Aviation, Space, and Environmental Medicine x Vol. 82, No. 2 x February 2011 137 CASE REPORT W AND O, G ROSSMAN A, A SSA A, T AL D, S HUPAK A. Medical waiver for flying after microvascular decompression for hemifacial spasm. Aviat Space Environ Med 2011; 82:137–9. Background: Microvascular decompression has become the treat- ment of choice for hemifacial spasm. Post-surgical symptoms of vestibu- lar dysfunction may appear, but are mostly transient. The unique occupational demands of military aviators necessitate complete otoneu- rological evaluation after vestibular insults to allow safe return to flying duties. Case Report: We present a case of a military jet-fighter pilot who developed transient vertigo and disequilibrium after microvascular de- compression for hemifacial spasm. Resolution of symptoms and com- plete recovery as documented by vestibular bedside and laboratory tests allowed us to grant the pilot full solo flying privileges. Keywords: vestibular dysfunction, aviation, military, flight, vertigo, MVD, HFS. H EMIFACIAL SPASM (HFS) is an uncommon syn- drome which consists of involuntary bursts of tonic and clonic unilateral contractions of the facial muscles. The average prevalence of HFS in the general population is around 10 per 100,000 (1). The syndrome is caused by chronic irritation of the facial nerve or its nucleus, usu- ally secondary to compression by intracranial arterial blood vessels at the root exit zone of cranial nerve VII (4). The arteries which are most frequently involved are the anterior inferior cerebellar artery (AICA) (34%), the vertebral/basilar artery (22%), and the posterior inferior cerebellar artery (18%) (3). HFS can be relieved by mi- crovascular decompression (MVD), a surgical procedure in which the vascular pressure on the nerve is alleviated. MVD is considered a safe and efficient procedure, and has become the treatment of choice for HFS. Deafness is the main postoperative complication, appearing in up to 8.3%, with permanent hearing impairment observed in 2.3–2.8% of patients (2,8,11). Transient post-procedural vertigo with spontaneous recovery is reported in 7.7– 9.6% of patients having MVD for HFS (8,10). Vestibular dysfunction is of special concern in avia- tors. Subtle vestibular deficits that are asymptomatic under terrestrial conditions may lead to significant spa- tial disorientation during a flight with grave outcome to flight safety. Hence, meticulous assessment of the ves- tibular system is required after vestibular insults before a medical waiver is granted. CASE STUDY A 43-yr-old military jet-fighter pilot had undergone MVD to treat HFS. Past medical history included mild bronchial asthma, which has been inactive for several years, and left peripheral facial nerve palsy, which re- solved spontaneously with residual mild facial asym- metry 10 yr before the development of HFS. Moderate bilateral high tone sensorineural hearing loss (45 dB at 4000 Hz) was known and stable for several years, probably secondary to acoustic trauma. The pilot be- gan to suffer from muscular contractions around the left eye, which progressed to involve all ipsilateral fa- cial muscles toward the neck and was diagnosed with typical HFS (3). Involuntary muscular contractions had gradually increased in frequency and intensity, severely affecting his quality of life, including inter- ference with sleep. Treatment with local injections of Botulinum toxin was of benefit for 4 yr, followed by decreased efficacy, and no apparent effect during the 6 mo before surgery. Magnetic resonance angiography demonstrated com- pression of the pons by the vertebral artery on the left and proximity of the AICA to the VII and VIII cranial nerve bundles ( Fig. 1). The pilot had undergone MVD via the left suboccipital approach under continuous fa- cial nerve monitoring. A large AICA was found under the complex of VII and VIII cranial nerves and was sep- arated from the nerves, albeit without disappearance of pathological conduction on the monitor. Further dissec- tion identified an AICA vascular loop between the facial nerve and an anterior vertebral artery. The artery was separated from the facial nerve and a Teflon sheath was inserted between the nerve and the artery. A short course of corticosteroids was given and the postoperative course was uneventful. Immediate complete relief of HFS was noted, but the pilot suffered from vertigo for 10 d, followed by disequilibrium, which resolved after a From the Israeli Air Force Aeromedical Center, Tel Hashomer; the Israel Naval Medical Institute, Haifa; and the Unit of Otoneurology, Lin Medical Center, The Bruce Rappaport Faculty of Medicine, Tech- nion, Haifa, Israel. This manuscript was received for review in September 2010. It was accepted for publication in November 2010. Address correspondence and reprint requests to: Dr. Ori Wand, flight physician, Israeli Air Force Aeromedical Center, Tel Hashomer, Israel; oriwand@hotmail.com. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/ASEM.2943.2011 Medical Waiver for Flying After Microvascular Decompression for Hemifacial Spasm Ori Wand, Alon Grossman, Amit Assa, Dror Tal, and Avi Shupak