[Surgical treatment of spasmodic torticollis: effectiveness of microvascular decompression]

We report two patients of spasmodic torticollis who underwent different types of surgery according to their pathogenetic mechanisms. The first case was a 42-year-old man who had two years history of right-sided antecollis. EMG of the sternocleidal muscle on the affected side showed pathological findings. Characteristic findings on the vertebral angiography were a low position of the branching of tortuous PICA. At operation, we confirmed sandwich-like compression 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 accessory nerves at surgery, we chose bilateral C1-3 anterior root section which was effective in consequence. 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 horizontal type. The characteristic operative finding was the compression of the accessory nerve located at between the dural perforation of the vertebral artery and dural attachment of C1 dentate ligament. We can therefore propose a mechanism 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.(ABSTRACT TRUNCATED AT 250 WORDS)