Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A patient is described with severe intention myoclonus which was made worse by treatment with L-Dopa and improved by clonazepam. Family history and examination of several siblings suggested the diagnosis of Huntington's disease. Subsequent to improvement of the myoclonus the patient appeared to have the rigid form of Huntington's disease. This case represents a unique expression for an otherwise well defined genetic abnormality. Stimulus activated myoclonus in a common feature of a number of disorders of the nervous system. Intention, or action myoclonus has been the subject of increasing interest because of its association with the syndrome of post-anoxic encephalopathy (1), although it may occur with other disorders as well. Many abnormal movements have been reported in Huntington's disease, but myoclonus is a relatively uncommon feature of this disorder and to our knowledge intention myoclonus has not been reported as a major symptom. We recently have evaluated a patient with disabling intention myoclonus and examined several members of his family who have typical Huntington's disease. We therefore report this case, a unique presentation of an otherwise well described movement disturbance.
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PMID:Intention myoclonus in Huntington's disease. 13 56

Twelve parkinsonian patients on long-term levodopa therapy developed intermittent, myoclonic body jerks. The movements consisted of single unilateral or bilateral abrupt jerks of the extremities and occurred most frequently during sleep. Although directly related to daily dosage of levodopa, the myoclonus was specifically blocked by the serotonin antagonist, methysergide. Levodopa-induced myoclonus may be related to intermittent increases of activity of serotonin in the brain and results from levodopa-induced dysregulation of serotonin activity.
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PMID:Levodopa-induced myoclonus. 107 21

Levodopa-induced dyskinesias (LID) in Parkinson's disease (PD) may be classified into three main categories: "On" dyskinesias, diphasic dyskinesias (DD), and "off" periods. The study of 168 parkinsonian patients showed that about half (n = 84) showed one pattern of LID only. A combination of two was present in 68, and 16 had the three presentation patterns. A fairly good correlation between type of dyskinesia and presentation pattern was established. Chorea, myoclonus, and dystonic movements occurred during the "on" period. Dystonic postures, particularly affecting the feet, were mainly present in the "off" period, but a few patients had a diphasic presentation. Repetitive stereotyped movements of the lower limbs always corresponded to DD. Acute pharmacological tests using dopamine agonists (subcutaneous apomorphine 3-8 mg; intravenous lisuride 0.1-0.15 mg) and dopamine antagonists (intravenous sulpiride 200-400 mg and intravenous chlorpromazine 25 mg) were performed in 40 patients. Dopamine agonists enhanced "on" dyskinesias and markedly reduced or abolished "off" period dystonia and DD. Dopamine antagonists reduced all types of LID but usually aggravated parkinsonism. These clinical and pharmacological results indicate that LID in PD are a heterogeneous phenomenon difficult to explain on the basis of a single pathophysiological mechanism.
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PMID:Levodopa-induced dyskinesias in Parkinson's disease: clinical and pharmacological classification. 135 58

We demonstrated previously that electrical stimulation of the Flexor Reflex Afferents (FRA) induces a late flexion reflex with a central conduction time longer than 100 msec. Its latency is prolonged by increasing the intensity or the duration of the stimulation. This late reflex is therefore similar to the late flexion reflex observed in acute spinal cat with DOPA. Some findings suggest that in man the late flexion reflex could be inhibited at a premotoneuronal level by contralateral FRA stimulation. In relation to the late flexion reflex, a late contralateral facilitation of soleus monosynaptic reflex (MSR) was observed. Rhythmical activity was observed in only one patient who had an exceptional form of spinal myoclonus. This myoclonus could be modulated by FRA stimulation. These facts show that the reflex organization in paraplegic patients is similar to the one described in acute spinal cat with DOPA and therefore suggest that a spinal stepping generator could exist in humans.
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PMID:Late flexion reflex in paraplegic patients. Evidence for a spinal stepping generator. 265 69

In this review, the authors present a critical overview of the historical development, indications, complications, operative techniques, and results of procedures for the alleviation of the major dyskinesias. Emphasis is placed upon recent refinement of technique, particularly stereotaxis, as well as neurophysiologic stimulation and recording, computerized tomographic scanning (CT) and magnetic resonance imaging (MRI). Specific disorders that may be amenable to surgical therapy include spasticity secondary to spinal cord pathology, cerebral palsy, and multiple sclerosis; the tremor and rigidity of Parkinson's disease; essential tremor; dystonia; spasmodic torticollis; post-traumatic and postinfarction intention tremor; cerebral palsy with tremor; hemiballismus; myoclonus; and dyskinesias induced by L-DOPA.
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PMID:Neurosurgical management of spasticity, rigidity, and tremor. 332 80

Two patients with presumed encephalitis lethargica are presented with clinical features suggestive of two forms of the disease described by Von Economo: One patient had a psychosis and a mute-akinetic syndrome associated with myoclonus. The second patient presented with a psychosis and fever, developing severe dyskinesias involving the mouth, trunk and limbs, together with respiratory irregularities and presumed hypothalamic disturbance and disturbance of consciousness. In both cases, initial cerebrospinal fluid (CSF) examination revealed an elevated white cell count (predominantly lymphocytes), elevated protein in case 2, and oligoclonal bands in both cases. Computed tomography (CT) brain scan was normal but in both cases EEG revealed diffuse slow wave activity. A 18F-Dopa positron emission tomography (PET) scan in case 2 was normal. The medical management of both patients is discussed. In case 1, L-Dopa improved the akinesia, while the myoclonus responded to clonazepam. In case 2, the severe dyskinesias failed to respond to a number of drugs, and she ultimately required paralysis to relieve her almost continuous movements. Both patients responded rapidly and dramatically to intravenous methylprednisolone. We suggest that steroid treatment should be considered in the acute phase of patients with features suggestive of encephalitis lethargica.
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PMID:Clinical features and management of two cases of encephalitis lethargica. 915 30

Corticobasal degeneration (CBD) was first reported by Rebeiz et al as corticodentatonigral degeneration with neuronal achromasia in 1967. After Gibb et al described 7 cases including 4 cases from the literature under the term of corticobasal degeneration, CBD has become widely recognized. The disease starts mainly in one's fifties and sixties with the duration of 6 to 7 years. The clinical features include asymmetric parkinsonism, cerebral cortical signs, and others. Typically, patients present with unilateral clumsiness with akinetic-rigid syndrome and limb-kinetic apraxia. Postural instability, gait disturbance and involuntary movements such as dystonia are not uncommon. The parkinsonism is DOPA-resistant. BEsides apraxia, alien limb syndrome, cortical sensory disturbances, frontal lobe-release signs, and dementia are representative cortical signs. Other clinical features include dysarthria, pyramidal tract signs and supranuclear gaze palsy. MRI, SPECT or PET reveals asymmetric atrophy, decrease in blood flow or reduction in metabolism of the frontal parietal region around the central sulcus. Electrophysiological and magnetic stimulation studies demonstrated increase in excitability of the cerebral cortex. Myoclonus in CBD is cortical in origin but without any preceding potential or giant somatosensory evoked potential. Neuropathologically CBD is characterized by involvement of the particular cortices and substantia nigra. Other structures such as the putamen, pallidum, thalamus, subthalamus, cerebellar dentate nucleus and brainstem are affected to various extents. Histological features include achromatic, ballooned neurons as well as tau and Gallyas positive neuronal and glial intracytoplasmic inclusions. Astrocytic plaque is considered to be a form of glial inclusions specific to CBD. Diagnosis of typical cases of CBD appears easy but atypical cases were reported with showed dementia or aphasia as a main feature, or were devoid of the asymmetry of signs and symptoms. CBD, progressive supranuclear palsy and Pick's disease share both clinical and neuropathological features to some extent while they are clearly distinct among typical cases. The etiology and pathomechanism of CBD remain to be elucidated.
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PMID:[Corticobasal degeneration]. 957 68

Forty patients affected by severe Parkinson's disease (PD) were treated with tolcapone as an adjunctive therapy to L-DOPA, for 3-7 months, until this drug was discontinued because of side-effects (2 diarrhoea, one of them with orthostatic hypotension, 2 increments of liver enzymes) or because of mandatory indications of the European drugs authority. All patients, after 3-6 months of L-DOPA therapy adjustments, received entacapone for 3 months again followed by withdrawal. L-DOPA daily dosage was significantly reduced by tolcapone and entacapone (p = 0.01 and 0.05). "On" time was increased by 15% during tolcapone treatment (p < 0.05), and by 8% during entacapone treatment. "Off" time was decreased by 16% during tolcapone and by 7% during entacapone treatment. Entacapone was withdrawn in the same patient who experienced diarrhoea and orthostatic hypotension during tolcapone because of recurrence of side-effects, in 6 patients because of increment of dyskinesias (with hallucinations) and in 1 patients because of rhythmic, jerking myoclonus.
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PMID:Switch-over from tolcapone to entacapone in severe Parkinson's disease patients. 1145 77

The authors report a kindred in which GTP-CH deficiency resulted in a myoclonus-dystonia syndrome. The proband, a 17-year-old boy, presented with early-onset myoclonus and later, dystonia and bradykinesia. Blood prolactin was increased and CSF homovanillic acid, 5-hydroxyindoleacetic acid, and biopterin were all reduced. L-Dopa/carbidopa administration resulted in clinical improvement. In the paternal branch, the grandfather and three relatives had myoclonus-dystonia and resting or postural tremor of limbs. The authors found a missense mutation in the exon 6 of GCH-1 gene (K224R).
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PMID:Autosomal dominant GTP-CH deficiency presenting as a dopa-responsive myoclonus-dystonia syndrome. 1239 38

L-DOPA-induced dyskinesias are a common problem, occurring in about one third of parkinsonian patients after five years of treatment. Young age of onset, disease severity, duration of therapy and total dose of L-DOPA are the variables that best correlate with the development of dyskinesias. The first manifestations of dyskinesia are usually dystonic and involve the foot homolateral to the side most affected by Parkinson's disease. With time, dyskinesias may be classified in three main categories: off dystonia, diphasic dyskinesias also called onset and end of dose dyskinesia and peak dose dyskinesia. Although this classification is very useful in clinical practice, the different types of dyskinesia frequently overlap in a single patient when the disease progresses. Other types of involuntary movements such as myoclonus, a tremor with an increased amplitude and akathisia have been described. The physiopathology of L-DOPA-induced dyskinesias remains unclear but synaptic plasticity in striatal neurons seems to be a major phenomenon in the development of dyskinesias. Some rating scales have been developed to assess the intensity and severity of dyskinesias but their usefulness is still matter of debate.
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PMID:[L-DOPA-induced dyskinesia] 1269 Mar 19


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