A novel exaggerated "spino-bulbo-spinal like" reflex of lower brainstem origin.

BACKGROUND: Many different oligosynaptic reflexes are known to originate in the lower brainstem which share phenomenological and neurophysiological similarities. OBJECTIVE: To evaluate and discuss the differences and aberrancies among these reflexes, which are hard to discern clinically using neurophysiological investigations with the help of a case report. METHODS: We describe the clinical and neurophysiological assessment of a young man who had a childhood history of opsoclonus-myoclonus syndrome with residual mild ataxia and myoclonic jerks in the distal extremities presenting with subacute onset total body jerks sensitive to sound and touch (in a limited dermatomal distribution), refractory to medications. RESULTS: Based on clinical characteristics and insights gained from neurophysiological testing we could identify a novel reflex of caudal brainstem origin. CONCLUSIONS: The reflex described is likely an exaggerated normal reflex, likely triggered by a dolichoectatic vertebral arterial compression and shares characteristics of different reflexes known to originate in caudal brainstem, which subserve distinctive roles in human postural control.

Serial MRI findings in brain anoxia leading to Lance-Adams syndrome: a case report.

Although in literature almost 150 patients with Lance-Adams Syndrome (LAS) have been reported, neuroradiological evaluations were often performed in late stages and there is no serial study evaluating LAS from early stages. We herein report a serial neuroimaging study demonstrating early and transient involvement of cerebellum and thalami in a LAS patient. We may hypothesize that a transient cerebral hypoxia provoked a permanent synaptic rearrangements of the neuronal networks involved in the pathogenesis of post-hypoxic myoclonus in our patient.

Thalamic deep brain stimulation for the treatment of action myoclonus caused by perinatal anoxia.

BACKGROUND: Perinatal anoxia rarely causes myoclonus as the main neurologic abnormality. The exact neuronal mechanism underlying myoclonus induced by perinatal anoxia remains unknown. Some studies have indicated that the development of involuntary movements may be related to the maturation of the thalamus after birth. OBJECTIVES AND METHODS: Here, we describe the first case of a patient who developed action myoclonus after experiencing perinatal anoxia and was successfully treated by chronic deep brain stimulation (DBS) of the thalamus (thalamic DBS). RESULTS AND CONCLUSION: The effectiveness of chronic thalamic DBS in this patient supports the concept of involvement of the thalamus in post-perinatal anoxic myoclonus.

The metabolic topography of posthypoxic myoclonus.

Posthypoxic myoclonus (PHM) is a syndrome of action and intention myoclonus that occurs in some patients who survive a cardiac arrest. Using PET and statistical parametric mapping, the authors observed a significant bilateral increase in glucose metabolism in the ventrolateral thalamus and pontine tegmentum in patients relative to controls. Interventions such as deep brain stimulation that interrupt networks that involve these structures may be useful in patients with severe PHM.

Reduction of cortical myoclonus-related epileptic activity following slow-frequency rTMS.

In a drug-resistant epilepsy patient with continuous forearm/hand positive myoclonia due to a focal cortical dysplasia of the right motor cortex, cortical jerk-related and electromyographic activity were recorded for 15 min before and after 1 Hz rTMS (15 min, 10% below the resting excitability threshold) of the right motor cortex. A stable negative cortical spike, time-locked with contralateral muscle jerks (60 > 100 microV), was detected only at perirolandic electrodes (maximal amplitudes: block 1 = 21.3 microV, block 2 = 22 microV, block 3 = 25.9 microV). After rTMS, only 20 muscle jerks accomplished the criterion of > 100 microV; blind back-averaging of these disclosed a topographically similar cortical spike, but with amplitude reduced by at least 50% (11.2 microV). This represents in vivo evidence of the possibility to selectively modulate the activity of an epileptic focus by intervening with local low-frequency rTMS.

Posthypoxic myoclonus animal models.

The animal model presented here resembles several of the key features of human myoclonus. Further study of the neuropathology and pharmacology of this animal model will hopefully increase our knowledge of the brain structures and systems affected in this disease and permit testing of therapeutic agents for the significant number of patients who do not respond to current treatments.

Complex movement disorders following bilateral paramedian thalamic and bilateral cerebellar infarcts.

Complex movement disorders (CMD; including tremor, dystonias, choreoatheosis, and myoclonus) following infarcts in the posterior and posterolateral thalamic nuclei have been reported. This case of a 59-year-old man who developed CMD following bilateral paramedian and bilateral cerebellar infarcts illustrates the lack of anatomic specificity and the diverse pathophysiology which may underlie CMD.

Irregular jerky tremor, myoclonus, and thalamus: a study using low-frequency stimulation.

High-frequency thalamic stimulation alleviates tremor in Parkinson's disease (PD) and essential tremor (ET). The origin of thalamic myoclonus is unexplained and the effects of low-frequency thalamic stimulation on movement control are still unknown. We studied the effects of stimulation at a low frequency of 15 Hz in five drug-free patients (3 PD, 2 ET) 6 months after thalamic implantation of quadripolar electrodes (unilateral in four patients, bilateral in one patient). Clinical, electrophysiological, and videotaped assessment, using a monopolar 15 Hz frequency (3 V, 90 micros) stimulation current applied simultaneously through two adjacent contacts of the electrode, was performed. We observed myoclonus and irregular jerky tremor in the upper limb contralateral to the site of stimulation. The jerks lasted less than 200 ms, were irregular and not synchronous with stimulation, were superimposed on rest or postural tremor, and increased in response to tactile, proprioceptive, or vibratory stimuli. The fact that this complex movement disorder can be induced by low-frequency stimulation in the ventral intermediate nucleus (Vim) of the thalamus suggests that it results, at least partly, from dysfunction of the Vim and possibly adjacent nuclei of the thalamus.

Facial dyskinesia induced by auditory stimulation: a report of four cases.

INTRODUCTION: The Vibroacoustic Disease (VAD) is an occupational pathology induced by long-term (>10 yr) exposure to large pressure amplitude (> or = 90 dB SPL) and low frequency (< or = 500 Hz) noise. During studies contributing to the characterization of VAD, abnormal facial movements induced by repetitive auditory stimuli were observed in one individual employed as an aeronautical mechanic. The goal of this study was to investigate the existence of movement disorders triggered by auditory stimuli in a group of VAD-diagnosed patients. METHODS: Sixty VAD patients received auditory and median nerve stimulation. Simultaneously, EEG monitoring was performed. RESULTS: Abnormal myoclonus movements were triggered by auditory stimuli in four patients. EEG recordings were normal in all 60 patients. Stimulation of the median nerves did not trigger any abnormal movements. CONCLUSION: These data suggest that this facial dyskinesia has a subcortical origin.

Traumatic spinal myoclonus.

A 24-yr-old woman suffering from traumatic spinal myoclonus which occurred after a diving injury, and which had not responded to pharmacotherapy, apparently resolved after treatment by manipulation of the spine. Mechanisms of the etiology of myoclonus are discussed, and theoretical mechanisms for the use of manipulative procedures in the management of traumatic spinal myoclonus are advanced.

Toxic myoclonus.

Several toxins produce encephalopathies in which myoclonus can be a prominent feature. These include intoxications with bismuth, methyl bromide, cooking oil containing anilines, and tetraethyl lead. The clinical features in many cases resemble the action myoclonus syndrome of posthypoxic encephalopathy.

Induction of acute myoclonic encephalopathy in hamsters by subacute sclerosing panencephalitis virus.

Myoclonus is a characteristic neurological sign of subacute sclerosing panencephalitis (SSPE). Attempts were made to induce myoclonus in a large proportion of hamsters with a cell-associated strain of SSPE virus (the Biken strain) and thereby to establish an experimental model for study of the mechanism of development of this condition. When injected intracerebrally, Biken virus induced myoclonus within two to 14 days in 84% of the three- to nine-week-old hamsters tested. Electroencephalographic traces showed a periodic and synchronous discharge consisting of high-voltage slow waves and spikes that appeared coincidentally with myoclonus. Neurons in the cortex and thalamus of the affected animals had severely degenerated cytoplasm. Inflammatory changes, such as perivascular cuffing or infiltration of mononuclear cells, were not detected. Staining with immunoperoxidase revealed measles viral antigens in the cytoplasm and dendrites of the affected neurons. SSPE virus with the same properties as the parent virus was recovered from brain cells of sick animals by cocultivation with Vero cells.

[Benzodiazepine physical dependence. 6 cases (author's transl)]. / Dépendance physique aux benzodiazépines. 6 observations.

The symptoms include, by ascending order of severity: nightmares and insomnia, nausea and vomiting, muscular weakness or tremor, postural hypotension, hyperthermia, muscle twitching, convulsions, confusional state or psychosis. Prominent features are the late onset of these symptoms, several days after treatment has been discontinued, and the sometimes difficult diagnosis, since patients are usually unaware of their dependence on these drugs. Reinstituting benzodiazepine treatment, then withdrawing it progressively are the best curative measures. Prevention is easy if treatment is gradually rather than abruptly withdrawn in all patients who receive the compound in high dosage for more than one month.