SAH 発症の椎骨解離性動脈瘤（vertebral artery dissecting aneurysm: VADA）は，可及的早期に 治療を行うことがコンセンサスである．解離部を含む母動脈閉塞が原則である．低侵襲で，血管撮 影室で診断に続き治療できるメリットは大きく，方向は血管内治療にシフトしている．しかし，減 圧開頭やbypass を要するposterior inferior cerebellar artery（PICA） involved type には開頭術が必要で，穿 通枝温存も開頭術に分がある．開頭術減少の原因の一つは，体位が複雑で術野も深く，低位脳神経 に触れる可能性が高い側臥位による方法が，盲目的に踏襲されてきたことと考える．一方で，腹臥 位は体位が単純で術野が広く浅いためVA clip と同時にoccipital artery（OA）-PICA bypass がスムース に可能．減圧開頭が容易．というメリットがあり，広く一般化しやすい．VADA の治療は，発展し ていく血管内治療と開頭手術の技術を再考，伝承し，よりバランスのとれた治療をめざしていくこ とがこれからの方向性である．

Musculoskeletal trunk with 76 degree of freedom driven by thin McKibben muscles has been developed. Trunk mechanism of conventional musculoskeletal robots is simplified or underactuated and do not have all muscles of human because it is difficult for conventional actuators to be attached. Because thin McKibben muscles are small enough to be densely attached, we can overcome these problems by applying them to the back of the musculoskeletal robot.

Musculoskeletal back mechanism with 56 degree of freedom driven by thin Mckibben muscles has been developed. Back mechanism of conventional musculoskeletal robots is simplified or underactuated and do not have all muscles of human because it is difficult for conventional motors to be attached. Because thin McKibben muscles are small enough to be densely attached, we can overcome these problems by applying them to the back of the musculoskeletal robot.

  Introduction : Surgical approachs for ventrally located spinal tumors at the craniovertebral junction (CVJ) remains to be controversial. There are two major concerns. The first is that, the approaches may injure the spinal cord owing to the tension during surgical manipulations. The second concern is that, various problems associated with postoperative spinal instability, malalignment, atrophies of the paraspinal muscles, and axial pain may occur. Here, we present a posterolateral transmuscular (PLTM) approach aimed at reducing these concerns.

  Patients : From 2003 to 2012, 7 patients with ventrally located tumors at the CVJ were treated at Tominaga Hospital via the PLTM approach without additional posterior fixation. The patients had the following conditions : C2 neurinomas in 3 patients, C3 neurinomas in 2, and meningiomas in 2. All tumors extended ventrally across the midline. All patients presented with progressively worsening radiculomyelopathy and/or nuchal pain.

  Methods : The angle between the plane of the tumor-cord interface (TCI) and the plane parallel to the posterior surface of the vertebral body was determined. The PLTM approach was then classified into two varieties depending on this angle (TCIA). When the TCIA was more than 40°, a medial-PLTM approach was selected. When the TCIA was less than 40°, a lateral-PLTM approach was selected. A linear vertical skin incision was made 2-3 cm lateral from the dorsal midline in the medial-PLTM approach and 6-8 cm lateral from a dorsal midline in the lateral-PLTM approach. The length of this incision was 1-2 cm greater than the maximum sagittal length of the tumor. The lamina and facets were resected on the ipsilateral side, while preserving>50% of the facet. Depending on the vertical location of the tumors, other approaches were selected to avoid splitting and/or retracting muscles. Such approaches include the one via the suboccipital triangle, where the suboccipital muscles were retracted that was performed when the tumor was located at the C0-2 level. Another approach was via the area between the inferior oblique and multifidus muscles, which was performed when the tumor was located at the C2-3 level. With the availability of these options, tumors can be approached with minimal splitting and/or retracting of the paraspinal muscles and can be removed without or the minimum need for spinal cord retraction.

  Results : In all the patients, gross total tumor removal was performed, and the patients' symptoms either disappeared or were markedly alleviated. No postoperative instability was observed in any patients ; no additional spinal fixation was needed, and no postoperative neurological complications, including axial pain, occurred.

  Conclusion : The PLTM approach described here is very useful because it is minimally invasive. Tumors at the CVJ can be removed safely and easily under direct observation via the ventral area of the TCI plane while preserving musculoskeletal integrity.

　頚椎は，脊椎の中で最大の可動域を有し，環軸椎という軸椎下の椎骨と大きく形態を異にする椎骨の存在のために，そのバイオメカニクスは脊椎の中でも独特である．近年の3次元動作解析により，生体内での頚椎前後屈，回旋，側屈のすべての基本運動の詳細な挙動が明らかにされ，中でも回旋や側屈における椎間レベルの可動域や，カップルドモーションと呼ばれる3次元的な運動パターンの解明が，飛躍的に進んだ．頚椎疾患の治療に携わる医療従事者にとって，頚椎のバイオメカニクスを理解しておくことは重要である．そこで本稿では，バイオメカニクスの中でもリハビリテーションにおいて，特に重要と思われる頚椎の機能解剖やキネマティクスを中心に取り上げ解説する．

  Objective : Posterior cervical fixation using pedicle screw technique and rod system is increasingly chosen a procedure for stabilization and reconstruction of the cervical spine ; however, it has inherent risks that are unique. We focused on the feasibility of posterior cervical fixation using pedicle screw technique, especially for cervical myelopathy associated with athetoid cerebral palsy, for rheumatoid arthritis, and for destructive spondyloarthropathy.

  Methods : Consecutive 22 patients with cervical spine instability associated with athetoid cerebral palsy, with rheumatoid arthritis, or with destructive arthropathy treated with posterior cervical fixation using pedicle screw technique were retrospectively reviewed. All surgeries were performed with the help of fluoroscopy and neuronavigation system.

  Results : In all cases, posterior fixation according to preoperative plan was accomplished, and the postoperative courses were good. No vascular or neurological complications such as nerve root problem occurred.

  Conclusion : Long-term follow-up evaluation is essential, particularly for patients with athetoid cerebral palsy, rheumatoid arthritis, or destructive arthropathy because the natural course of these disorders is very progressive and more destructive than that of usual cervical spondylosis.