軸椎歯突起後方偽腫瘍により頚髄症を呈した1例

Posterior Decompression and Spinal Fusion for Retro-odontoid Pseudotumor. Case Report

　非関節リウマチの軸椎歯突起後方偽腫瘍により頚髄症を呈した1例を経験したので報告する．症例は77歳の男性で，主訴は四肢不全麻痺であった．単純X線写真で第2頚椎以下が骨性に癒合し，環軸椎の不安定性を認めた．MRIでは腫瘤を歯突起後方に認め，脊髄が腫瘤と環椎後弓で圧迫されていた．後方除圧固定術を施行し，術後10カ月現在，腫瘤は縮小し症状は改善している．過去の歯突起後方偽腫瘍の報告の検討と今回のわれわれの経験から，歯突起後方偽腫瘍の手術には後方除圧固定が望ましいと考えられた．

　We report a case of retro-odontoid pseudotumor with chronic atlantoaxial instability.　A 77-year-old man presented at our hospital with tetraparesis.　X-ray films and CT myelography showed ossification of the anterior longitudinal ligament under C2 and atlantoaxial instability.　MRI revealed a retro-odontoid, extradural mass that severely compressed the adjacent spinal cord.　Treatment consisted of C1 laminectomy and posterior C0-C4 fusion.　The neurological findings and the patient's clinical condition improved postoperatively.　Reduction of the pseudotumor was demonstrated by MRI 4 months later.　Various reports have described surgical procedures for the treatment of retro-odontoid pseudotumor.　We reviewed those reports and our own case and concluded that posterior decompression and spinal fusion might be sufficient as a surgical procedure to treat retro-odontoid pseudotumor.