Valuableness of introduction of laryngeal abductor reflex intraoperative neuromonitoring technique in lower brainstem lesion.

Background: Our aim is to evaluate the use of laryngeal adductor reflex (LAR) for posterior fossa and brainstem surgeries in conjunction with current intraoperative neuromonitoring (IONM) techniques.

Case Description: The patient is a 62-year-old woman who complained of decreased hearing on her left side, dizziness, and left facial palsy. After proper investigation, she was found to have a left vestibular schwannoma. She was scheduled for the left retrosigmoid approach and electrodes embedded on the surface of the endotracheal tube were inserted to monitor for LAR. Preoperative baseline monitoring was recorded. During intraoperative resection of tumor, a significant bilateral amplitude response decrease of the LAR was noted, along with left side decrease in vocal muscle motor evoked potential amplitude responses and bradycardia. Following the LAR event, owed to numerous other IONM changes, surgery was terminated to avoid any complications.

Conclusion: LAR is an integral tool to constantly monitor vagus nerve function that can be used in combination with other IONM modalities during lower brainstem and posterior fossa surgeries. We advocate the IONM use of LAR in brainstem surgeries.