Intraoperative neurophysiologic monitoring in 80 patients with Chiari I malformation: role of duraplasty.

Neurophysiologic intraoperative monitoring of the brainstem auditory evoked potentials (BAEPs) is a widely used method to assess the functional integrity of the central auditory system during surgery involving the brainstem or the cranial nerves. The purpose of this study is to describe our experience with neurophysiologic intraoperative monitoring of BAEPs during posterior fossa decompression (PFD) surgery for the management of Chiari I malformation. Although suboccipital craniectomy is the standard surgical technique applied in all cases undergoing PFD, the role of dural patch grafting (duraplasty) remains controversial. In most cases, the PFD was supplemented by duraplasty only when the Chiari I malformation was complicated by the presence of syringomyelia. Our study reviewed the intraoperative BAEP changes during the different surgical stages of Chiari repair and correlated these with clinical and radiological findings present. Our data revealed that for both groups of patients, with or without associated syringomyelia, the predominant improvement in central conduction in most cases occurred during the period of bony decompression without significant additional improvement after the duraplasty procedure.