Myoclonus: an update.

PURPOSE OF REVIEW: Myoclonus, a common hyperkinetic movement disorder, can be disabling for patients. It is important to identify and classify myoclonus correctly to ensure appropriate workup and treatment. While the clinical history, examination, and process of classifying myoclonus remain largely unchanged, new causes and triggers for myoclonus are being elucidated, and new genetic causes have been found. Treatment can be challenging, though preliminary data about new options has been promising. RECENT FINDINGS: In this article, we will briefly outline the process of classifying and treating myoclonus. We will then discuss three specific scenarios where myoclonus has been identified: myoclonus associated with SARS-CoV-2 infections, spinal myoclonus following surgery or anesthesia of the spine, and auricular myoclonus. We will also discuss new genetic findings associated with myoclonus-dystonia, and promising results regarding the use of perampanel in treating myoclonus. SUMMARY: The process of describing unique scenarios associated with myoclonus has helped us build our understanding of the causes, genetic background, expected prognosis, and effective treatment of specific types of myoclonus. We hope that further studies on this topic will help tailor treatment.

Spinal cord stimulation for complex regional pain syndrome type I with spinal myoclonus - a case report and review of literature.

BACKGROUND: Complex regional pain syndrome (CRPS) is a chronic neuropathic painful condition, sometimes associated with spinal myoclonus. For intractable cases spinal cord stimulation is an important modality of treatment but the response of specifically myoclonus to this treatment is not well described. CASE DESCRIPTION: A 40-year old male, had a history of trauma 12 years back since when he had intractable neuropathic pain in his both upper limbs with superimposed severely disabling myoclonic jerks. He had been through multiple treatment failures. We inserted a cervical spinal cord stimulator which led to immediate cessation of myoclonic jerks, with significant improvement in visual analogue score and Oswestry disability index. CONCLUSION: In patients of chronic intractable cervico-brachial pain disorder with superimposed myoclonus, cervical spinal cord stimulation may be effective against the myoclonus as well as the pain.

Middle ear myoclonus: Systematic review of results and complications for various treatment approaches.

OBJECTIVE: To perform a systematic review of the diagnosis and treatment of patients with pulsatile tinnitus secondary to middle ear myoclonus. DATABASES REVIEWED: PubMed, EMBASE, and Scopus. METHODS: A systematic review was performed using standardized methodology. Computerized and manual searches were performed to identify studies of all ages (patients) who had middle ear myoclonus (intervention). All study designs were assessed. Extracted data included demographics, clinical features, duration of followup as well as the diagnosis and reversibility of symptoms with medical or surgical intervention. Studies were included if they included subjects with middle ear myoclonus. Exclusion criteria included letters/commentaries and reviews. RESULTS: Twenty articles representing 115 subjects with middle ear myoclonus were included. The mean age was 29.7 (range 6-67). The follow-up period ranged from 5 weeks to 36 months. Primary treatment consists of medical therapy utilising anxiolytics, antiepileptics, botulinum toxin and surgical treatment involving division of middle ear muscular tendon(s). In total, 60 patients underwent middle ear muscular tenotomies, with division of both stapedius and tensor tympani tendons being the most prevalent (88%). Limitations in the data arose from study design, related comorbidities such as palatal myoclonus, and concomitant drug administration. No study provided any objective criteria to diagnose this condition or evaluate post-treatment outcome. CONCLUSION: Middle ear myoclonus is an entity that is poorly assessed in the literature. There is a lack of consensus regarding the criteria and strategies for both diagnosing and treating this condition. Although level of evidence of current studies remains modest, it is felt that a stepwise approach is deemed best, with therapeutic decisions being made on an individual basis, evaluating each patient's specific circumstances and priorities.

Neurological symptoms improved by hyperbaric oxygen therapy in a post-cardiac arrest patient due to carbon monoxide poisoning: a case report.

Background: Carbon monoxide (CO) poisoning and cardiac arrest can cause neurological complications such as mental deterioration and movement disorders through ischemic brain injury. We report a case in which neurological sequelae after cardiac arrest caused by CO poisoning improved after hyperbaric oxygen (HBO2) therapy. Case report: A 43-year-old male visited the hospital with cardiac arrest due to CO poisoning. He developed neurological sequelae including mental deterioration and myoclonus after recovering spontaneous circulation. Anticonvulsant therapy was used after target temperature management but did not have a positive effect on neurological symptoms. However, after HBO2 therapy the patient's neurological symptoms improved, and he was discharged a month later. Conclusion: HBO2 therapy may be considered when neurological sequelae persist after cardiac arrest due to CO poisoning.

Myoclonus in Patients With Coronavirus Disease 2019: A Multicenter Case Series.

OBJECTIVES: To describe the risk factors for and outcomes after myoclonus in a cohort of patients with coronavirus disease 2019. DESIGN: Multicenter case series. SETTING: Three tertiary care hospitals in Massachusetts, Georgia, and Virginia. PATIENTS: Eight patients with clinical myoclonus in the setting of coronavirus disease 2019. INTERVENTIONS & MEASUREMENTS AND MAIN RESULTS: Outcomes in patients with myoclonus were variable, with one patient who died during the study period and five who were successfully extubated cognitively intact and without focal neurologic deficits. In five cases, the myoclonus completely resolved within 2 days of onset, while in three cases, it persisted for 10 days or longer. Seven patients experienced significant metabolic derangements, hypoxemia, or exposure to sedating medications that may have contributed to the development of myoclonus. One patient presented with encephalopathy and developed prolonged myoclonus in the absence of clear systemic provoking factors. CONCLUSIONS: Our findings suggest that myoclonus may be observed in severe acute respiratory syndrome coronavirus 2 infected patients, even in the absence of hypoxia. This association warrants further evaluation in larger cohorts to determine whether the presence of myoclonus may aid in the assessment of disease severity, neurologic involvement, or prognostication.

Clinical Outcome and Intraoperative Neurophysiology of the Lance-Adams Syndrome Treated with Bilateral Deep Brain Stimulation of the Globus Pallidus Internus: A Case Report and Review of the Literature.

BACKGROUND: The Lance-Adams syndrome (LAS) is a myoclonus syndrome caused by hypoxic-ischemic encephalopathy. LAS cases could be refractory to first-line medications, and the neuronal mechanism underlying LAS pathology remains unknown. OBJECTIVES: To describe a patient with LAS who underwent bilateral globus pallidus internus (GPi) stimulation and discuss the pathophysiology of LAS with intraoperative electrophysiological findings. PATIENTS: A 79-year-old woman presented with a history of cardiopulmonary arrest due to internal carotid artery rupture following carotid endarterectomy after successful cardiopulmonary resuscitation. However, within 1 month, the patient developed sensory stimulation-induced myoclonus in her face and extremities. Because her myoclonic symptoms were refractory to pharmacotherapy, deep brain stimulation of the GPi was performed 1 year after the hypoxic attack. RESULTS: Continuous bilateral GPi stimulation with optimal parameter settings remarkably improved the patient's myoclonic symptoms. At the 2-year follow-up, her Unified Myoclonus Rating Scale score decreased from 90 to 24. In addition, we observed burst firing and interburst pause patterns on intraoperative microelectrode recordings of the bilateral GPi and stimulated this area as the therapeutic target. CONCLUSION: Our results show that impairment in the basal ganglion circuitry might be involved in the pathogenesis of myoclonus in patients with LAS.

[Myoclonus of the middle ear]. / Mioklonus myshts srednego ukha.

The objective of the present study was to overview the foreign literature concerning middle ear myoclonus (MEM) known to be the most common cause of the manifestations of objective tinnitus. The authors reports two typical clinical cases of myoclonus of the middle ear. The present article is aimed at the enhancement of the awareness of the otorhinolaryngologists, audiologists, and neurologists of the condition of interest as a way to promote the further progress in its treatment.

Redefining progressive encephalomyelitis with rigidity and myoclonus after the discovery of antibodies to glycine receptors.

PURPOSE OF REVIEW: This review highlights the recent discovery of antibodies to glycine receptor (GlyR-Ab) and discusses the relationship between these antibodies and neurological disorders. RECENT FINDINGS: Since the initial description in 2008 of antibodies to glycine receptors (GlyR-Abs) in a patient with progressive encephalomyelitis with rigidity and myoclonus (PERM), these antibodies have been found in PERM and in some patients with a variety of stiff person spectrum (SPS) or related disorders. Patients with GlyR-Abs often improve with aggressive immunotherapy, and antibody titres correlate with disease severity. Around 25% of patients have another autoimmune condition and 10-20% have an underlying malignancy. GlyR-Abs bind to extracellular determinants, are mainly Immunoglobulin G1 subclass and induce GlyR internalization in Human embryonic kidney 293 cells, suggesting pathogenicity. The spectrum of neurological disease associated with GlyR-Abs has not been fully characterized, and lower titres may not be syndrome specific, but GlyR-Abs, like antibodies to other neuronal cell-surface antigens, define immunotherapy-responsive disease and are likely to be pathogenic. This distinguishes them from the glutamic acid decarboxylase antibodies that can also be found at high titres in patients with classical stiff person syndrome which is more often chronic and relatively resistant to immunological treatments. SUMMARY: Irrespective of the clinical features, GlyR-Abs are helpful in the diagnosis of patients who very often have a subacute, progressive and life-threatening disorder which shows a favourable response to immunotherapy.

To jerk or not to jerk: A clinical pathophysiology of myoclonus.

Myoclonus is a sudden brief (20-250 ms) contraction (positive myoclonus), or a brief and sudden cessation of tonic muscle (negative myoclonus) inducing a simple jerky movement of body part. Myoclonus could have different origins in almost every part of the nervous system, from the cortex to the peripheral nerve, sharing a large panel of etiologies. It is regarded as the paradigmatic movement disorder causing jerks, although not the sole. This paper aims to depict the clinical and neurophysiological characteristics of myoclonus. It shows how neurophysiological investigations including surface polymyography and methods exploring cortical excitability, namely conventional EEG, EEG - jerk-locked back-averaging, somatosensory evoked potentials and C-reflex studies are required to define the generator of myoclonus in the central nervous system and clearly classify myoclonus as cortical, corticothalamic, subcortical - resulting from lesions or dysfunctions of basal ganglia/reticular system - or spinal. This paper also enlightens other movement disorders that may mimic myoclonus appearances, including psychogenic jerks, simple motor tics, spasms and startle syndromes. Finally, it raises few unresolved questions regarding the propriospinal myoclonus or peripheral myoclonus entities, the role of the cerebellum in myoclonic diseases and the relationship between cortical and epileptic myoclonus.

Movement disorders and stroke.

Stroke may be associated with different types of movement disorders, such as hyperkinetic syndromes (hemichorea-hemiballism, unilateral asterixis, limb-shaking, dystonia, tremor, myoclonus) and hypokinetic syndromes (especially vascular parkinsonism). However, movement disorders are rare and transient in acute stroke and, as a permanent consequence, are more often delayed. While ischemic and hemorrhagic strokes can happen at any level of the frontal-subcortical motor system, they can be explained most of the time by a dysfunction in the basal ganglia motor circuit. However, only brain MRI allows the involved structure(s) to be precisely located, and each syndrome is specific to the type of lesion. Treatment is above all symptomatic. Only limb-shaking syndrome requires urgent surgical treatment because of the low-perfusion hemodynamic state. The functional prognosis depends on the type of movement disorder.

PTG protein depletion rescues malin-deficient Lafora disease in mouse.

Ubiquitin ligases regulate quantities and activities of target proteins, often pleiotropically. The malin ubiquitin E3 ligase is reported to regulate autophagy, the misfolded protein response, microRNA silencing, Wnt signaling, neuronatin-mediated endoplasmic reticulum stress, and the laforin glycogen phosphatase. Malin deficiency causes Lafora disease, pathologically characterized by neurodegeneration and accumulations of malformed glycogen (Lafora bodies). We show that reducing glycogen production in malin-deficient mice by genetically removing PTG, a glycogen synthesis activator protein, nearly completely eliminates Lafora bodies and rescues the neurodegeneration, myoclonus, seizure susceptibility, and behavioral abnormality. Glycogen synthesis downregulation is a potential therapy for the fatal adolescence onset epilepsy Lafora disease.

Therapeutic Developments for Tics and Myoclonus.

Tics and myoclonus are phenomenologically similar given that both are jerk-like movements, but, in contrast to myoclonus, tics are often preceded by premonitory sensations and are typically associated with a variety of behavioral comorbidities, including attention deficit and obsessive-compulsive disorder. There are many other clinical features that help differentiate these two hyperkinetic disorders. Whereas behavioral and antidopaminergic therapies are most effective in the management of tics, clonazepam, other anticonvulsants, and serotonergic drugs are often used to control myoclonic movements. Botulinum toxin may also be helpful in focal tics and in segmental forms of myoclonus. DBS plays an increasingly important role in the treatment of these disorders, particularly when they are generalized and are disabling despite optimal medical therapy.

An update and review of the treatment of myoclonus.

Recent advances in medications and surgical therapy for neurological disorders may offer new therapeutic options for the treatment of myoclonus. Appropriate therapy for myoclonus depends on the etiology, and in some cases, myoclonus can improve when the provoking cause is eliminated. When the underlying cause for the movements is not immediately reversible, localization, disease pathophysiology, and etiology may each play a role in determining the most appropriate symptomatic treatment of disabling myoclonic jerks. While the use of many agents is still based on small, open-label case series and anecdotes, there is a growing body of evidence from head-to-head comparative trials in several types of myoclonus that may help guide therapy. New therapies for refractory myoclonus, including sodium oxybate and even deep brain stimulation, are also being explored with increasing enthusiasm.

"Jumping stump" phenomenon.

Myoclonic spasm of an amputated extremity can be problematic for amputees and requires recognition and understanding by surgeons encountering the phenomenon. In the present brief report, we describe the condition in a female amputee after below-the-knee amputation. Our aim is to increase awareness of this condition among foot and ankle surgeons.

N-methyl-D-aspartate receptor antibody-associated movement disorder without encephalopathy.

N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a well-recognized clinico-immunological syndrome that presents with a movement disorder, cognitive decline, psychiatric symptoms, and epileptic seizures. A pure monosymptomatic presentation is rare; however, some patients present predominantly with a movement disorder in the absence of encephalopathy. Here, we describe three paediatric patients with an NMDAR antibody-mediated movement disorder: a 5-year-old female with acute onset hemichorea, a 10-year-old female with generalized chorea, and a 12-year-old male with abdominal myoclonus. These patients did not develop the characteristic encephalopathy syndrome seen in NMDAR encephalitis, but all three had other associated subtle cognitive deficits. The patients demonstrated good responses to immunotherapy.

Medically assisted hydration for adult palliative care patients.

BACKGROUND: Many palliative care patients have reduced oral intake during their illness. The management of this can include the provision of medically assisted hydration with the aim of prolonging the life of a patient, improving their quality of life, or both. This is an updated version of the original Cochrane review published in Issue 2, 2008, and updated in February 2011. OBJECTIVES: To determine the effect of medically assisted hydration in palliative care patients on their quality and length of life. SEARCH METHODS: We identified studies by searching the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, CANCERLIT, Caresearch, Dissertation abstracts, SCIENCE CITATION INDEX and the reference lists of all eligible studies, key textbooks and previous systematic reviews. The date of the latest search conducted on CENTRAL, MEDLINE and EMBASE was March 2014. SELECTION CRITERIA: All relevant randomised controlled trials (RCTs) or prospective controlled studies of medically assisted hydration in palliative care patients. DATA COLLECTION AND ANALYSIS: We identified six relevant studies for this update. These included three RCTs (222 participants), and three prospective controlled trials (360 participants). Two review authors independently assessed the studies for quality and validity. The small number of studies and the heterogeneity of the data meant that a quantitative analysis was not possible, so we included a description of the main findings. MAIN RESULTS: One study found that sedation and myoclonus (involuntary contractions of muscles) scores were improved more in the intervention group. Another study found that dehydration was significantly higher in the non-hydration group, but that some fluid retention symptoms (pleural effusion, peripheral oedema and ascites) were significantly higher in the hydration group. The other four studies (including the three RCTs) did not show significant differences in outcomes between the two groups. The only study that had survival as an outcome found no difference in survival between the hydration and control arms. AUTHORS' CONCLUSIONS: Since the last version of this review, we found one new study. The studies published do not show a significant benefit in the use of medically assisted hydration in palliative care patients; however, there are insufficient good-quality studies to inform definitive recommendations for practice with regard to the use of medically assisted hydration in palliative care patients.

Effect of positive airway pressure treatment on excessive fragmentary myoclonus in 100 sleep-related breathing disorder patients.

STUDY OBJECTIVES: Excessive fragmentary myoclonus (EFM) is a frequent finding in patients undergoing video-polysomnography (VPSG). We aimed to evaluate the potential effect of sleep-related breathing disorder's treatment with positive airway pressure (PAP) therapy on EFM. METHODS: One hundred consecutive patients with EFM and sleep-related breathing disorder subsequently treated with PAP at the sleep lab of the Medical University of Innsbruck, Department of Neurology, Austria, were included. Each patient underwent two nights of VPSG: the first night without and the second night with PAP therapy. Fragmentary myoclonus was automatically scored with validated software, and fragmentary myoclonus index (FMI) and minutes of non-rapid eye movement (NREM) sleep with EFM (minNREM+EFM) were calculated. RESULTS: Under PAP therapy there was a significant decrease in the minNREM+EFM - 60.5 (9.5-161.8) at baseline vs. 37.5 (6.3-168.8) minutes under PAP, p = 0.025. No significant differences were observed for FMI between the two nights. Sleep variables, sleep diagnoses, comorbidities, and medication did not influence FMI or the minNREM+EFM. CONCLUSIONS: The initiation of PAP treatment led to a significant reduction of minNREM+EFM, but not of FMI. The results suggest that PAP therapy might influence the distribution of FM potentials.