Delayed segmental axial dystonia of the trunk on standing after lumbar disk operation.

We report four patients with various degrees of chronic, tonic, mildly painful, or non-painful, kyphoscolioses in orthostatism, which developed weeks, or months, after one or several laminectomies for lumbar disk hernia, in the absence of recurring radicular pain or acute lumbar pain. No family history or personal antecedent, of focal or generalized dystonia was found and the dystonia was not seen in any of the four patients pre-operatively, or during the immediate post-operative period. Only ill-defined lumbar 'discomfort', unlike their pre-operative lumbago, was reported by the patients, before and during the occurrence of the pathologic trunk posture on standing. Asymmetric lumbar muscle tonic contraction and hypertrophy was found on physical examination. In all patients, the kyphoscoliosis was maximal when standing, partially disappeared when seated, and completely when lying down. One patient responded well to clonazepam, but the other three showed no improvement with either clonazepam or local injections of botulinum toxin; L-dopa was ineffective in all cases, and trihexiphenidyle in three.