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PubMed1994

The myoclonus in corticobasal degeneration. Evidence for two forms of cortical reflex myoclonus.

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.

Adult↗

PubMed1986

p,p'-DDT-induced myoclonus in the rat and its application as an animal model of 5-HT-sensitive action myoclonus.

p,p'-DDT-induced myoclonus in mice has been proposed as a model of stimulus-sensitive action myoclonus responsive to L-5-HTP and clonazepam treatment. However, we have been unable to confirm the ability of clonazepam to reduce myoclonus induced by p,p'-DDT in the rat. A detailed pharmacological, biochemical, and physiological investigation in the latter species shows p,p'-DDT-induced myoclonus not to resemble stimulus-sensitive action myoclonus occurring in humans. Precursors of 5-HT (L-tryptophan and L-5-HTP) reduced the intensity of myoclonus, but the 5-HT agonists quipazine and Org 6582 did not. 5-HT antagonists (methergoline, methysergide, and cinanserin) did not potentiate myoclonus induced by p,p'-DDT. In contrast, administration of MAOIs (pargyline, nialamide, and tranylcypromine) markedly attenuated the myoclonus. No observable changes in cerebral 5-HT biochemical parameters occurred at the onset of myoclonus, although brain tryptophan and 5-HIAA were increased following periods of prolonged myoclonus. Electrophysiological analysis of p,p'-DDT-induced myoclonus in the rat revealed changes in EEG and EMG activity that were different from those observed in human reticular reflex myoclonus. In conclusion, in contrast to the mouse, myoclonus induced by p,p'-DDT in the rat does not appear to be a suitable model of 5-HT-sensitive action myoclonus in man.

5-Hydroxytryptophan↗

PubMed1982

[Myoclonus induced by some benzodiazepines in the Papio papio. Comparison with myoclonus induced by intermittent light stimulation (author's transl)].

Papio papio may show two different kinds of myoclonus. A first type corresponds to myoclonus induced by photic stimulation (25 Hz). This type is always preceded by paroxysmal discharges. Another type of myoclonus may be induced, or at least facilitated, by some benzodiazepines, especially lorazepam and, to a lesser extent, diazepam. This type is neither preceded nor accompanied by paroxysmal discharges. A single injection of lorazepam (1 mg/kg i.v.) blocks the first type of myoclonus but favors the appearance of the second. However, these effects do not follow the same evolution; while myoclonus induced by photic stimulation disappears immediately after the injection, benzodiazepine-induced myoclonus appears only 10-15 min. Furthermore, whereas the former reappears after 150-210 min, the latter may persist for a longer time (up to 1 h). A preliminary pharmacologic study of benzodiazepine-induced myoclonus indicates that drugs increasing brain GABA level block this type of myoclonus. The possible reticular origin of benzodiazepine-induced myoclonus is suggested.

Allylglycine↗

PubMedDate not supplied

[A case of spinal segmental myoclonus and propriospinal myoclonus: a neuroelectrophysiologic analysis].

A 37-year-old male patient with spinal segmental myoclonus and propriospinal myoclonus was described. He was admitted to our hospital because of paroxysmal axial myoclonus, which first appeared one month before. He denied any significant accident such as trauma or fever. Apart from myoclonus, no abnormal findings were observed by physical and neurological examinations, routine laboratory investigations and MRI of the cervical and thoracic spinal cords. The myoclonus consisted of continuous rhythmic contractions of the bilateral thoracal and abdominal muscles. Its frequency was approximately 0.3Hz. The clinical findings were typical of spinal segmental myoclonus. In addition, the myoclonus started in the thoracal muscles and frequently spread up to the neck muscles and down to the leg muscles. The myoclonus disappeared in sleep. Polymyography revealed the following findings: (1) The jerks were found on the bilateral axial muscles including sternocleidomastoid, biceps, triceps, pectoralis major, abdominal muscles and quadriceps. (2) Homologous muscles were activated synchronously. (3) The duration of bursts was variable ranging 100 to 400msec. (4) The jerks in the pectoralis muscle preceded those in other muscles. The latencies of the jerks in the other muscles increased with their distance from pectoralis, based on the linear regression analysis of the onset of jerks in the various muscles. (5) The jerks were induced by tapping or electrical stimulation anywhere on the body including the face, but not by flash or sound. From the above polymyographical findings, the myoclonus seems to originate in the T3 spinal cord and slowly up and down the spinal cord at 0.6-1.6 m/sec, suggesting that it is mediated by the propriospinal tract.

Adult↗

PubMed1992

[Rhythmic skeletal myoclonus without palatal myoclonus].

We reported a case of 89-year-old woman showing rhythmic skeletal myoclonus mainly on the right upper limb. This myoclonus appeared five days after the cerebral infarction. It was seen constantly both at rest and in posture, and decreased during voluntary movement. When the patient was under emotional stress, it spread to the submandibular, neck and trunks of upper limb. During sleep, this movement completely disappeared. There was no myoclonus in palato-pharyngo-laryngo-oculo-diaphragmatic muscle group. In the examination of the surface electromyography, the movement was not reciprocal between extensor and flexor muscles, and its cycle was about 3.5 Hz. It was different from the intention tremor because it did not increase during the movement phase on the finger nose test. The examination of MRI revealed a small infarction including right dentate nucleus and right superior cerebellar peduncle, and from which an infarction of the superior cerebellar artery territory was considered. Only a few cases of rhythmic skeletal myoclonus without palatal myoclonus have been reported in the literature. All of these cases had small infarction of the same region as the above case. Their myoclonus began 5 to 15 days after the onset of cerebral infarction. These periods were markedly shorter than that of intention tremor and palatal myoclonus. This fact suggest that the rhythmic skeletal myoclonus has a different mechanism from that of the palatal myoclonus.

Aged↗

PubMed1977

Ballistic movement overflow myoclonus a form of essential myoclonus.

The clinical and electrophysiological findings in 2 cases of familial essential myoclonus are presented. The myoclonus was inherited apparently as an autosomal dominant trait, onset was in the first decade of life and the course was benign without the development of other significant neurological deficits. The electroencephalogram was unremarkable. The electromyographic appearance of the myoclonus was 50-100 ms complex bursts, usually occurring alternately in agonists and antagonists, similar to a normal ballistic movement. Muscles throughout the body were activated synchronously. In one of the cases myoclonus occurred at rest, but in both cases the myoclonus could be regularly produced by attempting a rapid movement. The myoclonic activity occurred simultaneously with the appropriate muscle activity which initiated the ballistic movement. It was as if the command to generate a ballistic movement overflowed into an excessive number of muscles. From a review of the literature it was concluded that this physiological mechanism was probably responsible for a definite sub-group of essential myoclonus. The relation of this type of myoclonus to other types of myoclonus and other involuntary movement disorders is discussed.

Adult↗

PubMed1991

Scalp topography of giant SEP and pre-myoclonus spike in cortical reflex myoclonus.

Scalp topography of the giant SEP and the pre-myoclonus spike demonstrated by jerk-locked back averaging was studied by using a computer-assisted evoked potential mapping technique in 5 patients with cortical reflex myoclonus. The initial positive peak of giant SEP was localized to the postcentral region contralateral to the stimulus and was associated with a negative potential field of the same latency at the frontal region in all cases. The main positive peak of pre-myoclonus spike was localized to the postcentral region contralateral to the myoclonus in 4 cases, and maximal at the midline postcentral region extending contralaterally with respect to the myoclonus in 1 case. The postcentral positive peak was associated with a frontal negativity in 2 of the 5 cases. In those 2 cases, the main components of giant SEP and the pre-myoclonus spike showed a similar scalp distribution with respect to the hand which was stimulated or myoclonic jerks were recorded from, although the latter was much smaller and less sharp than the former. These findings support our previous hypothesis that those 2 activities might be generated, at least in part, by common physiological mechanisms. In 3 other cases, however, the postcentral positive peak of the pre-myoclonus spike was not associated with a frontal negativity.

Action Potentials↗

PubMedDate not supplied

Hiccup and apparent myoclonus after hydrocodone: review of the opiate-related hiccup and myoclonus literature.

The author recently encountered a patient with hiccups, intermittently accompanied by apparent focal rhythmic diaphragmatic myoclonus after hydrocodone administration. Review of the literature disclosed a paucity of previous reports of hiccup, but many reports of myoclonus after opiate administration. A wide variety of opiates and routes of administration have been implicated, but high doses and the presence of other agents (antipsychotics, antiemetics, nonsteroidal antiinflammatory agents, antidepressants) may pose special risks. Review of the literature suggests three types of opiate-related myoclonus. Opiate-induced myoclonus (OIM) is often generalized and is either periodic or associated with rigidity. Opiate-induced myoclonus frequently occurs in the context of underlying medical conditions, D2 antagonist coadministration, or other drugs (nonsteroidal anti-inflammatory agents, antidepressants), and usually responds to either naloxone or benzodiazepines. Intrathecal OIM has not been linked to D2 antagonist coadministration or benzodiazepine responsiveness but may be associated with non-steroidal antiinflammatory agents. Opiate withdrawal myoclonus may be stimulus-sensitive, associated with D2 antagonist coadministration, and responsive to benzodiazepines and unresponsive to naloxone. There are several problems in interpreting the literature, and more study is needed. Opiatergic, serotonergic, dopaminergic, and other mechanisms are considered.

Analgesics, Opioid↗

PubMed1993

The cholinergic system-dependent myoclonus of the baboon Papio papio is a reticular reflex myoclonus.

Neurophysiological studies were performed on four Papio papio baboons presenting with nonepileptic myoclonus (a startle response resembling stimulus-sensitive jerk). Investigations of the EEG, back-averaged EEG, and somatosensory evoked potentials revealed the absence of cortical correlates preceding the jerks, and exclusion of cerebral cortex involvement. No long-latency reflexes could be recorded in these animals. The jerks were symmetric when evoked by unilateral stimulation in normal baboons as well as in a split-brain animal. Polymyographic records showed that the first muscle involved during the jerk was the trapezius; other muscles were involved with latencies increasing in both cranial and caudal directions. From these data, nonepileptic myoclonus of baboons can be classified as a reticular reflex myoclonus. The involvement of cranial nerves did not follow the layout of the nuclei in the brainstem, indicating that the jerk is most likely generated as a complete movement. The generating structure is probably under cholinergic control. Finally, the Papio papio baboon, which was already known as a model for cortical myoclonus elicited by intermittent photic stimulation in predisposed animals, can also be considered a model for the study of the reticular reflex myoclonus.

Animals↗

PubMed1999

[A case of stiff-man syndrome with head retraction like reflex myoclonus and jerky myoclonus of bilateral lower extremities which responded well to removal of mediastinal carcinoma].

A 58-year-old male presented with reflex myoclonus and stiffness of the left facial, tongue, shoulder, and lower limbs muscles. Muscle stiffness and gait progressively worsened, leading to frequent falls. Acoustic and cutaneous stimuli of head precipitated reflex myoclonus like head retraction. Cutaneous of lower extremities precipitated jerky myoclonus of bilateral lower extremities. CSF analysis were unremarkable. No anti GAD antibody or anti amphiphysin antibody was detected in the serum and CSF. On surface EMG the spasms initiated with 4-5 short burst discharges at intervals between 59 and 84 ms, followed by a tonic decrescendo activity up to 3 s. After diazepam treatment, stiffness and reflex myoclonus of lower extremities were disappeared and head retraction like reflex myoclonus was improved but remained. CT of the chest revealed a mediastinal tumor. Biopsy of the tumor revealed undifferential carcinoma. The patient further improved after the resection of the tumor. These findings suggest that this stiff-man syndrome may occur as an autoimmune paraneoplastic syndrome of CNS.

Autoimmunity↗

PubMed1990

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.

Adolescent↗

PubMed1988

Postradiation segmental myoclonus selectively inhibited by REM sleep (sleep-wake myoclonus).

A 46-year-old male patient was irradiated following left orchiectomy for seminoma. Three months after radiation, segmental myoclonus appeared involving all skeletal muscle groups up to the level of D10, the area of radiation. Urodynamic testing showed the presence of segmental myoclonus in the urethral sphincter. An around-the-clock 'continuous segmental myoclonus' during sleep and wakefulness with a frequency of 1 c/s and an amplitude of 400 microV selectively inhibited by REM sleep was not found in the literature. This continuous segmental myoclonus caused by a radiation myelopathy at D10-D11 was followed up for 2 years. It was partially controlled by carbamazepine.

Carbamazepine↗

PubMed1990

Generalized reflex myoclonus in a patient with alcohol-sensitive spontaneous myoclonus and an abnormal gait.

A patient with alcohol-sensitive spontaneous, action- and stimulus-sensitive generalized reflex myoclonus is reported. Gait was abnormal but could not be clearly classified as dystonic. No other neurological abnormality was present. The possible relationship between alcohol-sensitive myoclonic dystonia and this case is discussed. Reflex myoclonus may serve as an additional clinical marker in the study of families with alcohol-sensitive myoclonus, dystonia, or both.

Adult↗

PubMed1977

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.

5-Hydroxytryptophan↗

PubMed1979

Uraemic myoclonus: an example of reticular reflex myoclonus?

Two patients are described who developed action, reflex myoclonus during acute renal failure. In both cases the myoclonus was abolished after the intravenous administration of clonazepam. We suggest that the characteristic action myoclonus, which occurs in both acute renal failure and postanoxic encephalopathy, is caused by a disturbance of function in the lower brainstem reticular formation.

Acute Kidney Injury↗

PubMed1999

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.

Humans↗

PubMed1992

[Myoclonus epilepsy associated with ragged-red fibers--report of a patient with negative myoclonus].

A 21-year-old woman, who had no particular familial history, was admitted to our hospital because of hand tremor and gait disturbance. On neurological examination, she showed muscle weakness in the proximal extremities. There was an ataxia on heel-to-shin testing. Action and postural myoclonus involving the extremities were also noted. In addition, with dorsiflexion of the hands, asterixis-like movement was manifested. Pyruvate was 1.0 mg/dl and lactate was 24.1 mg/dl in cerebrospinal fluid. Brain CT scan revealed mild cerebellar atrophy. EEG showed synchronous diffuse slow wave. Median nerve SEPs showed a large N20-P25 component (20 microV). Median nerve C-reflex was not evoked. With dorsiflexion of the hands, the asterixis-like movement was induced with brief cessation of surface EMG activity in the forearm muscles, as shown by the accelerometer trace. Biopsy specimens of the biceps brachii muscle revealed numerous ragged-red fibers. By PCR-RFLP method with use of a mismatched primer, we analyzed mitochondrial DNA extracted from peripheral leukocytes. The A to G mutation at nucleotide position 8,344 in a tRNA(Lys) gene of a mitochondrial genome was detected. In this patient, clonazepam was effective on the asterixis-like movements. From existence of positive myoclonus, giant SEPs and efficacy of clonazepam, we considered this movement to be negative myoclonus. Our study indicated the possibility that such an involuntary movement could be induced by certain posture in patients with MERRF.

Adult↗

PubMed1985

Visual evoked response abnormality in myoclonus epilepsy with large pupils. Occurrence in a family with acorpuscular myoclonus epilepsy.

Flash and pattern evoked responses were recorded from three siblings with myoclonus epilepsy who all had strikingly large pupils in daylight. Comparison with the visual evoked responses (VERs) of 15 normal and eight epileptic control subjects (including one with myoclonus epilepsy but normal pupils) disclosed a substantial reduction of the amplitude of the flash response as compared with the normal pattern response in these three patients. It is suggested that the VER constellation and the pupillary abnormality, together with the normal electroretinogram and diffusely distributed relative scotomas, were due to a ganglion cell loss in the retina.

Adult↗