難治性のgeneralized spasmによるのけ反り発作に対し，免疫グロブリン静注療法が著効したstiff-person症候群の1例

Successful Treatment of the Backward-bending Attack due to Generalized Spasm in Stiff-person Syndrome with Intravenous Immune Globulin Therapy

要旨　ジアゼパムやクロナゼパム治療に抵抗性のgeneralized spasmによるのけ反り発作に対して，ヒト免疫グロブリン（IVIG）静注療法が奏効した抗GAD抗体陽性のstiff-person症候群の男性例を報告した。本例は58歳時に右下肢と腰背部の筋硬直で発症し，ジアゼパム6mg内服で軽快していた。63歳時に再び，両下肢と腰部の筋硬直，のけ反り発作，左下肢に限局したpainful spasmが出現した。ジアゼパム18mg/日とクロナゼパム2.0mg/日の内服でpainful spasmは消失し，筋硬直も軽度改善したが，のけ反り発作に対しては無効であった。IVIG療法開始3日目にはのけ反り発作は消失し，つづいて筋硬直も改善し，10日目には階段昇降が可能になった。本例のように難治性ののけ反り発作を有する例に対してもIVIG療法は有用であると考えた。

　We report a 63-year-old man with stiff-person syndrome,who dramatically responded to the treatment with high dose intravenous immunoglobulin（IVIG）. He developed stiffness of the right leg and low back five years ago. He was treated with oral diazepam 6mg／day and showed a marked improvement. He had been maintained on the same dose since then. In 2000, he began to have episodic generalized spasm and painful spasm of his left leg as well as persistent stiffness of his legs and low back. Findings on the physical examination were normal except for a prominent hyperlordosis with co-contracture of the lumbar paraspinal and abdominal muscles. Neurologic examination revealed stiffness in the lower limbs, more marked on the left side, and lower truncal muscles. The left leg had painful spasm, which was provoked by tactile stimuli. There was severe generalized spasm which made him suddenly bend backward. These backward-bending attacks were provoked spontaneously or reflexively by sudden tactile stimuli. He was unable to arise from a chair or stand without assistance. His deep tendon reflexes on both legs were brisk and Babinski sign was negative. He had no diabetes mellitus and thyroid function was normal. Antibodies against glutamic acid decarboxylase（GAD）, antinuclear antibody, thyroid peroxidase autoantibody and antithyroglobulin autoantibody in the serum were present. His painful spasm was disappeared and muscle stiffness was moderately improved by treatment with oral diazepam and clonazepam, but backward-bending attacks due to generalized spasms were not controlled. He received IVIG. Three days after the administration of IVIG, these attacks disappeared completely. Subsequently muscle stiffness improved. One week after, he was able to walk without assistance. IVIG may be useful for treatment of generalized spasm, which had no response to treatment with diazepam or clonazepam.