顔面痙攣を合併し神経血管減圧術により治癒し得た耳鳴症例

抄録

Hemifacial spasm (HFS) is a condition caused by vascular compression (s) of the facial nerve. Althoughspasm of the stapedial muscle causes tinnitus in about one third of patients with HFS, accompanying tinnitusdue to neurovascular compression (NVC) is rare. Here we report a patient with intractable tinnitus due toNVC of the acoustic nerve. A 57-year-old man presented with a 10-year history of right HFS. He had sufferedfrom high-pitched continuous debilitating tinnitus in the right ear for the last several months, duringwhich the HFS had also worsened. The tinnitus had interfered with his reading and other daily activities.The patient had been receiving medication for hypertension for several years, but was otherwise healthy.An audiogram showed an average hearing level of 14dB on both sides. Thin-slice high-resolution T2-weightedMR images or CISS (Fourier transformation-constructive interference in steady state) images showedarterial compression of the facial nerve and another blood vessel crossing the acoustic nerve. Microvasculardecompression surgery for HFS and exploration of the acoustic nerve were performed simultaneously. Aposterior approach to the right cerebellopontine angle revealed a branch of the anterior inferior cerebellarartery (AICA) compressing the facial nerve root exit zone caudally. Another branch of the AICA compressedthe acoustic nerve laterally, creating a severe indentation. Both AICA branches were transposedaway from the nerves using a Teflon (R) sling and Gelfoam (R). Immediately after surgery, the HFS andtinnitus disappeared, and an audiogram taken 5 days postoperatively showed no significant hearing loss.Thin-slice T2-weighted MR images are useful for diagnosing cases of NVC and for guiding the surgicalapproach, although diagnosis of NVC for isolated tinnitus would be difficult by MRI alone because of thereportedly high incidence of false-positive findings. If preoperative high-resolution MR images suggest thepresence of NVC in patients with intractable tinnitus accompanying HFS, intraoperative attempts to identifyand transpose the offending vessels should be considered.