Chiari I型奇形に頭蓋底陥入症を合併した1例

Surgical Treatment of Chiari I Malformation Associated with Basilar Invagination. Case Report

　Chiari I型奇形に頭蓋底陥入症を合併した1例の治療経験を報告する．症例は59歳の女性で，主訴は後頚部痛，歩行障害，嚥下障害だった．単純X線像で環軸椎不安定性を，MRIおよびCTで小脳扁桃の下垂および歯突起の頭蓋内への陥入を認め，頭蓋底陥入症を合併したChiari I型奇形と診断した．大後頭孔減圧術に加えて後方固定術を施行し，術後臨床症状は著明に改善した．頭蓋底陥入症を合併したChiari I型奇形の治療に関して確立した見解はないが，大後頭孔減圧術および後方固定を行うことは有効な治療であると考える．

　We report a case of Chiari I malformation associated with basilar invagination that was treated surgically.　A 59-year-old female presented at our hospital with neck pain, gait ataxia, and dysphagia.　X-ray films showed atlantoaxial instability, and CT myelography and MRI revealed caudal descent of the cerebellar tonsils through the foramen magnum and ventral brainstem compression by the odontoid process.　A diagnosis of Chiari I malformation associated with basilar invagination was made, and foramen magnum decompression and posterior OC-C3 fusion were performed.　The postoperative neurological and clinical findings showed marked improvement, and MRI revealed that the posterior cranial fossa was well decompressed.　Although the optimal treatment for patients with Chiari I malformation associated with basilar invagination remains unclear, it was successfully treated in our patient by foramen magnum decompression and posterior fusion.