Idiopathic adult onset action dystonia of the lower limbs: case reports

Abstract

Lower limb dystonia (LLD) usually heralds a generalized primary dystonia syndrome in children, particularly DYT 1 [4]. In adults, the syndrome is much less common and rarely associated with a genetic cause [3, 5, 6, 10–12]. We describe two cases of idiopathic action-induced LLD. A 52-year-old woman came to our institution with a 3-year history of walking difficulties. Clinically, dystonia was observed only while walking, with worsening after a few steps. The abnormal movements consist of an initial excessive flexion of the right thigh, followed by an exaggerated external rotation of the right leg. (Video, segment 1) Neurological examination was otherwise normal. The involuntary movements were not observed while walking up stairs, down stairs, sideways, backwards, and over a straight line; deterioration was observed while running, walking fast, barefoot, and on wet floor. There was no previous exposure to dopamine antagonists, no history of psychiatric disorders, pending litigation or secondary gain at work. Blood count and hepatic function tests were normal. Genetic test for DYT 1 was negative. Electromyography (EMG) and brain MRI were normal. Lumbar spine MRI showed mild spondylosis without nerve root compression. The patient received treatment with amitriptyline, levodopa, and trihexyphenidyl, without significant improvement. A 54-year-old woman came to our institution in 1999 for evaluation of right thigh pain suggestive of sciatica. Neurological examination showed action dystonia while walking down stairs, with increased flexion of the right thigh at the beginning of the movement, accompanied by mild external rotation of the leg, foot dorsiflexion, and toe extension (Video, segment 2); these involuntary movements were first noticed in 1990, and were not disabling. Dystonia improves considerably while going up stairs, descending backwards and walking on a flat surface. The left leg was not affected. Maneuvers to test root compression were negative. There were no arguments for a psychogenic phenomenon such as influence of distraction or suggestion. There was no history of mood disorders. EMG and lumbar spine MRI showed mild root compression. She received oral analgesics and physical therapy. The thigh pain resolved 1 year later. Dystonia was left untreated due to lack of physical limitation. After 20 years, LLD has mildly improved without functional or anatomical spreading. We present two cases of a rare type of action-induced LLD, without arguments supporting a psychogenic etiology. Pure psychogenic gait disturbance resembling LLD seems to be a very rare phenomenon [1]. Adult onset LLD should ordinarily raise the suspicion of Parkinson’s disease, [2] but this seems unlikely in our patients, as both had long and stable evolutions without other extrapyramidal manifestations. Electronic supplementary material The online version of this article (doi:10.1007/s00415-011-5989-x) contains supplementary material, which is available to authorized users.