Theoretical Foundations and Results of Mvd

Tinnitus is the hearing of sound mostly within one’s ears or sometimes within one’s head, without external acoustic stimulus. Tinnitus is a common symptom, which can often be easily cured through medication, noise masking, or psychotherapy, but 10% of cases are considered intractable, causing patients to suffer from insomnia, interference with concentration, and hearing disturbance. If left uncured, tinnitus may cause hearing loss, so efforts should be made for its treatment using methods such as medication, sound generators, hearing aids, local anesthesia, local steroid injection, and psychological therapy. Still, some cases are diagnosed as intractable tinnitus, in which case doctors often give up its treatment. Some cases of intractable tinnitus are caused by compression on auditory nerves by the artery at the brainstem root entry zone of the nerve, in which case microvascular decompression (MVD) is often used as a treatment [1-3]. However, the effects of MVD on intractable tinnitus have been reported to be less extensive than on hemifacial spasm or trigeminal neuralgia. No clear criteria have yet been established for surgical treatment of intractable tinnitus [3]. Moreover, the operation involves direct maneuver of the auditory nerves, increasing the chance of postsurgical hypofunction of the nerves. Thus, more advanced microsurgical instrumentation and consistent intraoperative monitoring of the brainstem auditory evoked potential (BAEP) have been introduced to significantly reduce the chance of hearing loss [4,5].