Search

Background: Abnormal sensory processing, including temporal discrimination threshold, has been described in various dystonic syndromes., Objective: To investigate visual sensory processing in DYT-SGCE and identify its structural correlates., Methods: DYT-SGCE patients without DBS (DYT-SGCE-non-DBS) and with DBS (DYT-SGCE-DBS) were compared to healthy volunteers in three tasks: a temporal discrimination threshold, a movement orientation discrimination, and movement speed discrimination. Response times attributed to accumulation of sensory visual information were computationally modelized, with μ parameter indicating sensory mean growth rate. We also identified the structural correlates of behavioral performance for temporal discrimination threshold., Results: Twenty-four DYT-SGCE-non-DBS, 13 DYT-SGCE-DBS, and 25 healthy volunteers were included in the study. In DYT-SGCE-DBS, the discrimination threshold was higher in the temporal discrimination threshold (P = 0.024), with no difference among the groups in other tasks. The sensory mean growth rate (μ) was lower in DYT-SGCE in all three tasks (P < 0.01), reflecting a slower rate of sensory accumulation for the visual information in these patients independent of DBS. Structural imaging analysis showed a thicker left primary visual cortex (P = 0.001) in DYT-SGCE-non-DBS compared to healthy volunteers, which also correlated with lower μ in temporal discrimination threshold (P = 0.029). In DYT-SGCE-non-DBS, myoclonus severity also correlated with a lower μ in the temporal discrimination threshold task (P = 0.048) and with thicker V1 on the left (P = 0.022)., Conclusion: In DYT-SGCE, we showed an alteration of the visual sensory processing in the temporal discrimination threshold that correlated with myoclonus severity and structural changes in the primary visual cortex. © 2019 International Parkinson and Movement Disorder Society., (© 2019 International Parkinson and Movement Disorder Society.)

The putative involvement of the cerebellum in the pathogenesis of cortical myoclonic syndromes has been long hypothesized, as neuropathological changes in patients with cortical myoclonus have most commonly been found in the cerebellum rather than in the suspected culprit, the primary somatosensory cortex. A model of increased cortical excitability due to loss of cerebellar inhibitory control via cerebello-thalamo-cortical connections has been proposed, but evidence remains equivocal. Here, we explore this hypothesis by examining syndromes that present with cortical myoclonus and ataxia. We first describe common clinical characteristics and underlying neuropathology. We critically view information on cerebellar physiology with regard to motorcortical output and compare findings between hypothesized and reported neurophysiological changes in conditions with cortical myoclonus and ataxia. We synthesize knowledge and focus on neurochemical changes in these conditions. Finally, we propose that the combination of alterations in inhibitory neurotransmission and the presence of cerebellar pathology are important elements in the pathogenesis of cortical myoclonus., (© 2014 International Parkinson and Movement Disorder Society.)

Background: We report 3 patients with typical clinical and electrophysiological characteristics of propriospinal myoclonus propagating from a thoracic spine generator., Methods: In these patients, the pattern of recruitment of long-latency electromyographic reflexes in abdominal muscles was studied in response to various stimuli., Results: Abdominal reflex latency varied from 60 to 140 ms depending on stimulus location. Latency increased from magnetic stimulation of the thoracic spine to electrical stimulation of the supraorbital nerve, electrical stimulation of the median nerve, and magnetic stimulation of the motor cortex., Conclusions: Long-latency abdominal reflex jerks are probably controlled by the brain stem to propriospinal system projections in patients with propriospinal myoclonus. The stereotyped pattern of recruitment of these reflexes could be of clinical utility to differentiate organic propriospinal myoclonus from psychogenic or mimicked jerks., (Copyright © 2011 Movement Disorder Society.)

The ability to understand how Parkinson's disease neurodegeneration leads to cortical dysfunction will be critical for developing therapeutic advances in Parkinson's disease dementia. The overall purpose of this project was to study the small-amplitude cortical myoclonus in Parkinson's disease as an in vivo model of focal cortical dysfunction secondary to Parkinson's disease neurodegeneration. The objectives were to test the hypothesis that cortical myoclonus in Parkinson's disease is linked to abnormal levels of α-synuclein in the primary motor cortex and to define its relationship to various biochemical, clinical, and pathological measures. The primary motor cortex was evaluated for 11 Parkinson's disease subjects with and 8 without electrophysiologically confirmed cortical myoclonus (the Parkinson's disease + myoclonus group and the Parkinson's disease group, respectively) who had premortem movement and cognitive testing. Similarly assessed 9 controls were used for comparison. Measurements for α-synuclein, Aβ-42 peptide, and other biochemical measures were made in the primary motor cortex. A 36% increase in α-synuclein was found in the motor cortex of Parkinson's disease + myoclonus cases when compared with Parkinson's disease without myoclonus. This occurred without significant differences in insoluble α-synuclein, phosphorylated to total α-synuclein ratio, or Aβ-42 peptide levels. Higher total motor cortex α-synuclein levels significantly correlated with the presence of cortical myoclonus but did not correlate with multiple clinical or pathological findings. These results suggest an association between elevated α-synuclein and the dysfunctional physiology arising from the motor cortex in Parkinson's disease + myoclonus cases. Alzheimer's disease pathology was not associated with cortical myoclonus in Parkinson's disease. Cortical myoclonus arising from the motor cortex is a model to study cortical dysfunction in Parkinson's disease., (Copyright © 2011 Movement Disorder Society.)

Background: Lewy body syndromes (mainly Parkinson's disease and dementia with Lewy bodies) share many clinical features and usually have a slowly progressive course. Some patients may show rapid symptoms progression., Objective: To evaluate clinical and neuropathological features of patients with a rapidly progressive diffuse Lewy Body disease., Methods: Review clinical records and pathological findings of 6 cases with diffuse Lewy Body disease and rapid disease progression (less than 18 months before death)., Results: Mean age at disease onset was 72.5 years, and mean disease duration was 9 months. Onset consisted of delirium in 3 patients and rapidly progressive dementia in the other three. All cases presented visual hallucinations and delusions; cognitive symptoms were fluctuating in two, parkinsonism occurred in four, and myoclonus in three. Brain MRI did not show cortical or basal ganglia hyperintensities. Periodic sharp waves were absent on EEG. 14.3.3 protein in CSF was negative. Myocardial (123) I-metaiodo-benzyl-guanidine SPECT showed marked reduction in tracer uptake in the 2 patients tested. Neuropathological studies did not identify any particular feature that could differentiate rapidly progressive diffuse Lewy body disease from classical diffuse Lewy body disease., Conclusions: Diffuse Lewy body disease is a possible cause of rapidly progressive dementia and should be included in the differential diagnosis of confusional states of undetermined cause. In patients with rapidly progressive dementia, the presence of fluctuating cognition, parkinsonism, hallucinations, delusions, or severe dysautonomia, should raise the suspicion of diffuse Lewy body disease. Neuroimaging studies such as (123) I-metaiodo-benzyl-guanidine myocardial scintigraphy may support the clinical diagnosis of diffuse Lewy body disease. © 2011 Movement Disorder Society., (Copyright © 2011 Movement Disorder Society.)

This review examines some of the advances in understanding myoclonus over the last 25 years. The classification of myoclonus into cortical, brainstem, and spinal forms has been consolidated, each with distinctive clinical characteristics and physiological mechanisms. New genetic causes of myoclonus have been identified, and the molecular basis of several of these conditions has been discovered. It is increasingly apparent that disease of the cerebellum is particularly important in the genesis of cortical reflex myoclonus. However, the precise mechanism and origin of myoclonus in many situations remain uncertain. Effective treatment of myoclonus remains limited, and the challenge lies ahead to develop more therapeutic options., (Copyright © 2011 Movement Disorder Society.)

Background: Abnormally enhanced cortical rhythmic activities have been reported in patients with cortical myoclonus. We recently reported a new triad-conditioning transcranial magnetic stimulation (TMS) method to detect the intrinsic rhythms of the primary motor cortex (M1). Triad-conditioning TMS revealed a 40-Hz intrinsic rhythm of M1 in normal subjects. In this investigation, we study the motor cortical facilitation induced by rhythmic triple TMS pulses (triad-conditioning TMS) in patients with cortical myoclonus., Methods: Subjects were 7 patients with cortical myoclonus (28-74 years old) and 13 healthy volunteers (30-71 years old). Three conditioning stimuli over M1 at the intensity of 110% active motor threshold preceded the test TMS at various interstimulus intervals corresponding to 10-200 Hz. The resulting amplitudes of conditioned motor evoked potentials recorded from the contralateral hand muscle were compared with those evoked by the test stimulus alone., Results: The facilitation at 25 ms (40 Hz) observed in normal subjects was absent in patients with cortical myoclonus. Instead, triad-conditioning TMS induced facilitation at a 40 ms interval (25 Hz) in cortical myoclonus., Discussions: This change in the timing of facilitation may be explained by a shift of the most preferential intrinsic rhythm of M1, or by some dysfunction in the interneuronal network in cortical myoclonus., (Copyright © 2011 Movement Disorder Society.)

Spinal Myoclonus (SM) is characterized by brief and sudden movements caused by the activation of muscles belonging to adjacent spinal myotomes. Recent reports have indicated that "typical" clinical and electrophysiological features of SM can be mimicked voluntarily. A useful tool that can distinguish between organic and psychogenic jerks is the detection of a Bereitschaftspotential (BP). In this study, we looked for evidence of a BP in a cohort of patients with idiopathic SM. A clinical and neurophysiological assessment of 20 patients affected by idiopathic SM was performed. A video EEG-EMG multichannel recording was performed in each patient to detect BP. An expert neurophysiologist (PB) reviewed the BP recordings and divided them into those showing a definite, possible, and no BP. A clinical assessment of the videoed movements was performed by two neurologists expert in movement disorders (KB and MJE) who indicated if the movements were compatible with organic or psychogenic myoclonus. A definite or possible BP was recorded in 15 out of 20 patients. Clinical raters agreed in their clinical opinion on 15 patients (75%). All patients where both raters agreed the movements appeared to be organic had definite or possible BP. BP are commonly seen in patients with idiopathic SM. There is discordance between clinicians in their clinical rating of SM as organic or psychogenic, but even in those patients where movements appear clinically to be organic, a BP is commonly detected, indicating that the aetiology is psychogenic. This suggests that BP recordings are a useful adjunct to clinical assessment in the accurate diagnosis of patients with idiopathic SM., ((c) 2009 Movement Disorder Society.)

We report a case of probable psychogenic propriospinal myoclonus (PSM) in a patient who developed a sudden onset of disabling axial flexor myoclonus following a cosmetic surgical procedure. The electrophysiological findings were consistent with previous reports of PSM. Spontaneous remissions and disappearance of the jerks, sustained for 2 years, following removal of superficial surgical screws support the diagnosis of a psychogenic movement disorder., ((c) 2008 Movement Disorder Society.)

Focal myoclonus of peripheral origin, i.e., peripheral myoclonus (PM), is a rare disorder. Although PM always accompanies a lesion in the peripheral nerve, supplying the affected muscles, its mechanism remains unclear. Here we present a patient with focal myoclonus of the thigh muscles following a traumatic lesion in the femoral nerve. Lumbar spinal anesthesia, as well as local anesthetic block of the femoral nerve, completely abolished the patient's myoclonus temporarily. This movement was remarkably diminished after a surgical exploration of the wound with the removal of fibrous tissue beneath the scar and liberation of the femoral nerve. This case suggests the contribution of a spinal relay mechanism in the development of PM, in addition to the contribution of a nerve lesion., (2007 Movement Disorder Society)

Myoclonic dystonia is considered a form of dystonia. We present the unusual case of a 36-year-old woman with HIV infection, who developed left facial myoclonic dystonia, triggered by eating in the setting of probable progressive multifocal leukoencephalopathy involving the contralateral basal ganglia.

A 64-year-old right-handed woman's right hand and arm developed spontaneous jerks that eventually involved her trunk. As she had some features of parkinsonism, she was treated with carbidopa/levodopa and her myoclonus dramatically improved. The mechanism accounting for this improvement is unknown.

The pathophysiology of myoclonus-dystonia (M-D), an autosomal dominantly inherited movement disorder characterized by myoclonic jerks and dystonic contractions, is largely unknown. In the present study, local field potential (LFP) activities in the globus pallidus internus (GPi) from two genetically proven M-D patients are investigated. Coherence analysis between GPi LFP activity and electromyographic muscle activity (EMG) and synchronization of GPi neuronal activity using event-related spectral perturbation (ERSP) in a go-no-go paradigm were studied. Significant increased coherence in the 3 to 15 Hz frequency band was detected between GPi LFP activity and several muscles, with the LFP leading the muscles. The ERSP analysis revealed synchronization in the 3 to 15 Hz frequency band within the GPi before the imperative cue of the go-no-go task and desynchronization in the same band after the cue. The LFP recordings of the GPi in M-D show that the low-frequency band previously described in dystonia is also involved in the dystonia plus syndrome M-D. The 3 to 15 Hz synchronization in the go-no-go paradigm has not been described previously and may point to the existence of (myoclonus-)dystonia specific oscillatory activity in the GPi.

We report a patient with Creutzfeldt-Jakob disease who presented asymmetric myoclonus. Positive-negative myoclonus was seen only in the right extremities in association with periodic synchronous discharges (PSDs) on the electroencephalogram, although pure positive myoclonus was rarely seen in the left extremities, independently in PSDs. The duration of the silent period recorded in the right-hand muscle produced by transcranial magnetic stimulation was much longer than that in the left-hand muscle or that in normal subjects. Brain MRI diffusion-weighted images showed signal hyperintensities in the putamen and cerebral cortex, including the motor cortex, predominantly on the left side.

A 43-year-old man presented with sporadic, sudden, brief, and involuntary jerks of his left limbs and trunk muscles. The electromyographic recordings showed short-lasting highly synchronized bursts, compatible with myoclonus limited to the left hemibody. Blink reflex, masseter silent period, cortical and spinal magnetic stimulation, somatosensory cortical evoked potentials, and electroencephalogram (EEG) were normal; the EEG back-averaging showed no spikes preceding the myoclonus. Magnetic resonance imaging and magnetic resonance angiography showed the presence of an anomalous nonectasic right vertebral artery compressing the right side of ventral medulla oblongata. We hypothesize that the aberrant right vertebral artery induced abnormal activation of descending motor tracts responsible for the myoclonus., ((c) 2004 Movement Disorder Society.)

The sudden, brief, shock-like, involuntary movements caused by active muscular contractions or inhibitions characterize myoclonus. It is manifested in a wide variety of pathologic conditions affecting the brain, spinal cord, or peripheral nerves, and is thought to be related to neuronal hyperexcitability. The pathology, physiology, and pharmacology of myoclonus are not well understood as a result of the rarity of the disorder in people and the lack of a suitable animal model. Posthypoxic myoclonus is a major myoclonus syndrome which occurs as a result of severe cerebral ischemia/hypoxia. There has been tremendous interest in the development of a suitable animal model that reflects the etiology and clinical pathology of posthypoxic myoclonus. Recently, we have developed a new animal model of posthypoxic myoclonus in which rats were subjected to a mechanically induced cardiac arrest procedure. Herein, we describe the neurochemical, pharmacologic, and pathologic characteristics of this animal model of posthypoxic myoclonus.

Introduction: Cerebral anoxia is fundamental to morbidity and mortality after resuscitation from cardiac arrest. With no proven effective primary therapy for post-anoxic brain injury, the goal of neurologic care are supportive, to provide prognosis and prevention of further complications. With the multifaceted approach using electroencephalography (EEG), somatosensory evoked potentials (SEP), multiunit recordings, behavioral and histologic assessment, we investigated the hyperacute recovery period after resuscitation from cardiac arrest in a rat model to define the value of EEG and SEP in assessing neurologic injury., Methods: Two cohorts of rats were subjected to sham and graded asphyxic-cardiac arrest. EEG was collected during baseline, at injury, and 90 minutes into recovery in the first rat cohort. EEG bursting during the first 90 minutes of recovery was visually analyzed and correlated with the neurologic recovery at 24 hours after injury. The neurologic recovery was assessed using a neurodeficit score (NDS) with 80 as normal and 0 as brain dead. The next rat cohort subjected to asphyxic-cardiac arrest was studied using SEP and multiunit recording in the VPL; brain histologic studies were performed at 4 hours after the asphyxia., Results: The first rat cohort subjected to graded asphyxic-cardiac arrest emerged from EEG isoelectricity by burst-suppression pattern during the first 90 minutes after asphyxia. Six rats in the good outcome group (NDS >60) showed increased frequency of bursting, leading to return of EEG background activity. Six rats with a bad outcome (NDS <60) had low-intensity and persistent bursting without return of EEG background activity within 90 minutes of observation. Visual assessment showed increased EEG peak burst counts during the first 90 minutes of recovery for the rats with a good outcome compared with the rats with a bad outcome. In the second cohort, the rats were subjected to 3 minutes, 5 minutes, and 7 minutes of asphyxia. The N20 recovered to 60% of baseline in all three cases. The recovery profile of VPL is similar to that of cortical N2O for the animal with 3 minutes of asphyxia. However, VPL response is suppressed after 7 minutes of asphyxia leading to a divergence in the rate of recovery of the cortical N20 and VPL response. In both the animals (with mild and intermediate injury) in which the early response in VPL recovered to more than 50% of baseline, the recovery profile was similar to the N20 in cortical evoked potential (EP). The rats were killed 4 hours after asphyxia and the hematoxylin and eosin stain performed on the brains showed evidence of neuronal injury in the thalamic reticular nucleus (TRN) which seemed to correlate with the duration of asphyxia., Conclusion: We present a multimodality assessment of early neurologic recovery following resuscitation from cardiac arrest. The recovery of bursting and high-frequency oscillations may be regulated by interneurons in the TRN. The early selective vulnerability of these interneurons in the TRN may be crucial to the early neurologic recovery as assessed by EP, multiunit recording, EEG, and neurologic behavioral recovery.

We describe a patient with an unusual clinical presentation of progressive multiple cranial nerve palsies, cerebellar ataxia, and palatal tremor (PT) resulting from an unknown etiology. Magnetic resonance imaging showed evidence of hypertrophy of the inferior olivary nuclei, brain stem atrophy, and marked cerebellar atrophy. This combination of progressive multiple cranial nerve palsies, cerebellar ataxia, and PT has never been reported in the literature. We have also reviewed the literature of PT secondary to neurodegenerative causes. In a total of 23 patients, the common causes are sporadic olivopontocerebellar atrophy (OPCA; 22%), Alexander's disease (22%), unknown etiology (43.4%), and occasionally progressive supranuclear palsy (4.3%) and spinocerebellar degeneration (4.3%). Most patients present with progressive cerebellar ataxia and approximately two thirds of them have rhythmic tremors elsewhere. Ear clicks are observed in 13% and evidence of hypertrophy of the inferior olivary nucleus in 25% of the patients. The common neurodegenerative causes of PT are OPCA/multiple system atrophy, Alexander's disease, and, in most of them, the result of an unknown cause.

We report the electrophysiologic findings of myoclonus in a patient with Huntington's disease (HD). This patient was studied postoperatively after a bilateral fetal cell transplant in his striatum. Incomplete transient improvement was seen in the myoclonus, followed by gradual deterioration. The myoclonus itself had a cortical correlate and was associated with an enlarged somatosensory evoked potential (SEP), consistent with the presence of cortical reflex myoclonus. An enlarged SEP has not been previously reported in myoclonus associated with HD. The postulated mechanisms for myoclonus, when it occurs in HD, have differed in the literature. The reason for the transient improvement of the myoclonus following transplantation is unclear, but this case raises the possibility that basal ganglia circuits may modulate cortical myoclonic activity.

Focal and segmental, but not generalized, myoclonus have been described with human immunodeficiency virus (HIV) infection. We describe three patients with generalized myoclonus and acquired immunodeficiency syndrome (AIDS) dementia complex. In each, myoclonus persisted until death, invariably after a course of a few months. In two patients, myoclonus was elicited by sudden auditory stimuli and resembled a startle response. This form of myoclonus may be subcortical in origin. We suggest that the AIDS dementia complex be included among the causes of myoclonic dementia.

The short-latency reflex myoclonus that appears to be characteristic of cortical-basal ganglionic degeneration (CBGD) was investigated in two patients. Stimulating the digital nerves of the middle finger caused exaggerated reflex activity in the first dorsal interosseus (FDI) muscle of that hand with a latency of 46-51 ms. Magnetic stimulation over the contralateral cortex, delivered 25 ms after the digital nerve stimulus, resulted in greater than expected facilitation of FDI, implying spatial summation. Poststimulus time histograms (PSTH) of individual FDI motor units indicated that this spatial summation was occurring "upstream" from the motoneurons. It is argued that this occurs at the motor cortex. Magnetic stimulation over the cortex in normal subjects results in short-latency facilitation of the contralateral motoneurons followed by inhibition. This inhibition was less in the patients with CBGD. It is argued that this results from the loss of an intrinsic cortical and corticothalamic inhibitory mechanism.

We describe three patients with Huntington's disease, from two families, in whom myoclonus was the predominant clinical feature. The diagnosis was confirmed at autopsy in two cases and by DNA analysis in all three. These patients all presented before the age of 30 years and were the offspring of affected fathers. Neurophysiological studies documented generalised and multifocal action myoclonus of cortical origin that was strikingly stimulus sensitive, without enlargement of the cortical somatosensory evoked potential. The myoclonus improved with piracetam therapy in one patient and a combination of sodium valproate and clonazepam in the other two. Cortical reflex myoclonus is a rare but disabling component of the complex movement disorder of Huntington's disease, which may lead to substantial diagnostic difficulties.