後方除圧後に腫瘤縮小を認めた歯突起後方偽腫瘍の1例

Retroodontoid Pseudotumor Shrinking after Cervical Spinal Decompression. Case Report

　除圧術のみで腫瘤が縮小した歯突起後方偽腫瘍の78歳の男性例を経験した．主訴は2年半前からの右上下肢のしびれ感，両上肢脱力感であった．単純X線像では環軸関節不安定性は認めず，MRI・CTMでは歯突起後方偽腫瘍による頚髄圧排像を呈した．後方除圧術で症状の改善を認め，経時的に腫瘤は縮小し脊髄の形態も改善した．術後の環軸椎の不安定性の出現も認めなかった．環軸関節不安定性のない本症の治療法には様々な報告があるが，除圧術のみでの治療も考慮されてよいことが示唆された．

　Retroodontoid pseudotumor is an inflammatory lesion associated with chronic atlanto-axial instability. Some reports hold that posterior stabilization is necessary for pseudotumor reduction. We report a case of a 78-year-old man with myelopathy due to a retroodontoid pseudotumor found in MRI and myelography. Laminectomy of the atlas and laminoplasty of the axis without stabilization were done because no atlanto-axial instability was shown in radiological evaluation. After surgery, neurological findings and clinical condition improved. The pseudotumor shrank within one year of surgery. Although various reports describe surgical treatment for retroodontoid pseudotumor without atlanto-axial instability, indications and methods of surgery remain undetermined. Our outcome suggests that posterior decompression for the spinal cord might be sufficient if retroodontoid pseudotumor has no atlanto-axial instability.