p,p'-DDT-induced alterations in brain serotonin metabolism

Since p,p'-DDT-induced myoclonus is ameliorated by serotonin agonists and aggravated by serotonin antagonists, the effect of p,p'-DDT on serotonin metabolism in rat brain was examined. p,p'-DDT (600 mg/kg intragastrically) elevated plasma tryptophan as well as tryptophan and 5-hydroxyindoleacetic acid concentrations in all seven regional areas of the brain assayed. Serotonin levels were elevated only in the midbrain and cerebellum of p,p'-DDT-treated rats. p,p'-DDT increased serotonin turnover in the medulla and midbrain. p,p'-DDT had no effect on the transport of 5-hydroxyindoleacetic acid out of the central nervous system, serotonin uptake and release from nerve terminals, or serotonin receptor binding in the brain. The findings in this study do not support a brain serotonin deficiency hypothesis as the explanation for the response of p,p'-DDT-induced myoclonus to serotonin agonists.     

Palatal myoclonus in postinfectious opsoclonus myoclonus syndrome : a case report.

An adult male presenting with acute onset opsoclonus, myoclonus and cerebellar ataxia is being reported. Patient had myoclonus involving limbs and palate. There are only a few reported cases associated with palatal myoclonus. Patient showed gradual spontaneous recovery. Possibility of underlying malignancy was excluded by detailed investigations.     

Cortical myoclonus in Janz syndrome.

OBJECTIVE: To evaluate the characteristics of EEG paroxysms and the relationship between EEG spikes and ictal myoclonic jerks in patients with juvenile myoclonic epilepsy (JME). METHODS: Six patients with a typical form of JME entered the study and underwent computerized polygraphic recordings. In each patient, the inter-peak spike interval was measured on repeated EEG bursts, and jerk-locked back averaging was performed on ictal epochs using a time window including the 100 ms before and the 100-200 ms after the point at which the jerk-related EMG potential diverged from baseline. RESULTS: In all cases, the myoclonic jerks were associated with polyspike waves (PSW) complexes. The frequency of repeated spikes within the PSW complex ranged from 16 to 27 Hz. Jerk-locked averaging revealed a positive-negative EEG transient with maximal amplitude on the frontal leads, which preceded the myoclonic jerk by 10.25+/-0.96 ms. A delay of 9.50+/-1.73 ms was measured between the jerk-locked positive peak detected on the frontal EEG leads of the two hemispheres; a comparable time lag was observed between the onset of myoclonic jerks in the two deltoid muscles. CONCLUSIONS: Our data suggest that the ultimate mechanism responsible for ictal myoclonic jerks in JME is largely similar to that sustaining cortical myoclonus in more severe pathological conditions such as progressive myoclonus epilepsies, despite the different pathogenic substrate and triggering mechanisms.     

Segmental facial myoclonus in moebius syndrome.

Moebius syndrome is characterized by sixth and seventh nerve palsy and is usually the result of bilateral hypoplasia or aplasia of the respective brain stem nuclei. There have been no reports of involuntary facial movements associated with this malformative complex. We report on a 6-year-old boy affected by Moebius syndrome with asymmetric involvement and segmental facial myoclonus with onset at age 2 years, affecting the side with partially conserved motility. Clinical presentation included congenital peripheral palsy of the right seventh cranial nerve and left-sided rhythmic rising of the upper lip and eyebrow. Surface-electromyography (EMG) of the left levator labii and frontalis muscles showed rhythmic bursting (duration: 150-450 ms; frequency: 1-3 Hz). Electroencephalographic (EEG)-polygraphic recordings and burst-locked EEG averaging failed to show any consistent EEG activity preceding the EMG bursts. Study of the blink reflex, somatosensory and motor-evoked potentials showed findings consistent with pontine pathology. Segmental facial myoclonus, although extremely rare in children, must be differentiated from several other paroxysmal motor manifestations associated with structural lesions involving the brain stem. Segmental facial myoclonus stem-Structural lesion.     

Belly dance syndrome due to spinal myoclonus.

We report on a case of spinal myoclonus resembling a belly dance syndrome.     

Familial syndrome of deafness, myoclonus, and cerebellar ataxia

We report a case of identical twins with progressive sensorineural hearing loss, myoclonus, intention tremor, and ataxia. The involved member of the family may suggest of autosomal dominant transmission with variable penetrance.     

Acetazolamide improves action myoclonus in Ramsay Hunt syndrome.

The myoclonus of two patients with Ramsay Hunt syndrome was only partially controlled under treatment with clonazepam, sodium valproate, primidone, and piracetam. Acetazolamide (200 mg daily) was added to these drugs, resulting in a dramatic improvement. Placebo substitution (one patient) and withdrawal of acetazolamide in the other patient resulted in marked aggravation of the myoclonus. The mechanism of action of acetazolamide in myoclonus is unknown. Acetazolamide may be an additional therapeutic possibility for patients with severe action myoclonus.     

Cortical myoclonus in angelman syndrome

Angelman syndrome (AS) results from lack of genetic contribution from maternal chromosome 15q11–13. This region encompasses three GABA_A receptor subunit genes (β3, α5, and γ3). The characteristic phenotype of AS is severe mental retardation, ataxic gait, tremulousness, and jerky movements. We studied the movement disorder in 11 AS patients, aged 3 to 28 years. Two patients had paternal uniparental disomy for chromosome 15, 8 had a <3 Mb deletion, and 1 had a microdeletion involving loci D15S10, D15S113, and GABRB3. All patients exhibited quasicontinuous rhythmic myoclonus mainly involving hands and face, accompained by rhythmic 5- to 10-Hz electroencephalographic (EEG) activity. Electromyographic bursts lasted 35 ± 13 msec and had a frequency of 11 ± 2.4 Hz. Burst-locked EEG averaging in 5 patients, generated a premyoclonus transient preceding the burst by 19 ± 5 msec. A cortical spread pattern of myoclonic cortical activity was observed. Seven patients also demonstrated myoclonic seizures. No giant somatosensory evoked potentials or C-reflex were observed. The silent period following motor evoked potentials was shortened by 70%, indicating motor cortex hyperexcitability. Treatment with piracetam in 5 patients significantly improved myoclonus. We conclude that spontaneous, rhythmic, fast-bursting cortical myoclonus is a prominent feature of AS.     

Segmental rigidity and spinal myoclonus as a paraneoplastic syndrome.

A 68 year old woman is described with persisting muscular rigidity of the left lower leg together with transient myoclonic jerking in the left quadriceps muscle. Six weeks after onset a small cell carcinoma of the lung became manifest. With radiotherapy and chemotherapy complete remission was achieved. Segmental muscular spasm improved at the same time. Necropsy revealed loss and degeneration of alpha-motor neuron cells at one side of the anterior horn of the lumbar enlargement. This case may represent another manifestation of paraneoplastic subacute motor neuronopathy.     

Surgical treatment of myoclonus dystonia syndrome

Myoclonus dystonia (M‐D) syndrome is a heritable movement disorder characterized by myoclonic jerks and dystonia primarily of the upper extremities. M‐D remains poorly responsive to pharmacological treatment. Emerging reports suggest good response to DBS of the internal globus pallidus (GPi) and ventral intermediate nucleus (VIM) of the thalamus. This study aimed to appraise the value of these two DBS targets by evaluating reports available in the literature. A systematic search of published case reports and case series was performed on Medline and Embase. Responses to DBS were evaluated. Myoclonus was assessed with the Unified Myoclonus Rating Scale (UMRS) and dystonia by the Burke‐Fahn‐Marsden dystonia rating scale (BFMDRS). The primary outcome of interest was the relative improvements noted with GPi, compared to VIM stimulation. A total of 17 publications yielded 40 unique cases, with mean follow‐up of 27.2 months. All patients demonstrated improvements in myoclonus scores, with 93.5% showing at least a 50% improvement in UMRS. The mean improvement in myoclonus scores was 72.6%. In contrast, dystonia scores were improved in 87.9% of patients, with 72.7% reporting at least a 50% improvement in BFMDRS. The mean improvement in dystonia scores was 52.6%. Improvements in myoclonus scores were similar for both GPi (75.7%) and VIM (70.4%; P = 0.27). However, the improvements in dystonia scores were greater with GPi (60.2%), compared to VIM (33.3%; P = 0.03). Although both targets achieve similar improvements in myoclonus, GPi stimulation may be a preferred target because it may achieve greater improvements in dystonia, compared to VIM stimulation. © 2013 Movement Disorder Society     

Cortical reflex myoclonus in rett syndrome

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 premyclonus 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.     

Reticular reflex myoclonus: a physiological type of human post-hypoxic myoclonus.

A patient with post-hypoxic myoclonus, sensitive to therapy with 5-hydroxytryptophan and clonazepam, was subjected to detailed electrophysiological investigation. Brief generalised jerks followed the critical stimulus of muscle stretch. The electroencephalogram showed generalised spikes that were associated with, but not time locked to, the myoclonus. The cranial nerve nuclei were activated upward. Analysis of the findings suggests that the mechanism of the myoclonus is hyperactivity of a reflex mediated in the reticular formation of the medulla oblongata.     

The Ramsay Hunt syndrome revisited: Mediterranean myoclonus versus mitochondrial encephalomyopathy with ragged-red fibers and Baltic myoclonus

Among progressive myoclonus epilepsies (PME), the nosography of the Ramsay Hunt syndrome (RHS) has been much debated. The authors report on a homogeneous group of 43 patients originating from around the western Mediterranean, with a large number of northern African subjects, who were followed up for a mean period of 11.6 years. Onset is between 6 and 17 years (mean: 11.2) and the transmission appears to be recessive. The clinical features include: action myoclonus, generalized epileptic seizures, mild cerebellar signs and lack of dementia. EEG features include normal background activity, spontaneous fast generalized spike-wave discharges, photosensitivity, lack of activation during nREM sleep and vertex/rolandic spikes during REM sleep. The prognosis is variable, even within families, but the progression seems to be slow in a majority of patients. This condition can be distinguished from mitochondrial encephalomyopathy and is less severe than Baltic myoclonus. The authors propose that this form of PME, formerly reported as RHS, be more properly described as Mediterranean myoclonus.     

Postanoxic action myoclonus (Lance-Adams syndrome) responding to valproate.

A patient with postanoxic action myoclonus (Lance-Adams syndrome) was severely disabled with this movement disorder. Valproate sodium was administered orally, with complete resolution of the myoclonus. This favorable response has been maintained for two years. Excessive yawning, the only side effect encountered, was dose related and was abolished with the addition of pimozide to the drug regimen.     

Auricular myoclonus.

We describe a young man with a two and a half year history of idiopathic irregular contractions of an antitragicus muscle in the absence of a more generalized movement disorder. These contractions persisted in sleep and could not be replicated voluntarily. Because proximal nerve block temporarily eliminated the movements and complex hand movements reduced their amplitude and frequency, we suspect a central generator. However, these movements were not associated with any known pathologic condition.