聴神経腫瘍のTranstemporal Approachによる手術

TOTAL REMOVAL OF ACOUSTIC NEURINOMAS THROUGH TRANSTEMPORAL APPROACH

I．はじめに

　W．F．House, T．　L．　Kurzeらの貢献によりここに数年来聴神経腫瘍の手術法としてtranstemporal approachが開拓されてきた。これはmicrosurgical techniqueを用いて特に損傷されやすい顔面神経を保存し，また聴神経腫瘍の内耳道内部分をも摘除しようということに主眼をおいたものであるが，このtranstemporal approachと従来のsuboccipital approachの比較をめぐつて論議がかわされている。われわれも最近聴神経腫瘍の2症例にtranstemporal approachによる手術を試み，いずれも全摘除に成功した。1例はごく初期の聴神経腫瘍で腫瘍は内耳道内に限局していたのでmiddle fossa extradural approachにより内耳道を開放し，腫瘍の全摘を行なつた。他の1例はすでに内耳道外に発育していたのでtranslabyrinthine approachにより腫瘍の内耳道内部分を含めて完全に摘除することができた。ここにその症例を報告するとともに，この問題について多少の考察を加えてみることにした。最初症例について述べてみよう。

In recent years, the transtemporal approach for acous-tic neurinoma has stimulated the interest of neurosur-geons and otologists.

We have succeeded total removal of acoustic neu-rinoma in two cases through the transtemporal ap-proach.

Case 1, 33 year-old man. He developed occipital headache with nausea one year prior to surgery. He had also some unsteadiness. About six months later, progressive hearing loss and tinnitus on the left side began and twitching over the left side of the face was noticed. Neurological findings were normal except for signs referable to the seventh and eighth cranial nerve dysfunction. On x-ray examination, only a slight enlargement of the internal auditory canal was revealed. Operation was performed through middle fossa extradural approach. A pea-sized neurinoma was found to be localized within the internal auditory canal. The tumor did not extend into the cerebellopontine angle and total removal of the tumor was possible. But preservation of the facial nerve was failed.Postoperative course was uneventful.

Case 2, 41 year-old man noticed tinnitus in the both ears one year before the operation. Four months later, hearing loss on the left and unsteadiness on gait developed. He also complained of a heaviness of the head, numbness in the left half of the tongue and changes in taste. Neurological findings were that of the typical acoustic neurinoma with involvement of the fifth and seventh cranial nerve and the cerebellum. Operation was performed through translabyrinthine approach. It was a sparrow-egg sized tumor and total removal was done successfully. On the third postop-erative day, cerebrospinal fluid leakage through the retroauricular wound developed. Therefore, operation wound was reopened and the dural defect was care-fully closed. The mastoid cavity was obliterated with a temporal muscle flap.

Transtemporal approach using microsurgical tech-niques was accomplished by W. F. House. He claims that acoustic neurinoma can be removed with low mortality, preserving the facial nerve and the anterior inferior cerebellar artery. His method is said to pro-vide an excellent approach to the intracanalicular le-sions.

We have described the detail of middle fossa extradu-ral approach, translabyrinthine approach (by House), and posterior fossa transmeatal microdissection (by Kurze). Advantages and disadvantages of, and indi-cations for each of these approaches were also dis-cussed.