長期透析患者に発生した頸椎後縦靱帯肥厚症による脊髄症

Myelopathy caused by hypertrophy of the posterior longitudinal ligament of the cervical spine in a patient with long-term hemodialysis

I．はじめに

　脊髄症を起こす重要な疾患の1つとして頸椎後縦靱帯骨化症（ossification of the posterior longitudinal liga—ment：OPLL）はよく知られているが^{1,2,6,14,17）}，後縦靱帯肥厚症（hypertrophy of the posterior longitudinal ligament：HPLL）に関してはその病因論を含めて解明されていない点が多い^12,15,26）．

　われわれは長期透析患者に発生したアミロイド沈着を伴ったHPLLによる脊髄症に対し，前方到達法による脊髄の減圧を行った後，頸椎を用いた自家骨による固定を行い，良好な結果を得られた1症例を経験したので，文献的考察を加えて報告する．

A 48-year-old female was admitted to our hospital because of progressive gait deterioration over a period of 4 months. She had been treated by hemodialysis for 14 years after bilateral nephrectomy. She originally suf-fered achondroplasia. Otherwise she was a healthy woman.

Neurological examination showed weakness and hypesthesia below C₅, accelerated deep tendon reflexes and inability in walking. T₁ weighted magnetic reso-nance imaging revealed severe cord compression from C₄ to C₆ due to an epidural isointensity mass located in the ventral surface of the dura. This mass was en-hanced by a contrast medium. Anterior decompression followed by an autogenous vertebral bone graft at C_4/5 and C_5/6 was performed. The posterior longitudinal ligament was remarkably thickened resulting in severe cord compression. Histologically this thick ligament contained amyloid deposition both in the superficial and deep layers. Ossification was not noticed in the ligament. Diagnosis of hypertrophy of the posterior lon-gitudinal ligament (HPLL) was made. HPLL is known to be frequenthy associated with herniated interverte-bral discs or segmental ossification of the posterior lon-gitudinal ligament (OPLL).

Myelopathy in this patient with long-term hemodialy-sis was aggravated by HPLL without ossification due to imbalance of systemic metabolism such as amyloido-sis. The authors report a unique case of HPLL caused by amyloidosis as one of the complications of chronic hemodialysis with special emphasis on its pathophy-siology and management.