Cervical meningeal cystとatlanto-axial dislocationを合併した1例

A CASE OF A CERVICAL MENINGEAL CYST WITH AN ATLANTO-AXIAL DISLOCATION

Ｉ．はじめに

　頸部のintradural meningeal cystは極めて珍しいものでlarge meningeal cystは報告例がなく，これまでに2例のarachnoid cystとperineural cystが1例報告されているにすぎない。その症状は，頸部痛，四肢麻痺，知覚障害などで，進行性，あるいは間歇性にくるといわれている^2）。歯状突起根部の骨折や軸椎の形成不全で歯状突起が軸椎椎体から分離しているとatlanto-axial　dislocationを生じることがあり，頸部痛，斜頸，四肢麻痺，知覚低下，myelopathyのみならず，痙攣や精神遅延や視力障害などの大脳症状の原因となることもある^16）。

　我々の症例は，頭部，胸部の外傷の10年後より発作性の頸部痛，後頭部痛をきたすようになり，レ線的にatlanto-axial dislocationを指摘され，myelographyにより偶然に頸部に広範なcystが発見された。症状はatlanto-axial dislocationというよりはcystによるものであると考えられ，手術によりcystとクモ膜下腔とを交通せしめて，症状の改善をみた。

A case of an intradual arachnoid cyst in the cervical region with an atlanto-axial dislocation was reported.

A 19 year-old male has been complaining paro-xysmal lancing nuchal and occipital pain for aboutlyears. During this period of time, severities and frequencies of these paroxysmes were gradually increasing. At the age of 3, he suffered from a dead injury causing unconciousness for one hour.

Radiological examination of the cervical spine revealed atlanto-axial dislocation with as odontoi-deum. A large cervical intradural meningeal cyst was accidentally discovered during a myelographic study on admission. The cyst extended from the 2nd to the 6th cervical vertebra to the left of the mid-line, and it was communicated with cervical subarachnoid space at the level between Cs and C6. Severe nuchal pain, which was induced by filling of the cyst with contrast medium, was releaved by evacuation of the cyst.

A lef hemilaminectomy was performed at the level of the fifth and sixth cervical vertebra. Total excision of the cyst was thought impossible due to dense adhesion of the dura with the cyst. A wide fenestration was made in the cyst wall aiming for free communication of the CSF between the cyst and the subarachnoid space. This surgery corn-pleted 1 year and 2 months ago, has been effective.

Histogically, the lateral and medial walls of the cyst, like the dura, consisted of collagen fibers with abundant collagen.

This cyst might have been formed by a rupture of the internal layer of the dura by a trauma as-sociated with a rupture of the arachnoid resulting in the flow of CSF breaking into the defect of the dura and dissecting its inner and outer layers. Narrowing of the communication between the cyst and the subarachnoid space produces retension of the CSF. This might be responsible for his clinical symptoms.

Intradural meningeal cysts in the cervical region are very rare. A report of a true cyst of a large size in this region has not appeared in medical references. A thorough discussion was made on the clinical, radiological, pathological, etiological characteristics and treatment of the cervical menin-geal cyst. Atlanto-axial dislocation was also briefly discussed.