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)

Behavioral responses to atropine in rats exposed to the potent anticholinesterase agents Soman and Sarin were studied. Atropine itself produced limb-shakes and certain stereotyped activities, in a dose-dependent manner. The neurotoxicity elicited by Soman and Sarin was antagonized by atropine, while at the same time the responses induced by the latter were attenuated. In contrast, where rats were challenged with atropine 6-72 h after giving single doses of Soman or Sarin, the limb-shake myoclonus was markedly enhanced. The atropine-induced stereotypies were not, however, significantly affected, except for an increase seen at 24 h after Sarin treatment. Repeated treatment with Soman for 3 wk also led to similar supersensitivity of atropine-induced responses. The peripheral muscarinic receptor antagonist, methylatropine, produced no such hyperactivity on its own or at any time after anticholinesterase exposure. The rapid occurrence of hypersensitivity to antimuscarinic compounds following exposure to these anticholinesterases, therefore, suggests the need for observation of subjects who are poisoned with such agents and treated with antimuscarinics, for adverse reactions such as myoclonus during the critically sensitive period, especially if repeated antimuscarinic therapy is carried out.
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PMID:Hypersensitivity to antimuscarinic agents following brief exposure to Soman and Sarin. 370 76

Following single or repeated treatment with the irreversible anticholinesterase, DFP or, during infusion of the muscarinic receptor agonist, oxotremorine, and the reversible anticholinesterase physostigmine, effects of challenges with muscarinic antagonists were studied in rats. The antagonists, atropine, scopolamine, benztropine, orphenadrine and trihexyphenidyl induced, to a low degree, limb-shakes (myoclonus) and stereotyped behaviors in normal rats. However, within 24-72 hr after the above pretreatments, this myoclonus was significantly enhanced. The anticholinergic-stereotypies were also increased but only by severe cholinergic pretreatment and at a time later than that for the myoclonus. Myoclonus and stereotypies are known to be produced by treatments which directly enhance serotonergic and dopaminergic activities, respectively. It is suggested that during prolonged cholinergic stimulation, the cholinergic-monoaminergic balance in the brain can be altered depending upon the degree of stimulation. This could be responsible for the observed differential onset of changes in the anticholinergic-behavioral responses, which could, in turn, be mediated by different monoaminergic (serotonin and dopamine) systems.
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PMID:Rapid induction of supersensitivity to muscarinic antagonists-induced motor excitation by continuous stimulation of cholinergic receptors. 404 Oct 2

Rett syndrome (RS) is one of the most frequent causes of mental retardation in females. As there are no known biochemical, genetic, or morphological markers, diagnosis is based on clinical phenotype including severe dementia, autism, truncal ataxia/apraxia, loss of purposeful hand movements, breathing abnormalities, stereotypies, seizures, and extrapyramidal signs. Myoclonus, although reported in some series, has never been characterized. We studied 10 RS patients, age 3 to 20 years, and observed myoclonus in 9. Severity of myoclonus did not correlate with that of the other symptoms or with age. Multifocal, arrhythmic, and asynchronous jerks mainly involved distal limbs. Electromyographic bursts lasted 48 +/- 12 msec. Burst-locked electroencephalographic averaging generated a contralateral centroparietal premyoclonus transient preceding the burst by 34 +/- 7.2 msec. Motor evoked potentials showed normal latencies, indicating integrity of the corticospinal pathway. Somatosensory evoked potentials were enlarged. The C-reflex was hyperexcitable and markedly prolonged (62 +/- 4.3 msec), mainly due to increase in cortical relay time (28.4 +/- 4.5 msec). We conclude that RS patients show a distinctive pattern of cortical reflex myoclonus with prolonged intracortical delay of the long-loop reflex.
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PMID:Cortical reflex myoclonus in Rett syndrome. 954 28

Comprehensive clinical evaluation of tics includes (1) assessments to diagnose (a) akathisia, myoclonus, stereotypies, and other dyskinesias and (b) their frequent behavioral concomitants, including attention deficits, compulsions, obsessions, and other psychopathologic manifestations, (2) descriptions of movement parameters from the patients, their parents, teachers, and important others, and (3) precise topographical localization of tics.
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PMID:Clinical assessment of tics. 1172 50

Tics, patterned movements distinct from stereotypies, myoclonus, and other hyperkinetic movements, are quite common in children, particularly among those with developmental and psychiatric disorders. Thus, tics can indicate the presence of atypical neurodevelopment or broader difficulties with cognition or mood. Tics are also the cardinal feature of Tourette syndrome, a childhood-onset neurobehavioral disorder characterized by a chronic inability to suppress or an urge to perform patterned, repetitive movements. Patients with Tourette syndrome most commonly have, in addition to tics, symptoms of inattention, hyperactivity, obsessiveness, or anxiety. Achieving the most effective treatment of a child with tics is contingent on proper diagnosis of the movement disorder and thorough assessment for other problems, followed by consideration of both nonpharmacologic and pharmacologic interventions for any and all symptoms interfering with the child's function and quality of life. This review focuses primarily on the diagnosis and medical treatment of tics in children and adolescents with Tourette syndrome.
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PMID:Treatment of children and adolescents with tics and Tourette syndrome. 1697 Aug 70

Rett syndrome (RS) is one of the best human models to study movement disorders. Patients evolve from a hyperkinetic to a hypokinetic state, and a large series of abnormal movements may be observed along their lives such as stereotypies, tremor, chorea, myoclonus, ataxia, dystonia, and rigidity. The aim of this work was to analyze movement disorders in RS patients with a detected MECP2 mutation, as well as their correlation with genotype, in a clinically and genetically well-characterized sample of patients, and thus contribute to redefine the clinical profile of this disease. In this study, we included 60 patients with detected MECP2 mutations. These were categorized and grouped for analysis, according to (1) type of change (missense or truncating, including nonsense and frameshift but also large deletions) and (2) location of the mutation. Differences were found concerning the frequency of independent gait, dystonia, type of tremor, and global score severity when comparing the group of patients with missense and truncating mutations. We also found differences in the presence, distribution, severity, or type of movement disorders in the two groups of patients according to the median duration of the disease (less than 60 months; 60 months or more). We conclude that movement disorders seem to reflect the severity and rate of progression of Rett disorder, patients with truncating mutations presenting a higher rate and more severe dystonia and rigid-akinetic syndrome, when comparing groups with similar time of disease evolution.
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PMID:Movement disorders in Rett syndrome: an analysis of 60 patients with detected MECP2 mutation and correlation with mutation type. 1851 55

Myoclonic jerks and myoclonic status (MS) are sometimes difficult to distinguish clinically from movement disorders such as hand stereotypies, tremor, and dystonia in Rett syndrome. We describe a rare and complete video-polygraphic study of a girl with Rett syndrome (MECP2 mutation) and MS misdiagnosed as movement disorders and disclosed after video-polygraphic recordings. Corresponding to closely recurring activity of diffuse spike and polyspikes-wave-type paroxysms, rhythmic and, especially, arrhythmic myoclonias, usually asymmetrical and asynchronous, involving mainly right muscle deltoid and rarely followed by an inhibitory phenomenon, appeared. The MS improved and, most importantly, disappeared after the use of levetiracetam, with an evident antimyoclonic efficacy and a marked improvement of daily life for the patient and her caregivers. The difficulty in differentiating some typical nonepileptic behavioral features and movement disorders of patients with Rett syndrome from seizures was overcome using prolonged video-polygraphic recordings in our case.
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PMID:Myoclonic status misdiagnosed as movement disorders in Rett syndrome: a video-polygraphic study. 1960 60

Neurologic paraneoplastic syndromes (NPSs) result from damage to the nervous system due to the remote effects of cancer not related to metastasis, infection, or metabolic derangements. NPSs are rare, affecting 1 in 10,000 patients with cancer. Pathogenesis is likely related to the immune mechanisms: normal neural tissue is mistakenly attacked due to the similarity in the onconeural antigens expressed by the tumor cells. Among the various "classic" and other NPSs, this review focuses on paraneoplastic movement disorders, including ataxia due to cerebellar degeneration, stiff-person syndrome, opsoclonus-myoclonus syndrome, chorea, parkinsonism, and tremor. The recently described syndrome of paraneoplastic anti-N-methyl-D-aspartate receptor encephalitis is also included, given that these patients have complex movements such as stereotypies and dyskinesias in addition to psychiatric symptoms, altered sensorium, and other neurologic signs. Although variable, treatment and prognosis of NPSs rely heavily on treatment of the underlying malignancy and immunotherapy.
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PMID:Paraneoplastic movement disorders. 1951 80

Parkinson's disease, the most common hypokinetic movement disorder, has received much attention from the clinical and scientific community, but there has been a relative paucity of comprehensive reviews of hyperkinetic disorders, even though they are equally or even more disabling. Hyperkinetic movement disorders include tremors, dystonia, chorea, tics, myoclonus, stereotypies, restless legs syndrome, and various other disorders with abnormal involuntary movements. Substantial progress has been made in the understanding of the role of the basal ganglia in the pathophysiology of these hyperkinesia disorders and in motor control, muscle tone, posture, and cognitive processes. Although therapies that target pathogenesis are still lacking, effective management of hyperkinetic movement disorders demands that physicians are knowledgeable about current and novel pharmacological and surgical approaches. In addition to tetrabenazine, a monoamine-depleting drug, new formulations of botulinum toxin are being increasingly used in the treatment of these movement disorders. Finally, success with surgical approaches, particularly deep brain stimulation in patients with Parkinson's disease who have levodopa-induced dyskinesias, has been extended to the treatment of many hyperkinetic movement disorders.
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PMID:Treatment of hyperkinetic movement disorders. 1967 76

Inborn errors of metabolism (IEM) are a group of genetic disorders characterized by dysfunction of an enzyme or other protein involved in cellular metabolism.(1) Most IEMs involve the nervous system (neuro-metabolic diseases or NMD). NMD often present with a complex clinical picture: psychomotor retardation and/or regression, pyramidal signs, ataxia, hypotonia and epilepsy and movement disorders.(1) Movement disorders are more frequently part of this complex picture than a predominant symptom, however in some instances the clinical picture may be summarized in an invalidating movement disorder.(2) On a phenomenology basis, one can distinguish eight main types of movement disorders: dystonia and athetosis, chorea, tremor with or without parkinsonism, ballismus, myoclonus, tics and stereotypies. Most of these abnormal involuntary movements generate from a dysfunction or a lesion in the basal ganglia, excepting myoclonus, the origin of which can vary (cortical, brainstem, basal ganglia, spinal and even peripheral nervous system).(3) Classically the most frequently observed movement disorders in NMD are: dystonia, myoclonus, chorea, tremor and parkinsonism (Fig. 1). The primary goal of this article is, departing from the literature and a large personal series, to describe the types of movement disorders most frequently observed in NMD and to discuss their clinical value in the setting of specific types of NMD.
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PMID:Movement disorders in neuro-metabolic diseases. 2001 70


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