Acute Hiccups Detected by Electromyographic Recordings During Resection of a Vestibular Schwannoma.

BACKGROUND AND

IMPORTANCE

Intraoperative neuromonitoring (IONM) is routinely used to monitor cranial nerve function during resection of vestibular schwannomas. Sudden movements in the surgical field can be a disturbing factor for the surgeon. IONM can help determine the cause of unexpected patient movements.

CLINICAL PRESENTATION: We report the case of a 54-year-old patient who underwent retromastoid craniotomy and resection of a vestibular schwannoma. Toward the end of dissection of the tumor from the lower cranial nerves and brainstem, the patient showed repetitive shoulder elevation. Electroencephalography showed burst suppression, confirming deep sedation and excluding voluntary movements. Free-running electromyography recorded spontaneous, simultaneous, bilateral vocal cord activity that was synchronous with upper body movement. There was simultaneous but smaller activity in the right genioglossus muscle and levator veli palatini, indicative for far-field activity. These IONM findings allowed us to classify the clinical observations as intraoperative hiccups.

CONCLUSION

Hiccups during general anesthesia are rare but should be considered as a differential diagnosis of sudden upper body movement. To the best of our knowledge, this is the first reported case of acute hiccups during resection of a vestibular schwannoma. IONM reliably distinguished it from an increase in intraoperative consciousness or accessory nerve activation resulting in shoulder movements.