軟骨無形成症に伴う広範脊柱管狭窄症に対する頚髄除圧術の1例

Decompression for Developmental Cervical Canal Stenosis in an Achondroplastic Adult : Case Report

　抄録：軟骨無形成症に広範脊柱管狭窄症が伴うことは知られているが，成人期における頚髄除圧術の報告は稀である．患者は軟骨無形成症の50歳女性で進行性の四肢の知覚障害，脱力，両上肢痛，後頭部痛および間欠跛行を有し，頚髄症JOAスコアは10.5点であった．画像所見では全脊椎レベルに脊柱管前後径の狭小化を認め，環椎では11mm，軸椎から第7頚椎まではいずれも10mmであった．症状は頚髄症と腰部脊柱管狭窄症が混在していたが，頚髄症の症状増悪傾向を重視し環椎後弓切除術とC3～C7脊柱管拡大術を施行した．手術後，後頭部痛の消失と神経症状の軽減を認め，術後4カ月でJOAスコアは13.5点に改善した．また，下肢症状もしびれの軽減，歩行距離の増大と改善を認めたため，腰椎については経過観察中である．

　Achondroplasia is well known for its frequent association of developmental spinal canal stenosis. However, there have been very few reports on decompressive surgery for cervical canal stenosis in adult patients. We report a case of a 50-year-old achondroplastic woman who was treated surgically for adult-onset cervical myelopathy. The patient presented with intermitted claudication, intractable and progressive neck/head pain, sensory disturbance in four extremities, and weakness in both hands. The Japanese Orthopaedic Association (JOA) score for cervical myelopathy was 10.5 points. Lateral radiographs demonstrated pan-spinal canal stenosis with the antero-posterior diameter being 11mm at the C1 level and 10mm at the subjacent 6 levels. The symptoms were considered to include those of cervical myelopathy and of lumbar canal stenosis, and cervical decompression was indicated first. Laminectomy of the atlas and expansive Laminoplasty from the C3 to C7 were performed. Short-term results were quite satisfactory with the headache having disappeared, myelopathy ameliorated, claudication markedly improved, and the JOA score elevated to 13.5 points at four months postoperatively.