Dumbbell type cervical neurinomaに対する後方到達法の工夫:椎間関節を温存した部分的片側椎弓切除法

Surgical approach for cervical dumbbell type neurinoma:posterior approach by partial hemilaminectomy with preservation of a facet joint

I．はじめに

　頸椎のdumbbell型神経鞘腫に対する手術療法は，1960年Cloward^2）が前方到達法による手術を報告して以来，後方到達法，側方到達法，さらには前方後方同時到達法などが試みられているが，画一的なものはない．報告の多くが腫瘍の進展方向の違いによる手術法選定に注目しており，術後高率に見られる頸椎の不安定性や彎曲変形に註及しているものは少ない．今回われわれはC2，C3レベルの硬膜内外を占拠し，拡大したC2／C3椎間孔から傍椎体部に進展したdumbbell型神経鞘腫を，術後の頸椎安定性保持を目的に，椎間関節，棘突起を温存し，C2,C3の部分的片側椎弓および横突起削除で摘出しえたので報告する．

We report on a case harboring a cervical dumbbell type neurinoma. The tumor was completely removed by a modified posterior approach, consisting of partial hemilaminectomies of C2 and C3 with preservation of the facet joint. The operative field under microscope was limited by the preserved facet joint of C2/3. However, sufficient bulk reduction of the epidural and paravertebral mass enabled us to obtain a good opera-tive field. The paravertebral mass, which extended anteriorly to just beside the posterior aspect of the carotid sheath, was removed through the lateral space.The operative field was easily widened beside the right facet joint of C2/3 with partial removal of the posterior part of the transverse process of C2 and C3. The transit portion of the tumor to the normal nerve fiber was also identified through this space. The intracanalicular mass was removed by the partial hemilaminectomies of C2 and C3 without compressing the dural sac. Following sufficient reduction of the bulk, the right vertebral artery was identified at the anteromedial margin of the enlarged intervertebral foramen. Finally the intradural part of the tumor was removed through this space.

Our modified posterior approach is a less invasive method to the bony elements of the cervical vertebrae and may minimize the incidence of postoperative insta-bility and angular deformity. This approach also elimin-ates the necessity of long postoperative immobilization using a rigid cervicothoracic brace.