Preservation of the saccular nerve and of the vestibular evoked myogenic potential during vestibular schwannoma surgery.
OBJECTIVE
The aim of the study was to present a case report demonstrating that vestibular evoked myogenic potentials originate from the saccular nerve.


METHODS
Retrospective case review.


METHODS
Tertiary referral center.


METHODS
Vestibular evoked myogenic potentials are shown before and after operation in a patient with a surgically confirmed superior vestibular schwannoma (1.3 cm).


METHODS
Preoperative and postoperative audiometry, auditory brainstem response, caloric test, vestibular evoked myogenic potentials, and magnetic resonance imaging outcomes. RESULTS On preoperative audiometry, slight sensorineural hearing loss with normal auditory brainstem response could be detected. Caloric tests showed a reduced response of the right labyrinth. Vestibular evoked myogenic potentials were normal. The tumor was removed via a combined retrosigmoid and partial labyrinthectomy approach with the removal of the posterior semicircular canal. The facial, auditory, and inferior semicircular nerves were anatomically preserved. Postoperative audiometry revealed preservation of hearing and vestibular evoked myogenic potentials; caloric responses were now absent.


CONCLUSIONS
The combined retrosigmoid and partial labyrinthectomy approach represents an ideal condition to study the influence of the saccular nerve on the origin of the vestibular evoked myogenic potentials. The maintenance of the vestibular evoked myogenic potential responses in our patient supports the concept that the vestibular evoked myogenic potential originates in the saccule and is transmitted in the saccular nerve.
Magliulo
Giuseppe
G
ENT Department, University La Sapienza, Rome, Italy. giuseppemagliuloorl@yahoo.com
Gagliardi
Mario
M
Ciniglio Appiani
Giuseppe
G
D'Amico
Raffaello
R
D001301:Audiometry, Pure-Tone; D002150:Caloric Tests; D003391:Cranial Nerves / Q000502:physiology*; D007758:Ear, Inner / Q000601:surgery; D005071:Evoked Potentials / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D009464:Neuroma, Acoustic / Q000150:complications / Q000473:pathology / Q000601:surgery*; D013506:Otologic Surgical Procedures / Q000379:methods; D011182:Postoperative Care; D011300:Preoperative Care; D012189:Retrospective Studies; D012444:Saccule and Utricle / Q000294:innervation*; D014722:Vestibule, Labyrinth / Q000502:physiology*