髄液漏を伴つた側頭骨内髄膜脳瘤（meningoencephalocele）について

MENINGOENCEPHALOCELE THAT PROTRUDED INTO THE MASTOID

　脳実質が硬膜を被つた状態で，側頭骨・中耳領域に出現することは稀とされる。これに対し，脳実質が硬膜の裂隙から脱出して同部に出現する例は，古くから脳膿瘍の術後や頭部外傷後の合併症としていくつかの報告がみられている。これら両疾患は1950年代以後，「耳性髄液漏」などの標題の陰にかくれてわずかに報告されていたにすぎなかつたが，近年，これらの疾患の報告が続き，再認識されはじめた感がある。

　われわれは12年前に真珠腫性中耳炎として乳突洞手術を受けた女子高校生が，「左耳から透明な水がでる」として来院した例において，外耳道後上壁が下垂腫脹し，拍動性をもつていることから，いまだ本邦に報告のない髄膜脳瘤の存在を疑い，手術的に治療し軽快せしめたので，ここに報告するとともに文献的考察を行なつた。

　A case of postoperative development of meningoencephalocele which penetrated into the mastoid bowl is presented.

　A 77 year-old girl was referred to us with thechief complaint of occasional "clear watery discharge from the left ear", that had started after a modified radical mastoidestomy which was performed 12 years ago.

　Physical examination revealed a pulsating sagging area on the posterior part of the external meatal wall. Tomographic studies of the mastoid region revealed a large defect in the tegmen antri. A diagnosis of cerebrospinal fluid otorrhea with brain hernia was made.

　Transmastoid approach was selected for repairing the cerebro-spinal fluid leakage. It was revealed that the meningoencephalocele had obliterated the whole mastoid bowl and partly adherent to the meatal skin. The size of the bony defect in the tegmen antri measured 15 mm in length anteroposteriorly, while its width was undeterminable.

　There was a defect of the dura covering the prolapsed brain tissue near the sinodural angle where the arachnoid membrane was visible. A free graft of the temporalis fascia was placed on the arachnoid to cover the dural defect. The meatal skin was lifted upwards and sutured to support the protruded tissues. The postoperative course was uneventful.