posterior fossa exploration for tic douloureaux, what will it show?

Monitoring median nerve somatosensory evoked potentials (SSEPs) during posterior fossa exploration for tic douloureux provides valuable information about the integrity of the somatosensory system as it traverses the brainstem structures. In this context, SSEPs are used to assess how sensory signals from the median nerve are processed as they travel through the nervous system, particularly when subject to surgical manipulation in the posterior fossa where relevant anatomical structures reside.

During surgery, any impact on the neural pathways can lead to changes in the SSEPs, indicating whether the somatosensory pathways, including those that traverse the brainstem, remain intact. A consistent response in the SSEPs suggests that the pathways involved in carrying sensory information are functioning correctly, while alterations or losses in the signal could indicate potential nerve damage or interference from surgical instruments.

This monitoring is particularly critical in cases like tic douloureux, where the trigeminal nerve and its root entry zone are relevant. Therefore, while assessing other aspects like the integrity of the brain stem or the location of the trigeminal nerve can be significant, SSEPs are primarily used to evaluate the somatosensory system traversing brainstem structures.