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 37-year-old-man was admitted to our hospital because of periodic contraction of the right shoulder muscles of approximately one month's duration. He denied any significant history such as trauma or fever. General physical examination was unremarkable. Neurological examination was also unremarkable except for the periodic synchronous myoclonus involving the right sternocleidomastoid, trapezius, deltoid, rhomboid and serratus anterior muscles. X-ray fluoroscopy demonstrated a synchronized rhythmic contraction of the right diaphragm. The myoclonus was considered to be of spinal origin, because those muscles were innervated by the right fourth and fifth cervical spinal segments. Its frequency was approximately 1.2 Hz. The myoclonus disappeared during sleep. It was enhanced by a voluntary contraction of the corresponding muscles, but mental stress such as arithmetic induced no change in the myoclonus. CBC, serum laboratory data including viral antibody titer, and cerebrospinal fluid were all normal. Radiological examination including MRI showed no abnormal finding. EEG as well as somatosensory evoked potentials following median nerve stimulation were normal. Jerk-locked averaging triggered by the myoclonus of the right deltoid muscle showed no pre-myoclonus spike at the scalp electrodes. Clonazepam (1.5-6 mg/day) and phenytoin (200 mg/day) reduced the rhythmicity as well as frequency of the myoclonus, which then became stimulus-sensitive. The reflex myoclonus was induced by tapping anywhere on the body or by electric shock, but not by flash or sound. There was a refractory period of approximately 800 msec. Lack of the stimulus-sensitivity early in the clinical course could be due to this refractory period.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A case of stimulus-sensitive segmental spinal myoclonus]. 275 58

Clonazepam (1 mg h.s.) and temazepam (30 mg h.s.) were studied in 10 patients diagnosed as having insomnia with nocturnal myoclonus. Each subject underwent two nocturnal polysomnographic recordings while drug-free, two during treatment with clonazepam, and two during treatment with temazepam. Treatment sessions were 7 days long, and recordings were done on nights 6 and 7 of the treatment sessions. A 14-day washout period separated the treatment sessions. The order of drugs used in the first and second treatment sessions was randomized. Objective and subjective sleep laboratory data showed that both drugs improved the sleep of patients with insomnia in association with nocturnal myoclonus. Neither drug significantly reduced the number of nocturnal myoclonic events. Sleep changes were consistent with those produced by sedative benzodiazepines in general. Thus, the data support clinical reports that clonazepam, a benzodiazepine marketed for the indication of seizure, is useful in improving sleep disturbances associated with nocturnal myoclonus. Temazepam, a benzodiazepine marketed for the indication of insomnia, was found to be a suitable alternative to clonazepam in the treatment of insomnia associated with nocturnal myoclonus. The present data and other studies suggest the need for a model that explains why leg movements and sleep disturbances may wax and wane independently.
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PMID:Nocturnal myoclonus: treatment efficacy of clonazepam and temazepam. 287 85

The clinical characteristics of 15 patients with essential myoclonus are evaluated. The course of illness was one of initial worsening followed by a stable or improved state. Only two patients had positive family histories of involuntary movements. Nine patients had segmental distribution despite a careful search for etiology; in two of these patients, myoclonus was rhythmic. The trunk and proximal limbs were the most frequently affected body regions. Clonazepam improved myoclonus in 10 of 13 patients, two of whom had complete resolution of symptoms. On review of the salient features of the myoclonus, we discerned four phenomenological subcategories: (a) oscillatory myoclonus, (b) rhythmic segmental myoclonus, (c) nonrhythmic segmental myoclonus, and (d) nonrhythmic multifocal myoclonus.
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PMID:Essential myoclonus. 308 Aug 50

Polygraphic sleep recordings were performed in two patients with nocturnal myoclonus. The beneficial effect of Clonazepam has been confirmed in the two cases.
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PMID:[Clinical and polygraphic study of 2 cases of "nocturnal myoclonus" sensitive to clonazepam]. 407 18

Startle disease is an autosomal dominant disorder with two phenotypic expressions. In the major form, there is hypertonia in infancy, and later an insecure gait. The patients have falling attacks without unconsciousness and in these, they are often injured or suffer concussions. Episodes of shaking of the limbs lasting for several minutes and resembling generalized clonus or repetitive myoclonus occur. These are most often nocturnal and are also unaccompanied by loss of consciousness. the patients are hyperreflexic and show an increased incidence of associated neurological and electroencephalographic abnormalities. The minor form of startle disease is only manifested by excessive startle and this is inconstant. In infancy it is brought out by febrile illness and in adult life by emotional stress. Gastaut and Villeneuve postulated the existence of a sporadic form of hyperekplexia different from the disorder described by Suhren et al. Review of their report and comparison with the cases of Suhren et al, and our own patients leads us to believe that the sporadic and familial forms of startle disease are the same. The disorder is rare, probably misdiagnosed initially as spastic quadriplegia, and later as epilepsy. Clonazepam appears to be the treatment of choice and its effect is sustained.
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PMID:Startle disease or hyperekplexia: further delineation of the syndrome. 677 25

Palato-pharyngo-laryngeal myoclonus is well-known clinical criterion characterized by persistent, rapid, repetitive, rhythmic muscle twitch the rate of which ranges 50-200 Hz. It appears in the palate, pharynx, larynx, diaphragma, and the ocular or limb muscles, but the most common combination of the distribution is palate-pharyngo-laryngeal type or only palatal type. In most instances the movement is synchronous, but others show asynchronous myoclonus at different rates. There was a case report in which an electrical stimulation given at the ulnar nerve produced reset of myoclonus indicating that some feedback mechanism has some influence in the generation of pacemaker activity in the brainstem. This myoclonus has been considered to result from interruption of any one fiber system in a olivocerebellorubrotegment-olivary equipotential reverating circuit, so-called Guillain-Mollaret triangle. As etiological factors, cerebrovascular accidents are the most common, but various other causes have been encountered including tumor, trauma, inflammation, multiple sclerosis, electroshock, dialysis encephalopathy, and other degenerative neurological diseases. Analysis of the symptoms is the most important cure of the diagnosis, and this myoclonus is relatively easily differentiated from other involuntary movement, but recently MRI is a very effective examination to detect a lesion in the medulla visualizing the degenerative changes of the lower olivary nucleus. Clonazepam, trihexyphenidyl, carbamazepine, 5HTP and caeruletin have been reported as effective agents for this movement.
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PMID:[Palato-pharyngo-laryngeal myoclonus]. 827 81

Periodic movements in sleep (nocturnal myoclonus) are characterized by a triple flexion of the ankle, knee and hip, which are particularly evident during 1-2 and 2-3 sleep stages. Iijima et al (1991) reported these movements in 5 out of 7 HAM patients, suggesting that nocturnal myoclonus is not rare in HAM. L-dopa and bromocriptine are reported to be the most effective. Spinal myoclonus (SM) is characterized by symmetric, rhythmic involuntary contractions of muscle groups supplied by one or several contiguous segments of the spinal cord. There has been only one case report of SM by Kanda et al (1988). Clonazepam and tetrabenazine are reported to be the most effective. Tremor is characterized by a sinusoidal oscillatory movement produced by synchronous or alternating contractions of reciprocally innervated antagonist muscles. Postural finger tremor was seen in about 40% of HAM patients (Suwazono et al, 1989). Painful, paroxysmal muscle contractions of the lower limbs were reported in only one patient with HAM by Ikeda et al in 1990. Based on electrophysiological findings, they were thought to be caused by reciprocal excitation in the spinal cord.
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PMID:[Movement disorders in HTLV-I associated myelopathy (HAM)]. 827 83

Three patients, aged 71, 50, and 41 years, presented with myoclonic activity arising in the relaxation period preceding sleep onset and causing severe insomnia. Polygraphic studies showed that the myoclonic activity began in spinally innervated muscles, propagating at low speed to rostral and caudal muscular segments. Myoclonus arose whenever patients relaxed mentally and showed diffuse electroencephalographic alpha activity and was independent of posture. The jerks disappeared during sleep. Clonazepam afforded symptomatic improvement. Propriospinal myoclonus arising from a spinal generator may be facilitated by changes in supraspinal control related to vigilance levels. When arising during relaxation and drowsiness, it may cause severe insomnia.
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PMID:Propriospinal myoclonus upon relaxation and drowsiness: a cause of severe insomnia. 899 56

For pure childhood absence epilepsy (CAE), ethosuximide (ESM) remains the drug of first choice. Although valproic acid (VPA) is of equal efficacy, it is more toxic, and is reserved for those patients with accompanying convulsions. Lamotrigine (LTG) is effective as both add-on and monotherapy for CAE. If any of these three drugs fails, one of the other two can be used as monotherapy. Rarely, when ESM, VPA, or LTG does not effectively control CAE, phenytoin (PHT), primidone (PRM), and phenobarbital (PB) may be partially effective, although carbamazepine (CBZ) may worsen absence seizures. Experience is limited with the newer AEDs. Tiagabine (TGB) may induce absence status epilepticus in PGE. Oxcarbazepine (OXC) and vigabatrin (VGB) may worsen absence seizures. Felbamate (FBM) is probably effective, but is potentially fatal. Lifelong therapy is not anticipated. For juvenile absence epilepsy (JAE), VPA is the drug of first choice. LTG is also of proven efficacy. The risks of VPA-induced teratogenicity (possibly lessened by the concurrent use of folic acid) and weight gain are potentially unacceptable in young women of childbearing age. Not enough data exists on the safety of LTG in pregnancy. A combination of VPA and LTG can be used if either drug alone is unsuccessful. For juvenile myoclonic epilepsy (JME), VPA is the traditional drug of first choice in most patients. As in JAE, side effects may make VPA an unacceptable choice in many patients, especially young women. In clinical practice, TPM is being increasingly used as monotherapy for JME. Many patients appreciate the accompanying weight loss seen with TPM, but it has potentially troubling side effects, has not been well studied as monotherapy for JME, and its safety in pregnancy has yet to be confirmed. PHT and CBZ may worsen myoclonus when used alone, but they may have a role as add-on treatment to VPA, LTG, or TPM, especially when generalized tonic-clonic seizures (GTCSs) are not controlled. PB and PRM may also be useful as add-on treatment, but often have unacceptable side effects. Clonazepam may be useful as adjunctive treatment for resistant myoclonic jerks. OXC and VGB both worsen myoclonic seizures. GBP is not useful in JME and can make seizures worse. The efficacy of FBM and TGB in JME is largely unknown. Lifelong AED therapy is necessary. In epilepsy with generalized tonic-clonic seizure (GTCS) on awakening (EGA), VPA is the drug of choice, especially if other seizure types (absence and myoclonic) are present. If only GTCSs are present, then PB, PHT, and CBZ may be as effective as VPA; however, the use of PHT and CBZ may "unearth" other seizure types (absence and myoclonic) in those patients with EGA, although PB is poorly tolerated. As for JME, LTG, and TPM may both be effective monotherapy for EGA, although the use of other AEDs in EGA has not been well studied. Lifelong AED treatment is necessary.
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PMID:Primary Generalized Epilepsies. 1109 77

Hyperekplexia (startle disease) is a rare non-epileptic disorder characterised by an exaggerated persistent startle reaction to unexpected auditory, somatosensory and visual stimuli, generalised muscular rigidity, and nocturnal myoclonus. The genetic basis is a mutation usually of the arginine residue 271 leading to neuronal hyperexcitability by impairing glycinergic inhibition. Hyperekplexia is usually familial, most often autosomal dominant with complete penetrance and variable expression. It can present in fetal life as abnormal intrauterine movements, or later at any time from the neonatal period to adulthood. Early manifestations include abnormal responses to unexpected auditory, visual, and somatosensory stimuli such as sustained tonic spasm, exaggerated startle response, and fetal posture with clenched fists and anxious stare. The tonic spasms may mimic generalised tonic seizures, leading to apnoea and death. Consistent generalised flexor spasm in response to tapping of the nasal bridge (without habituation) is the clinical hallmark of hyperekplexia. Electroencephalography may show fast spikes initially during the tonic spasms, followed by slowing of background activity with eventual flattening corresponding to the phase of apnoea bradycardia and cyanosis. Electromyography shows a characteristic almost permanent muscular activity with periods of electrical quietness. Nerve conduction velocity is normal. No specific computed tomography findings have been reported yet. Clonazepam, a gamma aminobutyric acid (GABA) receptor agonist, is the treatment of choice for hypertonia and apnoeic episodes. It, however, may not influence the degree of stiffness significantly. A simple manoeuvre like forced flexion of the head and legs towards the trunk is known to be life saving when prolonged stiffness impedes respiration.
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PMID:Hyperekplexia in neonates. 1152 14


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