腰椎変性側弯症における凹側神経根障害―黄色靱帯による頭側神経根圧迫の2例

Cephalad Nerve Root Entrapment Caused by Ligamentum Flavum of Caudal in Tervertebra at the Concavity in Degenerative Lumbar Scoliosis

　腰椎変性側弯症では中心性狭窄・外側陥凹狭窄・椎間孔・椎間孔外狭窄が混在し，さらにすべりなど動的因子も複合して関与することが多いが，黄色靭帯が頭側の椎間孔狭窄の圧迫要因として注目されることは稀である．今回，側弯凹側の椎間孔入口部で黄色靭帯頭側付着部により頭側の神経根を圧迫し，上関節突起上縁の黄色靭帯部分切除で治療した2症例を経験した．Wedgingによる凹側椎間孔の骨性狭窄に加え，黄色靭帯のたわみとそれによる肥厚により頭側の椎間孔入口部での神経根の圧迫が術中所見で確認された．

　Degenerative lumbar scoliosis sometimes causes central canal stenosis, foraminal stenosis, or extraforaminal stenosis, which is associated with motion factors.　The foraminal portion of the ligamentum flavum has rarely been recognized as an entrapment factor of the upper nerve root.　We report two cases in which the foraminal portion of the ligamentum flavum compressed the cephalad nerve root at the entrance of the foramen in the concavity of degenerative lumbar scoliosis.　In addition to bony foraminal stenosis caused by disc wedging, buckling and hypertrophy of the ligamentum flavum can cause cephalad nerve root entrapment at the entrance of the foramen.