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

Action myoclonus secondary to posthypoxic encephalopathy is being seen increasingly with improved resuscitation techniques. A case report describes 5 specific physical and occupational therapeutic techniques for achieving independence in ambulation, transfers and self-care: (1) analysis and segmentation of complex motions into small steps; (2) controlled progression of training; (3) voluntary cessation of abnormal activity (pacing); (4) progressive densensitization to external stimuli; and (5) quantification of progress. Literature review suggests that posthypoxic action myoclonus is secondary to a loss of inhibitory synapses in the brainstem reticular formation due to low serotonin levels. The proposed therapeutic effect of clonazepam, the drug used in this patient, is decreased serotinin degredation. L-5-hydroxytryptamine, an investigative drug, is also therapeutic, for it stimulates increased serotonin production.
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PMID:Action myoclonus following acute cerebral anoxia. 42 May 69

Posthypoxic action myoclonus is usually associated with impaired serotonin (5-HT) neurotransmission but in some patients 5-HT precursors aggravate and 5-HT blockers improve action myoclonus. We studied a 65-year-old man who presented with action myoclonus following a prolonged episode of moderate hypoxia and severe hypercarbia. The myoclonus increased with 5-hydroxytryptophan (5-HTP) 1,200 mg/day plus carbidopa 300 mg/day and sodium salt of valproic acid (SVA) 800 mg/day, and improved with 1 mg of clonazepam (CNZ) in an intravenous bolus. Biochemical analysis of the cerebrospinal fluid (CSF) prior to any drug therapy did not reveal abnormalities in the levels of homovanillic acid (HVA) and methoxyhydroxyphenylglycol (MHPG) but 5-hydroxyindoleacetic acid (5-HIAA) levels were elevated in comparison with controls (33 versus 21 ng/ml). SVA therapy produced a moderate increase and 5-HTP plus carbidopa a threefold elevation of 5-HIAA in CSF and marked aggravation of action myoclonus. Methysergide (3 mg/day) totally suppressed myoclonus and decreased CSF 5-HIAA to undetectable levels. Methysergide also reduced CSF tryptophan to 40% of baseline levels. Discontinuation of methysergide and substitution by placebo was followed by reappearance of myoclonus. A partial and incomplete spontaneous remission of symptoms took place 7 months after the asphyxic episode. Action myoclonus and enhanced 5-HT neurotransmission may be present in patients in which acidosis reverses the effects of hypoxia on 5-HT neurotransmission.
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PMID:Clinical, biochemical, and pharmacological observation in a patient with postasphyxic myoclonus: association to serotonin hyperactivity. 245 56

Action myoclonus, reviewed in this chapter, is the term applied to arrhythmic muscular jerking induced by voluntary movement. It is made worse by attempts at precise or coordinated movement (intention myoclonus) and may also be provoked by certain sensory stimuli. The effective stimuli for action myoclonus is probably feedback from muscle afferents, although it may be initiated by corollary discharge from motor cortex to reticular formation before or at the onset of voluntary movement. The condition is usually associated with diffuse neuronal disease such as post-hypoxic encephalopathy, uremia, and the various forms of PME, although action myoclonus may be limited to one limb in some cases of focal cerebral damage. It is caused by hyperexcitability of the sensorimotor cortex (cortical reflex myoclonus) or reticular formation (reticular reflex myoclonus), or both. No consistent pathological change has been reported in autopsied cases of action myoclonus. The underlying disorder appears to be a loss of inhibitory mechanisms involving serotonin and possibly GABA as transmitter agents. The term PME is used for the association of myoclonus with degenerative changes in the nervous system which are commonly diffuse but may predominate in certain systems. There may or may not be associated tonic-clonic seizures, other manifestations of epilepsy, or dementia. Those cases of PME associated with Lafora inclusion bodies and cerebral storage diseases can be distinguished from the system degenerations. Systems which may be involved in the latter group include cerebellodentatorubral, pyramidal, extrapyramidal, optic, auditory, posterior columns and gracile and cuneate nuclei, spinocerebellar pathways, motor neurons of cranial nerves and anterior horns, and muscle fibers. Confronted with this diversity of pathological change, it seems unnecessary to make any clinical distinction between Ramsay Hunt syndrome and Unverricht-Lundborg syndrome (Baltic myoclonus) because cerebellar signs are found in patients described under both headings. Additional systems may be involved in individuals or families who are otherwise typical. All three names could well be joined in an eponymous title (Unverricht-Lundborg-Hunt disease) or the condition simply known as the systems degeneration type of PME, as Halliday (43) suggested. The cause of the condition (or spectrum of conditions) is at present unknown. Action myoclonus usually responds to sodium valproate or clonazepam, and some individuals, particularly those with posthypoxic myoclonus, improve with the administration of serotonin precursors.
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PMID:Action myoclonus, Ramsay Hunt syndrome, and other cerebellar myoclonic syndromes. 308 Aug 51

A 39 years old man with severe action myoclonus and epileptic seizure was reported. He had been in good health and worked as an occupational diver until August 16, 1966, when he had to dive into the sea bottom about 35 m deep without diving equipment. After finishing his work, he fell into unconsciousness and drowned. Sometime later, he was rescued and treated as decompression sickness. When he became alert, severe action myoclonus and epileptic seizure appeared. 8 years later, he was admitted to our hospital for rehabilitation. The danger of diving without equipment was indicated, because in sea bottom alveolar oxygen pressure (Pao2) is about 450 mmHg and alveolar air pressure 4.5 atmospheric pressure. In this condition patient could hold his breath longer time than in sea surface. When he finished his work and floated with muscle relaxing, however, his blood supply to the brain decreased. It was thought, therefore, that he fell into unconsciousness and drowned. In somatosensory evoked potentials (SEP) by median nerve stimulation, giat patterns were recognized but there were differences between SEP of myoclonus epilepsy and that of this patient. P50 and N70-80 were giant in him, suggesting that he had a brain stem disturbance. Since the inhibition system of fast conducted fiber did not work well in this state, the component of slow conducted fiber was magnified. Action myoclonus may be due to the disturbance of inhibition system in the brain stem.
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PMID:[A Lance-Adams syndrome of a diver (author's transl)]. 679 51

Authors report a case of focal action myoclonus due to a localized hemispheric lesion. The woman had cardiac arrest complicated by ischemic stroke involving the left parietal region. Action myoclonus of the inferior right limb was the sole residual complaint, provoked by movement and maintenance of posture. Patient noted that myoclonus was worsened by carbamazepine and vigabatrin. EEG-EMG polygraphic study demonstrated action myoclonus and showed a particular EEG activity consisting in a volley of spikes on the vertex region during the right inferior limb movements. Contralateral movements did not elicit this activity. Pharmacological response to clonazepam, piracetam and alcohol was studied. A marked improvement of myoclonus was obtained with alcohol. Pathophysiology of this exceptional form of cortical action myoclonus is discussed.
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PMID:[Myoclonus of focal action and localized hemispheric lesion. A polygraphic and pharmacological study]. 748 88

The clinical and physiological characteristics of myoclonus in 14 patients with corticobasal degeneration are described. The myoclonus was focal, confined to one limb (usually the arm) and was most prominent on voluntary action or in response to sensory stimulation. On clinical inspection, the myoclonus appeared to occur at rest but EMG recordings revealed that apparently spontaneous myoclonus occurred only on a background of more or less continuous muscle activity (responsible for the rigidity and dystonia). The jerks consisted of hypersynchronous short duration bursts of EMG activity coincident in agonists and antagonists. Reflex myoclonus in hand muscles, to stimulation of the median nerve at the wrist, had a latency of approximately 40 ms. In 13 of the 14 patients reflex myoclonus was not associated with enlargement of the cortical sensory evoked potentials (SEPs); the later components of the parietal SEP were poorly formed and dominated by a broad positive wave with a peak latency approximately 45 ms. Prefrontal components of the SEP were relatively preserved, but there were no significant differences between the SEPs evoked from myoclonic and non-myoclonic limbs. Action myoclonus was not preceded by an identifiable cortical wave in the electroencephalogram back-averaged before each jerk. Magnetic, but not electric, brain stimulation evoked repetitive bursts of myoclonus suggesting enhanced cortical excitability. The combination of focal, predominantly distal, hypersynchronous jerks, evidence of enhanced cortical excitability, together with the known cortical pathology in corticobasal degeneration suggests that the myoclonus in these patients may be cortical in origin. Since the latency of reflex myoclonus in corticobasal degeneration is only 1-2 ms longer than the sum of the afferent and efferent times to and from the cortex, we propose the reflex myoclonus is mediated by direct sensory input to motor cortical areas that activate corticospinal tract output. Such myoclonus differs from the typical form of cortical reflex myoclonus in which reflex jerks have a longer latency (50 ms in hand muscles), cortical SEPs are enlarged and action myoclonus is preceded by a cortical discharge. It is proposed that these various forms of cortical myoclonus can be explained by the presence of different cortical relays of sensory information to cortical motor areas. The myoclonus of corticobasal degeneration may represent enhancement of a direct sensory input to the motor cortex. In contrast, the more widely recognized variety of cortical reflex myoclonus may involve abnormal relays through sensory cortex to motor cortex, either directly or via cerebellar-thalamo-cortical projections.
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PMID:The myoclonus in corticobasal degeneration. Evidence for two forms of cortical reflex myoclonus. 795 99

One of the difficulties in evaluating myoclonus in childhood is the lack of a standardized scale which addresses the constraints of pediatric scoring. The scale needs to be simple and rapid as well as sensitive and semi-quantitative and applicable across different ages. We videotaped children and young adults with myoclonus of various etiologies, such as progressive myoclonus epilepsy, opsoclonus-myoclonus and other acquired etiologies, and scored the videotapes using a new scale. Each clinical type of myoclonus (spontaneous, action and sensory-evoked myoclonus) was graded separately on a five-point scale for severity, intensity and distribution. Data were evaluated as separate scores and also combined for a total score. Validity and reliability were tested using a judge panel of three blinded, trained observers. Action myoclonus was the predominant form of myoclonus in our patients, and was significantly greater than spontaneous and sensory-evoked myoclonus in frequency, intensity and distribution. Separate statistical analysis performed for progressive myoclonus epilepsy and for opsoclonus-myoclonus showed the same pattern. Total scores between etiologies of myoclonus for frequency and distribution categories were significantly different. Subscores and total scores were highly correlated. We found the new scale to be flexible and adaptable for children and there were few missing values due to non-applicability of a scale item. It was useful for all pediatric age groups. The scale and videotape instructions provide a reliable tool for use in pediatric myoclonic disorders.
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PMID:A sensitive and semi-quantitative pediatric myoclonus evaluation scale. 856 45

Action myoclonus-renal failure syndrome (AMRF) is a distinctive form of progressive myoclonus epilepsy associated with renal dysfunction. The syndrome was not recognized prior to the advent of dialysis and renal transplantation because of its rapidly fatal course if renal failure is untreated. The first and only description of AMRF was in four French Canadian patients in three families (Andermann et al., 1986). We now describe 15 individuals with AMRF from five countries, including a follow-up of the four French Canadian patients, allowing a more complete characterization of this disease. Our 15 patients with AMRF belong to nine different families. Segregation analyses were compatible with autosomal recessive inheritance. In addition, our findings show that AMRF can present with either renal or neurological features. Tremor (onset 17-26 years, mean 19.8 years, median 19 years) and progressively disabling action myoclonus (onset 14-29 years, mean 21.7 years, median 21 years), with infrequent generalized seizures (onset 20-28 years, mean 22.7 years, median 22 years) and cerebellar features are characteristic. Proteinuria, detected between ages 9 and 30 years in all cases, progressed to renal failure in 12 out of 15 patients within 0-8 years after proteinuria detection. Brain autopsy in two patients revealed extraneuronal pigment accumulation. Renal biopsies showed collapsing glomerulopathy, a severe variant of focal glomerulosclerosis. This study extends the AMRF phenotype, and demonstrates a more extensive ethnic and geographic distribution of a syndrome originally believed to be confined to individuals of French Canadian ancestry. The independent progression of neurological and renal disorders in AMRF suggests a unitary molecular lesion with pleiotropic effects. Our results demonstrate that the renal lesion in AMRF is a recessive form of collapsing glomerulopathy. Genes identified for focal segmental glomerulosclerosis and involved with the function of the glomerular basement membrane and related proteins are thus good candidates. Treatment can improve quality of life and extend the lifespan of these patients. Dialysis and renal transplantation are effective for the renal but not the neurological features, which continue to progress even in the presence of normalized renal function; the latter can be managed with anti-myoclonic and anti-epileptic drugs.
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PMID:Action myoclonus-renal failure syndrome: characterization of a unique cerebro-renal disorder. 1538 27

We conducted an open-label, dose-finding, blinded-rating trial of gamma-hydroxybutyric acid (Xyrem) in a single patient with severe alcohol-responsive posthypoxic myoclonus refractory to treatment with standard antimyoclonic agents. Xyrem was given in divided doses during the day and was well tolerated. Intensity of myoclonus was measured using the Unified Myoclonus Rating Scale, and blinded videotape review demonstrated complete resolution of myoclonus at rest and stimulus-sensitive myoclonus. Action myoclonus and functional performance also improved in ways that were practically meaningful, allowing her to feed herself, to accomplish daily hygiene tasks, and to walk with assistance. The possible mechanisms of action and potential uses of this agent in other alcohol-responsive movement disorders are discussed.
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PMID:Marked amelioration of alcohol-responsive posthypoxic myoclonus by gamma-hydroxybutyric acid (Xyrem). 1575 Oct 49

Lance-Adams syndrome, described in 1963, is caused by anoxia of central nervous system, generally in the course of primary respiratory failure. It is characterized mainly by action myoclonus, associated cerebellar ataxia and very mild intellectual deficit. Occurrence of Lance-Adams syndrome is rare; about 100 cases have been described yet. The authors present the case of Lance-Adams syndrome in 36-year-old woman with many years' bronchial asthma. Three times acute cardiopulmonary arrest appeared during status asthmaticus. After successful cardiopulmonary resuscitation action myoclonus developed with cerebellar syndrome, aphonia, dysphagia and generalized convulsive seizures of tonic-clonic type. Electroencephalography showed polyspikes and complex of polyspikes-slow wave, synchronized with myoclonus. CT of the brain was normal. Action myoclonus responded appropriately to sodium valproate. The authors indicate the importance of the correct diagnosis and proper treatment.
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PMID:[Lance-Adams syndrome in patient with anoxic encephalopathy in the course of bronchial asthma]. 1720 60


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