Intraoperative neurophysiological monitoring of microvascular decompression for glossopharyngeal neuralgia.

PURPOSE: To evaluate if adding cranial nerves (CNs) V and VI to standard intraoperative neurophysiological monitoring (IONM) of microvascular decompressions for glossopharyngeal neuralgia improve its efficacy.

METHODS: We reviewed all patients who received a microvascular decompression for glossopharyngeal neuralgia at our institution between January 2008 and August 2012. All received upper extremity somatosensory evoked potentials, brainstem auditory evoked potentials, and free-running electromyography of muscles innervated by ipsilateral CNs VII, IX, and X. The sample was divided into 12 patients who received additional monitoring of CNs V and VI and 15 who did not.

RESULTS: No difference on neurotonic activity presence was found on CN V (standard IONM: 0% versus additional CNs IONM: 8.33%; p = 0.423), CN VI (never present on the additional CN patients), CN VII (standard IONM: 73.33% versus additional CNs IONM: 66.64%; p = 0.973), CN IX (standard IONM: 40.0% versus additional CNs IONM: 25.0%; p = 0.683), or CN X (standard IONM: 46.67% versus additional CNs IONM: 33.33%; p = 0.701) between groups. Additionally, no differences of brainstem auditory evoked potentials wave V's delay, and amplitude at the end of the decompression, or closing of the case were found between groups.

CONCLUSIONS: Monitoring free-running electromyography of additional CNs V and VI does not improve the efficacy of IONM of microvascular decompressions for glossopharyngeal neuralgia.