痙性斜頸の外科的治療について—Microvascular decompressionの有効例についての検討

SURGICAL TREATMENT OF SPASMODIC TORTICOLLIS: EFFECTIVENESS OF MICROVASCULAR DECOMPRESSION

　抄録　2例の痙性斜頸に対する手術経験から，本疾患に対する微小血管減圧術（MVD）の有効性につき検討した。1例目はantecollisのヶ一スで，副神経が蛇行したPICAと椎骨動脈に挟まれる形となっており，その減圧により症状が著明に改善した。2例目はretrocollisで，手術にて副神経に異常圧迫を認めなかったため，Dandyの両側C_1-3前根切離術を行なった。過去に痙性斜頸に対してMVDを行なった報告は本例を含め16例であるが，全例antecollisもしくはhorizontal typeであり，その圧迫部位はいずれも椎骨動脈の硬膜貫通部よりやや上でC₁歯状靱帯の高さまでにあった。この共通性は本疾患の発生メカニズム，即ち中枢性ミエリンと末梢性ミエリンの移行部の圧迫がその病因となるという可能性を示唆した。術前の諸検査のうちMVDの有効性を示し得るのは椎骨動脈撮影であり，その異常所見としてPICAの低位分岐や蛇行もしくは同部の異常血管網などが挙げられた。

We report two patients of spasmodic torticol-lis who underwent different types of surgery ac-cording to their pathogenetic mechanisms. Thefirst case was a 42-year-old man who had two years history of right-sided antecollis. EMG of the sternocleid muscle on the affected side showed pathological findings. Characteristic find-ings on the vertebral angiography were a low position of the branching of tortuous PICA. At operation, we confirmed sandwich-like compres-sion of left accessory nerve between the PICA and vertebral artery. Decompression of the nerve from these arteries led to a remarkable relief of the symptom. The second case was a 70-year-old man whose neck had been forced to bend backward ; retrocollis over two years. EMG study was negative. The vertebral angiography showed no abnormality, either. Because there was no evidence of vascular compression on both acces-sory nerves at surgery, we chose bilateral C_1-3 anterior root section which was effective in con-sequence.

We found so far sixteen cases of spasmodic torticollis in the literature including ours who were benefited by microvascular decompression (MVD). All of them presented antecollis or ho-rizontal type. The characteristic operative find-ing was the compression of the accessory nerve located at between the dural perforation of the vertebral artery and dural attachment of C_1-3 den-tate ligament. We can therefore propose a me-chanism that the compression at the junction of the central and peripheral myelin causes such a neuroexcitatory symptom as in cases of facial spasm and trigeminal neuralgia. Because the route of surgery is the same for both MVD and Dandy's anterior root section, MVD may be the treatment of choice when the vertebral artery is torturous or PICA originates at lower position.