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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This is a proposal of the Movement Disorder Society for a clinical classification of tremors. The classification is based on the distinction between rest, postural, simple kinetic, and intention tremor (tremor during target-directed movements). Additional data from a medical history and the results of a neurologic examination can be combined into one of the following clinical syndromes defined in this statement: enhanced physiologic tremor, classical essential tremor (ET), primary orthostatic tremor, task- and position-specific tremors, dystonic tremor, tremor in Parkinson's disease (PD), cerebellar tremor, Holmes' tremor, palatal tremor, drug-induced and toxic tremor, tremor in peripheral neuropathies, or psychogenic tremor. Conditions such as asterixis, epilepsia partialis continua, clonus, and rhythmic myoclonus can be misinterpreted as tremor. The features distinguishing these conditions from tremor are described. Controversial issues are outlined in a comment section for each item and thus reflect the open questions that at present cannot be answered on a scientific basis. We hope that this statement provides a basis for better communication among clinicians working in the field and stimulates tremor research.
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PMID:Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee. 982 89

We prospectively studied motor symptoms in 32 patients with CT- or MRI-proven acute pure parietal stroke. A transient, mild, 'pseudoparesis' of the hand (90%), was noted, improved by visual attention and prompting, associated with non-awareness of muscle power (53%), transient soft pyramidal signs (50%), unilateral akinesia (100%) and motor hemineglect (37%) in non-dominant lesions. Lower motoneurone-type atrophy was not observed in this acute phase. We called 'poikilotonia' the striking unpredictable variations in muscle tone, ranging from extreme hypertonia to hypotonia, found in all patients. When maintaining postures, patients showed large oscillations (100%), laterodeviation or levitation of the arm (60%), especially in the case of large or posterior lesions, or, occasionally (3%), motor persistence or even hemicatalepsy (3%). Limb kinetic and manipulatory apraxia, with inadequate organization and anticipation of motor sequences and synergies, motor arrests, perplexity, unrecognizable gestures and loss of bimanual coordination, was a constant finding (100%). Other apraxias (62%) and difficulty in copying intransitive gestures of the hand (84%) were associated with posterior lesions involving the supramarginal gyrus. When reaching towards objects, all patients showed abnormal anticipatory hand shaping, but visuomotor ataxia (3%) was only seen with bilateral posterior stroke. Sensory (70%) or pseudocerebellar (4%) ataxia, was seen in both anterior and posterior lesions. Avoidance behaviors (34%) were not uncommon, but had no localizing value. Of the dyskinesias, hand dystonia (84%) was frequent, but athetosis (16%), asterixis (15%), postural tremor (15%), myoclonus (9%) and stereotypia (9%), were uncommon. The abnormal eye movements were unilateral hypo-akinesia of exploratory saccades (43%), abnormal ipsilateral pursuit and contralateral optokinetic nystagmus in the case of posterior lesions, and oculomotor apraxia with bilateral posterior lesions. In conclusion, parietal motor syndrome can be recognized during bedside examination, and probably reflects the loss of multiple sensory feedback to motor programs, especially those directed to the extrapersonal space.
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PMID:Parietal motor syndrome: a clinical description in 32 patients in the acute phase of pure parietal strokes studied prospectively. 987 53

Asterixis is a recognized but uncommon clinical sign of phenytoin toxicity. A case is presented in which asterixis and acute cerebellar dysfunction occurred when the phenytoin levels reached the toxic range. It disappeared when the drug levels normalized. Asterixis is now classified as a form of negative myoclonus, which is characterized by irregular myoclonic lapses of posture. The neurochemistry and physiology of phenytoin causing asterixis has yet to be elucidated.
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PMID:Phenytoin-induced asterixis--uncommon or under-diagnozed? 1103 Apr 57

CNS toxic effects of the antineoplastic agent ifosfamide (IFX) are frequent and include a variety of neurological symptoms that can limit drug use. We report a case of a 51-year-old man who developed severe, disabling negative myoclonus of the upper and lower extremities after the infusion of ifosfamide for plasmacytoma. He was awake, revealed no changes of mental status and at rest there were no further motor symptoms. Cranial magnetic resonance imaging and extensive laboratory studies failed to reveal structural lesions of the brain and metabolic abnormalities. An electroencephalogram showed continuous, generalized irregular slowing with admixed periodic triphasic waves indicating symptomatic encephalopathy. The administration of ifosfamide was discontinued and within 12 h the asterixis resolved completely. In the patient described, the presence of asterixis during infusion of ifosfamide, normal laboratory findings and imaging studies and the resolution of symptoms following the discontinuation of the drug suggest that negative myoclonus is associated with the use of IFX.
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PMID:Ifosfamide encephalopathy presenting with asterixis. 1208 48

Myoclonus is a sudden, abrupt, brief, 'shock-like' involuntary movement caused by muscular contractions ('positive myoclonus') or a sudden brief lapse of muscle contraction in active postural muscles ('negative myoclonus' or 'asterixis'). Various disorders can cause myoclonus including neurodegenerative and systemic metabolic disorders and CNS infections. In addition, myoclonus has been described as an adverse effect of some drugs. Level II evidence is available to indicate that levodopa, cyclic antidepressants and bismuth salts can cause myoclonus, while there is less robust evidence to associate numerous other drugs with the induction of myoclonus. The pharmacological mechanisms responsible for this adverse effect are not well established, although increased serotonergic transmission may be involved in the induction of myoclonus by several drugs. Drug-induced myoclonus usually resolves after withdrawal of the offending drug, but in some cases specific treatments are needed.
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PMID:Drug-induced myoclonus: frequency, mechanisms and management. 1472 56

Negative myoclonus, commonly known as asterixis, is often observed in patients with toxic-metabolic encephalopathies or focal brain lesions. It is a movement disorder characterized by postural lapses resulting from brief cessation of tonic muscular contraction. Negative myoclonus has a characteristic appearance on needle electromyography. Lapses in continuous postural muscle activity can lead to falls. This increased risk of falls makes it particularly important to recognize and treat negative myoclonus, especially in patients with multiple medical problems, deconditioning, and gait disturbances. To our knowledge, there have been no published reports implicating negative myoclonus as a cause of falls in adults. We present a case of asterixis as a cause of falls and near falls in a patient with metastatic breast cancer and normal mental status who was receiving gabapentin.
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PMID:Asterixis related to gabapentin as a cause of falls. 1614 53

A huge number of neurological disorders are associated with myoclonus. This paper describes these disorders whose diagnosis partly relies on the presence of myoclonus. The diagnostic approach is related to certain clinical features of myoclonus, which, after their integration in the clinical context, help orientate towards diagnosis. Myoclonus is frequent during dementia. Although its presence is well-known to take part in the diagnosis of Creutzfeldt-Jakob disease (CJD), myoclonus can also be present to a significant degree in Alzheimer's disease and Lewy body dementia (LBD), which raises a diagnostic issue. Both its clinical and electrophysiological features may help differential diagnosis, given that myoclonus with fast-evolving dementia and focal neurological signs should favor the diagnosis of CJD. Myoclonus in a context of progressive ataxia suggests one clinical form of the Ramsay-Hunt syndrome (progressive myoclonic ataxia, PMA), whose most frequent causes are: coeliac disease, mitochondriopathies, some spino-cerebellar degenerations, and some late metabolic disorders. In addition to ataxia and myoclonus, the presence of opsoclonus directs diagnosis toward the opsoclonus-myoclonus syndrome (OMS), whose origin, in adult, is idiopathic or paraneoplastic. Palatal tremor (myoclonus) with ataxia may represent either a sporadic pattern, which often reflects the evolution of degenerative or lesional disorders, or a familial pattern in some degenerative affections or metabolic diseases. Of more recent knowledge is the association of progressive ataxia, myoclonus, and renal failure, which corresponds to a recessive autosomic disease. In a context of encephalopathy, myoclonus is frequent in metabolic or hydro-electrolytic disorders, and in brain anoxia. One should distinguish these various forms of myoclonus which may occur in the acute post-anoxic phase, from those occurring as sequels at a later stage, i.e. the Lance and Adams syndrome whose clinical aspects are also multiple. Myoclonus is less frequent during toxic or drug exposures. Irrespective of its acute or insidious onset, Hashimoto's encephalopathy is accompanied by myoclonus and tremor. Myoclonus may also be present during encephalic and/or spinal infectious disorders. Myoclonus with focal neurological signs may be observed in thalamic lesions, responsible for unilateral asterixis or unilateral myoclonus superimposed on dystonic posture. Segmental spinal myoclonus or propriospinal myoclonus may be associated with several spinal-cord disorders. Myoclonus associated with peripheral nerve lesions is exceptional or even questionable for some of these.
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PMID:Symptomatic myoclonus. 1733 75

Negative myoclonus (NM) is an unspecific motor disorder that can characterize a variety of neurological conditions. From the clinical point of view, NM appears as a shock-like involuntary jerky movement caused by a sudden, brief interruption of muscle activity. Asterixis is a type of NM that occurs typically in toxic-metabolic encephalopathies. NM of epileptic nature, or epileptic negative myoclonus (ENM), is defined as an interruption of tonic muscle activity, which is time-locked to an epileptic EEG abnormality, without evidence of an antecedent positive myoclonia in the agonist-antagonist muscles. ENM can be observed in idiopathic, cryptogenic, and symptomatic epileptic disorders. Pathophysiological hypotheses on the origin of NM involve subcortical as well as cortical mechanisms. Recent neuroimaging and neurophysiologic investigations, including intracerebral recordings and electrical stimulation procedures in epileptic patients, suggest the participation of premotor, primary motor, primary sensory, and supplementary motor areas in the genesis of NM. Polygraphic monitoring is essential for the diagnosis of NM, allowing the demonstration of brief interruptions of a tonic EMG activity, not preceded by a positive myoclonus in the agonist and antagonist muscles of the affected limb. Simultaneous EEG-EMG monitoring demonstrating the association of NM with an epileptic potential is consistent with the diagnosis of ENM. Evolution and prognosis of NM is mainly related to aetiology. In childhood idiopathic partial epilepsy, ENM can respond to some drugs (in particular, ethosuximide), whereas other medications (such as carbamazepine or phenytoin) have been reported to induce or worsen it.
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PMID:Negative myoclonus. An overview of its clinical features, pathophysiological mechanisms, and management. 1733 79

Creutzfeldt-Jakob disease (CJD) is a degenerative disease of the brain associated with a rapidly progressive spongiform encephalopathy. Visual symptoms and neuro-ophthalmological signs are not infrequent, and presentation to an ophthalmologist may result. A case is reported of an 89-years-old gentleman who presented with a short history of isolated deterioration in vision. He underwent ocular intervention but subsequently developed progressive dementia, asterixis, myoclonus, cerebellar and extrapyramidal signs, and cortical blindness. An electroencephalogram was consistent with CJD. The patient progressively deteriorated and died 9 weeks after symptom onset. Limited post-mortem examination confirmed CJD.
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PMID:Vision loss due to coincident ocular and central causes in a patient with Heidenhain variant Creutzfeldt-Jakob disease. 1806 77

An array of movement disorders is associated with ethanol, illicit drugs, and tobacco. Heavy ethanol users experience withdrawal tremor and, less often, withdrawal parkinsonism, chorea, and myoclonus. Asterixis is a feature of hepatic failure. On the other hand, ethanol can ameliorate essential tremor and myoclonus-dystonia. Among opioid drugs, meperidine can precipitate myoclonus. Severe parkinsonism affected users of a synthetic meperidine analog contaminated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Spongiform leukoencephalopathy, sometimes with chorea and myoclonus, occurred in inhalers of heroin vapor (chasing the dragon). Psychostimulants including cocaine acutely cause stereotypies and dyskinesias. Phencyclidine toxicity causes myoclonus. Tobacco use, on the other hand, protects against Parkinson's disease. Clinicians need to consider substance abuse in patients with unexplained movement disorders.
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PMID:Substance abuse and movement disorders. 2072 28


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