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Query: UMLS:C0013421 (dystonia)
 8,418 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dystonia is generally considered a disease of basal ganglia. We report two patients with definite MS who acutely developed hand dystonia and athetoid movements. In both patients: 1) dystonia was electrophysiologically demonstrated by lack of reciprocal inhibition between antagonistic forearm muscles; 2) SEP from median nerve stimulation showed delayed cervical N13 and absent frontal and parietal components; 3) the long latency response after stimulation of median nerve of the affected hand was absent or delayed; 4) MRI showed lesions in the posterolateral cervical spine but no involvement of basal ganglia and thalami. We think that, in these cases, dystonia and athetoid movements could be ascribed respectively to the involvement of descending pathways regulating reciprocal inhibition of motoneurons and to the involvement of large diameter afferents due to the demyelinating lesion at the cervical level.
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PMID:Hand dystonia secondary to cervical demyelinating lesion. 794 58

This report describes a patient with degenerative type of progressive myoclonus epilepsy (PME), who showed slowly progressive deterioration of the central nervous system; intellectual impairment, dysarthria, and involuntary movements, particularly action myoclonus and dystonia. The patient was a 19-year-old woman who had no hereditary factors. At the age of 4, she developed action myoclonus in the upper limbs bilaterally. Her condition became gradually worse, and at the age of 15, she was admitted to our hospital because of involuntary movement in the upper limbs. First physical examination revealed mild mental retardation, action myoclonus, dystonia, and delayed adolescence. As giant SEP characteristic of PME and Ramsay Hunt syndrome was found, she was tentatively diagnosed as having Ramsay Hunt syndrome without epilepsy, and delayed adolescence. Now, she is 19 years old, and unable to walk alone because of involuntary movements and paralysis. But she has not developed epilepsy. As she has not been compatible with progressive myoclonus epilepsy (PME) and progressive myoclonic ataxia (PMA) classified by Marseille Consensus Group, she has been diagnosed as having an atypical PME syndrome.
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PMID:[A case of degenerative type of progressive myoclonus epilepsy]. 841

Myoclonus, defined as shock-like involuntary movement, may be physiological or caused by a very wide variety of hereditary and acquired conditions. Because myoclonus can originate from different disorders and lesions affecting quite varied levels of the central and peripheral nervous systems, it represents from many points of view a diagnostic challenge. Moreover, new entities have been recently individualized, such as cortical tremor, which deserve renewed attention. The aim of this review is to propose a rationale for a diagnostic approach based on clinical and electrophysiological grounds. In this setting, we successively address 1) the clinical features allowing a positive diagnosis of myoclonus; 2) the clinical clues to the etiology; 3) the relevance of the clinical context to the diagnosis; and 4) the contribution of neurophysiology. Differentiating myoclonus from tics, spasm, chorea and dystonia can be difficult, and a careful reappraisal of clinical features allowing precise identification is presented. Moreover, the topographical distribution of myoclonus, the temporal pattern of muscle recruitment, the condition of occurrence and the rhythm of the event, may provide clinical clues relevant to the diagnosis. Myoclonus without associated epilepsy, myoclonus with epilepsy, myoclonus with encephalopathy, parkinsonism and/or dementia represent overlapping clinical categories, although they remain useful for the diagnostic approach. Using electrophysiology (including back-averaging EEG, MEG, SEP, C-reflex studies) to determine the origin of myoclonus may not allow us to focus on the underlying condition. Indeed, in many instances, the myoclonus is cortical in origin, but the pathology is found elsewhere.
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PMID:[Myoclonus in the adult: diagnostic approach]. 1128 Oct 67

A 43-year-old man was admitted to our hospital due to unstable walking, head tilting to the left and difficulty in extending his arm. He was quite healthy until the age of 20 years, when these symptoms appeared and progressed slowly afterward. Due to his unstable walking, he started to use a wheelchair when he was 39 years old. He had no family history of similar disease. On admission, neurological examination revealed spasmodic torticollis, ataxic speech and marked limb and truncal ataxia. Myoclonic jerky flexion of the forearm was induced when he raised and extended his forearm. He also showed mild hyperreflexia in the lower limbs without pathological reflexes. He had weakness and atrophy of the left supraspinatus, infraspinatus, deltoid and biceps brachii muscles and mild superficial sensory impairment in the left axillary nerve territory due to cervical spondylotic radiculopathy of the left C5 root. MRI of the brain demonstrated severe bilateral atrophy of the cerebellar hemispheres and vermis but minimal atrophy of the cerebrum and brainstem. Because surface electromyography revealed continuous discharge with phasic components in the biceps and wrist flexor muscles on extending the upper limbs, the jerky flexion movement of the forearm was considered to be primarily dystonia. Although no giant SEP was observed, a C-response was detected in the long-loop reflex in response to right median nerve stimulation. Nuclear examinations showed diffuse hypoperfusion and decreased glucose metabolism in the cerebellum. Based on these findings, we hypothesized that cerebellar dysfunction may have induced severe dystonic movement resembling myoclonus. We would like to name this complicated involuntary movement an "arm thrust". This is the first case to be reported of sporadic, chronic, progressive cerebellar ataxia accompanied by severe dystonic movement, especially on stretching the forearms, that mimics myoclonic movement.
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PMID:[A case of cerebellar ataxia showing severe dystonia masquerading as myoclonic jerky movements on arm extension]. 1235 58

For some time, dystonia has been seen as purely a motor disorder. Relatively novel concepts published approximately 10 years ago also presumed that in the development of dystonic dyskinesias, only motor behaviour was abnormal. Neurophysiological observations of various types of dystonic disorders, which were performed using sophisticated electromyography, polymyography, H-reflex examination, long-latency reflex, etc., as well as new insights into the behaviour of dystonia, have urged the inclusion of sensory (particularly somatosensory) mechanisms into the pathophysiological background of dystonia. The major role has been considered to be played by abnormal proprioceptive input by means of the Ia proprioceptive afferents, with the source of this abnormality found in the abnormal processing of muscle spindle afferent information. However, neurophysiological investigations have also provided evidence that the abnormality in the central nervous system is located not only at the spinal and subcortical level, but also at the cortical level; specifically, the cortical excitability and intracortical inhibition have been revealed as abnormal. This evidence was revealed by SEP recordings, paired transcranial magnetic stimulation recordings, and BP and CNV recordings. The current concept of dystonic movement connects the abnormal function of somatosensory pathways and somatosensory analysers with the dystonic performance of motor action, which is based on the abnormality of sensorimotor integration.
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PMID:Dystonia: a disorder of motor programming or motor execution? 1246 50

In median nerve somatosensory evoked potentials, the cortical N35 amplitude sometimes exceeds the P25 amplitude (C3'/C4' referred to Fz; "enhanced N35" feature). Six hundred consecutive patient median nerve SEPs were retrospectively analysed and compared with 27 controls. The feature was more often present in patients with dystonia (62%) than in patients with other disorders (22%; relative risk for the condition 2.8; Fisher's exact p=0.003) or control subjects (7.4%; odds ratio 20; p=0.0006). Similarly, the feature was more often present in patients with myoclonus (38%) than in patients with other disorders (22%; relative risk 1.7; p=0.02) or control subjects (odds ratio 7.5; p=0.006). There was no clear relationship of the feature to short latency SEP abnormalities except in cases of myoclonus. Further comparison was made of the characteristics of 72 patients each, with and without the feature, whose short latency SEP components were normal. The relationship of the feature to dystonia or myoclonus held true in this case-controlled arm of the study. The sensitivity and specificity were 65% and 78% respectively for any form of dystonia; 43% and 79% respectively for any form of myoclonus. The feature was even more specific in both conditions when compared with controls (93%). Most cases of dystonia with an identifiable cause in this study were of secondary forms. It is known that this feature often occurs in association with "giant" SEPs in some myoclonic conditions. However, its occurrence in dystonia may be a useful new finding in an established test, helping to identify a condition where there is increasing evidence for disordered sensorimotor integration.
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PMID:The "enhanced N35" somatosensory evoked potential: its associations and potential utility in the clinical evaluation of dystonia and myoclonus. 1727 14