頚椎片開き式脊柱管拡大術後C5麻痺の検討―両側partial foraminotomyの予防効果について

Prevention of C5 Palsy after Cervical Expansive Laminoplasty by Bilateral Partial Foraminotomy

　抄録：1989年以降に行った頚椎片開き式脊柱管拡大術305例のうち13例（4.3％）に主として第5頚神経領域の運動麻痺（以下C5麻痺）を経験した．麻痺症例が術前から易損性を有していたか否かを知るため術前の臨床所見，筋電図所見，頚椎柱弯曲指数，上関節突起前方突出度等について非麻痺例と比較したが有意差はみられなかった．また麻痺例にはC5領域の痛みを10例（77％）に，知覚障害を8例（62％）に伴っており根障害を疑わせる所見であったが，痛みを伴わない例も3例あった．麻痺発生までの期間は手術当日から術後28日まで分散していたが，5日以降に発生した例では全て座位や上肢自動運動など上肢の重量負荷を契機としていた．運動麻痺は全例が1年以内に筋力5まで回復した．一方予防対策として1993年以降C5，C6神経根に対してopen sideとhinge sideにpartial foraminotomyを行っており麻痺の発生は有意に減少した．

　The purpose of this study was to evaluate the effectiveness of bilateral partial foraminotomy in preventing the C5 palsy that can occur after cervical decompression operations. We analyzed 305 cases of cervical expansive laminoplasty performed for spondylotic myelopathy or ossification of the posterior longitudinal ligament (OPLL). Postoperative C5 palsy occurred in 13 (4.3％) of the 305 cases, radicular pain in 10 cases (77％), and sensory disturbances in 8 (62％). We assessed all neurological findings including X-ray, CT, and EMG findings, but no statistical differences were found in any of the preoperative clinical findings in relation to the occurrence of postoperative C5 palsy. Since 1993, we have been performing cervical expansive laminoplasty at the same time as bilateral partial foraminotomy as a means of preventing postoperative C5 palsy, and evaluate its prophylactic effect. We compared the rate of occurrence of C5 palsy in the foraminotomy group and the preceding non-foraminotomy group concerning. The results showed that C5 palsy occurred in 0.6％ of the patients in the foraminotomy group, as opposed to 4.0％ in the non-foraminotomy group (p＜0.05, Fisher's direct method).

　Conclusions：No specific risk factors for C5 palsy were identified among the preoperative clinical findings related to C5 palsy. Bilateral partial foraminotomy was effective in preventing C5 palsy after cervical expansive laminoplasty.