Operative Strategies for Minimizing Hearing Loss and Other Major Complications Associated with Microvascular Decompression for Trigeminal Neuralgia Aaron E. Bond 1 , Gabriel Zada 1 , Andres A. Gonzalez 2 , Chris Hansen 2 , Steven L. Giannotta 1 INTRODUCTION Vascular compression of the trigeminal nerve causing trigeminal neuralgia (TGN, tic douloureux) was first reported by Dandy in 1932 (12). Since the initial description, several modalities for the treatment of TGN have evolved, including medical ther- apy, stereotactic radiosurgery, glycerol rhi- zotomy, radiofrequency thermal rhizotomy, balloon microcompression, and surgical microvascular decompression (3). Micro- vascular decompression (MVD) is com- monly relied upon as the definitive nonab- lative treatment of refractory TGN, with a reported success rate of 63%–94% (1, 2, 5-8, 11, 17-19, 21, 24, 25, 27, 29, 30, 32, 35) and a reported major complication rate of 1.2%–5.2% (2-4, 6, 7). A relatively infrequent yet significant risk of the MVD procedure is permanent hear- ing impairment associated with damage to the vestibulocochlear nerve (CN VIII), which typically occurs as a result of exces- sive retraction of the cerebellum performed in order to expose the trigeminal cistern. Less frequently, hearing loss occurs as a re- sult of direct trauma to the cranial nerve complex or its vascular supply. Earlier MVD procedures that did not utilize more mod- ern operative techniques or brain stem au- ditory evoked potential monitoring (BAEP) resulted in relatively higher rates of hearing loss ranging from 2% to 19% (5, 8, 9, 18, 19, 23, 26, 31, 34). With the introduction of BAEP and refined exposure techniques, however, more emphasis has been placed on minimizing traction on cranial nerve (CN) VIII, and rates of postoperative hear- ing loss have been reduced to less than 2% in modern series (2, 5, 8, 17, 20, 27, 28). In the current report, the records of 119 pa- tients undergoing MVD for TGN by the se-  OBJECTIVE: To retrospectively assess the surgical outcomes and complica- tion rates following microvascular decompression (MVD) for trigeminal neural- gia, using a targeted, restricted retrosigmoid approach.  METHODS: During the period 1994-2009, a total of 119 patients underwent MVD for trigeminal neuralgia. A retrospective review was conducted in order to assess pain outcomes following surgery and at most recent follow-up. The intraoperative findings, Barrow Neurologic Institute (BNI) pain scores, medication usage, brainstem auditory evoked potential records, and compli- cation rates (including postoperative hearing status) were reviewed and subsequently analyzed.  RESULTS: Of the 119 patients who underwent MVD, 61 (51%) were male and 58 (49%) were female. The mean age was 60 years (range 22-86 years). Operative findings included 94 patients (79%) with arterial compression, 16 patients (13%) with isolated venous compression, 1 patient (1%) with a small arteriovenous malformation, and 8 patients (7%) with no obvious source of compression. No perioperative deaths or major complications, including hearing loss, occurred in any patients. Minor complications occurred in 9 patients (8%), including a transient trochlear nerve palsy in 1 patient, transient nystagmus in 1 patient, cerebrospinal fluid leak requiring revision in 1 patient, wound infections requiring revision in 3 patients, and wound infections requiring antibiotics alone in 3 patients. Follow-up data were available for 109 patients, of whom 88 (81%) had excellent outcomes (BNI Score I–II). Ninety-eight patients (90%) had good outcomes (BNI scores I–IIIb), 7 patients (6%) had persistent pain that was not controlled with medications (BNI Score IV), and 4 patients (4%) experienced no relief following surgery (BNI Score V).  CONCLUSION: The use of a small craniectomy (<20 mm) in conjunction with a restricted retrosigmoid approach, inferolateral cerebellar retraction, and maintenance of the vestibular nerve arachnoid may minimize complications and optimize surgical outcomes associated with microvascular decompression for trigeminal neuralgia. Key words  Brainstem auditory evoked potentials  Hearing  Intraoperative monitoring  Operative procedures  Tic douloureux  Trigeminal neuralgia Abbreviations and Acronyms BAEP: Brainstem auditory evoked potential BNI: Barrow Neurological Institute CN: Cranial nerve CSF: Cerebral spinal fluid EMG: Electromyography MVD: Microvascular decompression TGN: Trigeminal neuralgia From the Departments of 1 Neurosurgery and 2 Neurology, Keck School of Medicine, University of Southern California, Los Angeles, USA To whom correspondence should be addressed: Steven L. Giannotta, M.D. [E-mail: giannott@usc.edu] Citation: World Neurosurg. (2010) 74, 1:172-177. DOI: 10.1016/j.wneu.2010.05.001 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2010 Elsevier Inc. All rights reserved. PEER-REVIEW REPORTS 172 www.SCIENCEDIRECT.com WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.05.001