後頭蓋窩減圧術後C1後弓の再生により再狭窄を来したキアリⅠ型奇形の1例

Chiari Malformation (Type 1) with Regeneration of Removed C1 Lamina after Foramen Magnum Decompression ： a Case Report

Ⅰ．はじめに

　キアリ1型奇形に対しforamen magnum decompression（FMD）は有効な外科的治療と考えられるが，効果不十分や再発のため再手術を要する症例もある．われわれはFMDおよび硬膜の外層切開を行ったあと，減圧が不十分であったことに加え，骨性要素の再生による再狭窄のため，再手術を行った1例を経験した．キアリ奇形における再手術の原因として減圧部の骨再生が一因となった報告は少なく，今回文献的考察を加えて報告する．

We present the case of a 20-year-old female who underwent foramen magnum decompression and laminectomy of C1-C3 as well as incision of only the outer layer of the dura, for her symptomatic Chiari malformation (type 1) with syringomyelia, at the age of 9 years. She required additional surgery with removal of regenerated bone and dural plasty for the remaining and recurrent stenosis. The remaining stenosis may have been caused by the use of a technique without dural plasty and insufficient decompression of the bony structure. Further, the regeneration of C1 lamina could have been responsible for the recurrent stenosis. Her symptoms, which included gait disturbance, hypesthesia, excessive sweating, and nocturnal enuresis, manifested themselves when she was at the age of 2 years and progressed since that time. These symptoms didn't improve after the first surgery. However, after the second surgery, the gait disturbance and nocturnal enuresis were partially resolved.

　It is rare for new bone generation to necessitate reoperation. However, It should be noticed that careful followup is important after decompressive surgery for Chiari malformation in young patients.