A new possible mechanism of hearing loss after microvascular decompression for hemifacial spasm.
OBJECTIVE
Hearing loss is a well-known complication that may occur during microvascular decompression (MVD) for hemifacial spasm (HFS). Cause and risk factors are highly variable. We present cases of hearing loss induced by saline overinfusion after MVD.


METHODS
Retrospective review in a tertiary referral center.


METHODS
Three hundred thirty-one patients with HFS underwent MVD from March 2009 to October 2010.


METHODS
Brain stem auditory evoked potential (BAEP) was monitored during the surgery. Before completion of the dural closure, the surgical field was routinely filled with warm saline to avoid postoperative pneumocephalus and epidural hematoma.


RESULTS
Seven patients experienced a change in wave V amplitude and latency after the dural closure. In 2 patients, the amplitudes decreased by less than 50%, and latencies were delayed by less than 1.0 ms, ipsilaterally in 1 patient and contralaterally in the other. In 1 patient, decreased amplitude and delayed latency appeared bilaterally with more severity on the operated side, accompanied by delayed ipsilateral permanent hearing loss. In 4 of the 7 patients, an ipsilateral response of BAEP was completely absent. Of these 4 patients, 2 experienced permanent hearing loss, and another 2 patients who underwent dural reopening and saline drainage had restoration of their normal hearing.


CONCLUSIONS
Intradural compression due to overinfusion of saline may lead to postoperative hearing loss, although the incidence is low, and immediate decompression by drainage may be required.
Department of Neurosurgery, The Catholic University of Korea College of Medicine, Bucheon St. Mary's Hospital, Bucheon, Republic of Korea. jkw94@naver.com
Kwang Wook
KW
Jo
Jeong Ah
JA
Lee
Kwan
K
Park
Yang Sun
YS
Cho
D000368:Aged; D001301:Audiometry, Pure-Tone; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005154:Facial Nerve / Q000601:surgery; D005260:Female; D034381:Hearing Loss / Q000209:etiology*; D019569:Hemifacial Spasm / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D061145:Microvascular Decompression Surgery / Q000009:adverse effects*; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications / Q000209:etiology*; D013063:Speech Discrimination Tests