Myoclonus: Differential diagnosis and current management.

Myoclonus classically presents as a brief (10-50 ms duration), non-rhythmic jerk movement. The etiology could vary considerably ranging from self-limited to chronic or even progressive disorders, the latter falling into encephalopathic pictures that need a prompt diagnosis. Beyond the etiological classification, others evaluate myoclonus' body distribution (i.e., clinical classification) or the location of the generator (i.e., neurophysiological classification); particularly, knowing the anatomical source of myoclonus gives inputs on the observable clinical patterns, such as EMG bursts duration or EEG correlate, and guides the therapeutic choices. Among all the chronic disorders, myoclonus often presents itself as a manifestation of epilepsy. In this context, myoclonus has many facets. Myoclonus occurs as one, or the only, seizure manifestation while it can also present as a peculiar type of movement disorder; moreover, its electroclinical features within specific genetically determined epileptic syndromes have seldom been investigated. In this review, following a meeting of recognized experts, we provide an up-to-date overview of the neurophysiology and nosology surrounding myoclonus. Through the dedicated exploration of epileptic syndromes, coupled with pragmatic guidance, we aim to furnish clinicians and researchers alike with practical advice for heightened diagnostic management and refined treatment strategies. PLAIN LANGUAGE SUMMARY: In this work, we described myoclonus, a movement characterized by brief, shock-like jerks. Myoclonus could be present in different diseases and its correct diagnosis helps treatment.

Deep Brain Stimulation for an Unusual Presentation of Myoclonus Dystonia Associated with Russell-Silver Syndrome.

Background: Myoclonus dystonia syndrome typically results from autosomal dominant mutations in the epsilon-sarcoglycan gene (SGCE) via the paternally expressed allele on chromosome 7q21. There is evidence that deep brain stimulation (DBS) is beneficial for this genotype, however, there are few prior case reports on DBS for myoclonus dystonia syndrome secondary to other confirmed genetic etiologies. Case Report: A 20-year-old female with concomitant Russell-Silver syndrome and myoclonus dystonia syndrome secondary to maternal uniparental disomy of chromosome 7 (mUPD7) presented for medically refractory symptoms. She underwent DBS surgery targeting the bilateral globus pallidus interna with positive effects that persisted 16 months post-procedure. Discussion: We present a patient with the mUPD7 genotype for myoclonus dystonia syndrome who exhibited a similar, if not superior, response to DBS when compared to patients with other genotypes. Highlights: This report outlines the first described case of successful deep brain stimulation treatment for a rare genetic variant of myoclonus dystonia syndrome caused by uniparental disomy at chromosome 7. These findings may expand treatment options for patients with similar conditions.

[Treatment Methods for Dystonia, Myoclonus, and Chorea].

Abnormal involuntary movement (AIM) are usually classified into hypokinesia and hyperkinesia group. Hyperkinesia-AIM includes myoclonus, chorea, ballism, dystonia, athetosis, and more. Of these, dystonia, myoclonus, and chorea are frequent movement disorders. From a neurophysiological point of view, the mechanism of motor control by the basal ganglia is thought to consist of three pathways: hyperdirect, direct, and indirect. Hyperkinetic-AIMs are likely caused by the dysfunction of any of these three pathways, leading to malfunction in either presurround inhibition, initiation of motor performance, or postsurround inhibition. These dysfunctions are assumed to stem from regions, such as the cerebral cortex, white matter, basal ganglia, brainstem, and cerebellum. Drug therapies that consider the pathogenesis mechanism are desirable. Here, we presented an overview of treatment methods for hyperkinetic-AIMs.

Myoclonus in comatose patients with electrographic status epilepticus after cardiac arrest: Corresponding EEG patterns, effects of treatment and outcomes.

OBJECTIVE: To clarify the significance of any form of myoclonus in comatose patients after cardiac arrest with rhythmic and periodic EEG patterns (RPPs) by analyzing associations between myoclonus and EEG pattern, response to anti-seizure medication and neurological outcome. DESIGN: Post hoc analysis of the prospective randomized Treatment of ELectroencephalographic STatus Epilepticus After Cardiopulmonary Resuscitation (TELSTAR) trial. SETTING: Eleven ICUs in the Netherlands and Belgium. PATIENTS: One hundred and fifty-seven adult comatose post-cardiac arrest patients with RPPs on continuous EEG monitoring. INTERVENTIONS: Anti-seizure medication vs no anti-seizure medication in addition to standard care. MEASUREMENTS AND MAIN RESULTS: Of 157 patients, 98 (63%) had myoclonus at inclusion. Myoclonus was not associated with one specific RPP type. However, myoclonus was associated with a smaller probability of a continuous EEG background pattern (48% in patients with vs 75% without myoclonus, odds ratio (OR) 0.31; 95% confidence interval (CI) 0.16-0.64) and earlier onset of RPPs (24% vs 9% within 24 hours after cardiac arrest, OR 3.86;95% CI 1.64-9.11). Myoclonus was associated with poor outcome at three months, but not invariably so (poor neurological outcome in 96% vs 82%, p = 0.004). Anti-seizure medication did not improve outcome, regardless of myoclonus presence (6% good outcome in the intervention group vs 2% in the control group, OR 0.33; 95% CI 0.03-3.32). CONCLUSIONS: Myoclonus in comatose patients after cardiac arrest with RPPs is associated with poor outcome and discontinuous or suppressed EEG. However, presence of myoclonus does not interact with the effects of anti-seizure medication and cannot predict a poor outcome without false positives.

[Diagnosis and treatment strategies of 56 cases of middle ear myoclonus].

Objective: To analyze the clinical characteristics and treatment of middle ear myoclonus. Methods: Fifty-six cases of middle ear myoclonus were enrolled in Shandong Provincial ENT Hospital, Shandong University from September 2019 to August 2021, including 23 males and 33 females. The age ranged from 6 to 75 years, with a median age of 35 years; Forty-seven cases were unilateral tinnitus, nine cases were bilateral tinnitus. The time of tinnitus ranged from 20 days to 8 years. The voice characteristics, inducing factors, nature (frequency) of tinnitus, tympanic membrane conditions during tinnitus, audiological related tests, including long-term acoustic tympanogram, stapedius acoustic reflex, pure tone auditory threshold, short increment sensitivity test, alternate binaural loudness balance test, loudness discomfort threshold, vestibular function examination, facial electromyography, and imaging examination were recorded. Oral carbamazepine and/or surgical treatment were used. The patients were followed up for 6-24 months and the tinnitus changes were observed. Results: Tinnitus was diverse, including stepping on snow liking sound, rhythmic drumming, white noise, and so on. The inducing factors included external sound, body position change, touching the skin around the face and ears, speaking, chewing and blinking, etc. Forty-four cases were induced by single factor and 9 cases were induced by two or more factors. There was no definite inducing factor in 1 case. One patient had tinnitus with epilepsy. One case of traumatic facial paralysis after facial nerve decompression could induce tinnitus on the affected side when the auricle moved. Tympanic membrane flutter with the same frequency as tinnitus was found in 12 cases by otoscopy, and the waveform with the same frequency as tinnitus was found by long-term tympanogram examination. There were 7 patients with no tympanic membrane activity by otoscopy, the 7 cases also with the same frequency of tinnitus by long-term tympanogram examination, but the change rate of the waveform was faster than that of the patients with tympanic membrane flutter. All patients with tinnitus had no change in hearing. One case of tinnitus complicated with epilepsy (a 6-year-old child) was treated with antiepileptic drug (topiramate) and tinnitus subsided. One case suffered from tinnitus after facial nerve decompression for traumatic facial paralysis was not given special treatment. Fifty-four cases were treated with oral drug (carbamazepine), of which 10 cases were completely controlled and 23 cases were relieved; 21 cases were invalid. Among the 21 patients with no effect of carbamazepine treatment, 8 patients were treated by surgery, 7 patients had no tinnitus after surgery, 1 patient received three times of operation, and the third operation was followed up for 6 months, no tinnitus occurred again. The other 13 cases refused the surgical treatment due to personal reasons. Conclusions: Middle ear myoclonus tinnitus and the inducing factors manifestate diversity. Oral carbamazepine and other sedative drugs are effective for some patients, and surgical treatment is feasible for those who are ineffective for medication.

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.

Case report - Asterixis Post High Frequency Focused-Ultrasound Thalamotomy.

Background: High frequency focused ultrasound is used for treatment of essential tremor. Side effects associated with the procedure may resolve over time. We report a case of negative myoclonus, which has not been reported with this procedure. Case report: A 73-year-old left-handed man underwent focused ultrasound thalamotomy for treatment of essential tremor. Immediately post procedure he was noted to have negative myoclonus in the treated limb. This side effect resolved over the course of 6 months. Discussion: Although asterixis has been associated with thalamic infarcts in the past, this has not yet been reported in the literature with MRgFUS procedure and is a novel observation. Occupational and physical therapy may be considered to address this side effect. It is important to counsel patients about the rare occurrence of this complication of therapy but also its potential for complete resolution over time.

Neuropsychiatric syndrome with myoclonus after SARS-CoV-2 infection in a paediatric patient.

We report the case of a 12-years-old patient who subacutely developed a positive and negative myoclonus of limbs and face, drowsiness and memory deficits after getting infected by SARS-CoV-2. On admission, nasopharyngeal swab for SARS-CoV-2, brain and spinal MRI with and without contrast, EEG, chest X-ray and abdominal ultrasound were negative. CSF physical-chemical examination, culture, PCR testing for SARS-CoV-2 and other pathogens, and oligoclonal IgG bands were negative as well. A full panel blood test, including clotting, autoimmunity and paraneoplastic blood studies, did not show any alteration. The neuropsychological examination showed an impairment in memory, visual-motor coordination, inductive reasoning skills, attention, and concentration. The patient was first treated with clonazepam and then with intravenous methylprednisolone for five days, with poor response. For this reason, he then received a cycle of IVIG, thus reaching a gradual and complete recovery. To date, this is the first case of a COVID-19 associated myoclonus affecting a paediatric patient.

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.

Mioclonía palatina esencial. Reporte de un caso pediátrico / Essential palatal myoclonus. A pediatric case report

La mioclonía palatina esencial es una entidad otoneurológi-ca rara. Se caracteriza por movimientos involuntarios de los músculos del paladar blando que causan un tinnitus objetivo.La mioclonía del paladar se clasifica en dos tipos: secundaria y primaria (mioclonía palatina esencial); esta última es más frecuente en pediatría. La tomografía computada y la reso-nancia magnética de cerebro normal orientan al diagnóstico. La mioclonía palatina esencial, generalmente, se resuelve en forma espontánea.Se presenta a una paciente de 8 años de edad con un "clic" rápido en forma rítmica en su boca que cedía en forma espontánea

Essential palatal myoclonus is a rare neurological disorder characterized by involuntary movements of the soft palate musculature causing objective-clicking tinnitus. The palatal myoclonus is classified in two forms, secondary and essential palatal myoclonus. Primary (essential) palatal myoclonus is the most common type in childhood. Normal computed tomography and magnetic resonance guide the diagnosis. Spontaneous resolution usually occurs in the essential type of palatal myoclonus.In this report, we present an 8-year-old child making rhythmic, rapid clicking noises from her throat with spontaneous resolution.

Unexpected sequelae of the COVID-19 pandemic: A strange case of myoclonus in the Tasmanian winter.

Peritoneal dialysis treatment generates significant amounts of waste for disposal from patients' homes. In Australia, in the days after the onset of the COVID-19 pandemic, waste collection from homes was temporarily stopped. Our patient tried to dispose of his waste by burning the used bags and tubing, using paint thinner as an accelerant. We present a case report of the unusual neurological complication he developed.

Treatment of Post-Hypoxic Myoclonus using Pallidal Deep Brain Stimulation Placed Using Interventional MRI Methods.

Background: Post-hypoxic myoclonus (PHM) is characterized by generalized myoclonus after hypoxic brain injury. Myoclonus is often functionally impairing and refractory to medical therapies. Deep brain stimulation (DBS) has been used to treat myoclonus-dystonia, but few cases of PHM have been described. Case report: A 33-year-old woman developed severe, refractory generalized myoclonus after cardiopulmonary arrest from drowning. We performed MRI-guided asleep bilateral pallidal DBS placement, resulting in improvement in action myoclonus at one year. Discussion: Our case contributes to growing evidence for DBS for PHM. Interventional MRI guided DBS technique can be used for safe and accurate lead placement. Highlights: We report a case of a patient who developed post-hypoxic myoclonus after cardiopulmonary arrest from drowning, who later underwent deep brain stimulation to treat refractory myoclonus. This is the first case to describe asleep, interventional MRI-guided technique for implanting DBS leads in post-hypoxic myoclonus.

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.

Physiology-Based Treatment of Myoclonus.

Myoclonus can cause significant disability for patients. Myoclonus has a strikingly diverse array of underlying etiologies, clinical presentations, and pathophysiological mechanisms. Treatment of myoclonus is vital to improving the quality of life of patients with these disorders. The optimal treatment strategy for myoclonus is best determined based upon careful evaluation and consideration of the underlying etiology and neurophysiological classification. Electrophysiological testing including EEG (electroencephalogram) and EMG (electromyogram) data is helpful in determining the neurophysiological classification of myoclonus. The neurophysiological subtypes of myoclonus include cortical, cortical-subcortical, subcortical-nonsegmental, segmental, and peripheral. Levetiracetam, valproic acid, and clonazepam are often used to treat cortical myoclonus. In cortical-subcortical myoclonus, treatment of myoclonic seizures is prioritized, valproic acid being the mainstay of therapy. Subcortical-nonsegmental myoclonus may be treated with clonazepam, though numerous agents have been used depending on the etiology. Segmental and peripheral myoclonus are often resistant to treatment, but anticonvulsants and botulinum toxin injections may be of utility depending upon the case. Pharmacological treatments are often hampered by scarce evidence-based knowledge, adverse effects, and variable efficacy of medications.

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.