Myoclonus

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.

Bedside clinical assessment of patients with common upper limb tremor and algorithmic approach

The diagnostic approach for patients with tremor is challenging due to the complex and overlapping phenotypes among tremor syndromes. The first step in the evaluation of tremor is to identify the tremulous movement and exclude the tremor mimics. The second step is to classify the tremor syndrome based on the characteristics of tremor from historical clues and focused examination (Axis 1). Comprehensive tremor examinations involve the assessment of tremor in different conditions (rest, action or mixed, position or task-specific), distribution of tremor (upper limb, lower limb, head, jaw), positive signs for functional tremor (FT) if suspected (distractibility, entrainment, co-contraction), and associated neurological signs including parkinsonism, dystonic posture, cerebellar/brainstem signs, neuropathy, and cognitive impairment. A pivotal feature in this step is to determine any distinct feature of a specific isolated or combined tremor syndrome. In this review, we propose an algorithm to assess upper limb tremors. Ancillary testing should be performed if clinical evaluation is unclear. The choice of investigation depends on the types of tremors considered to narrow down the spectrum of etiology (Axis 2). Laboratory blood tests are considered for acute onset and acute worsening of tremors, while structural neuroimaging is indicated in unilateral tremors with acute onset, nonclassical presentations, and a combination of neurological symptoms. Neurophysiological study is an important tool that aids in distinguishing between tremor and myoclonus, etiology of tremor and document specific signs of FT. Treatment is mainly symptomatic based depending on the etiology of the tremor and the patient's disabilities.

Myoclonus in older Cavalier King Charles Spaniels

Background

Myoclonus is observed in older Cavalier King Charles Spaniels (CKCS) but a full description is lacking.

Objectives

The presence, age of onset, characteristics and treatment of myoclonic episodes were retrospectively evaluated in a cohort of CKCS which presented to 1 board‐certified neurologist. Clinical data, imaging studies, presence of seizures and their management, as well as other comorbidities were noted.

Animals

Thirty‐nine CKCS that were presented to 2 institutions between 2001 and 2018 with signs consistent with myoclonus. Clinical examination, blood sampling, advanced diagnostic imaging, cerebrospinal fluid analysis, and record keeping of other comorbidities was performed.

Methods

This is a retrospective case series, describing the presence of myoclonus in CKCS.

Results

Clinical signs reported were spontaneous in onset, lasted a few seconds and consisted of rapid blinking with head nodding and variable extension down the thoracic limbs. Myoclonus occasionally led to stumbling of the thoracic limbs or collapse. Mean age of onset was 8.38 years (SD ±1.96). Thirteen of 39 dogs with myoclonus had paroxysmal events, such as generalized seizures (9/13).

Conclusions and Clinical Importance

Myoclonus occurs in middle‐aged to older CKCS and seems to be another epiphenomena of this breed. A link to epilepsy might be present.

Assessment and Treatment of Myoclonus: A Review

Myoclonus is defined as sudden, brief, shock-like contractions of muscles, and it can be a challenging diagnosis for the clinician to face. The number of aetiologies can make it difficult to determine the appropriate diagnostic workup for each individual patient without ordering a broad array of diagnostic studies from the start. As with other neurological conditions, a comprehensive history and physical examination are paramount in generating and ordering the initial differential diagnosis. Neurophysiological classification of myoclonus, using both electroencephalogram and electromyography, can be very helpful in elucidating the underlying aetiology. Treatment of myoclonus is often symptomatic, unless a clear treatable underlying cause can be found. This article aims to help providers navigate the assessment and treatment of myoclonus, focusing on neurophysiological classification as a guide. By the end of this article, providers should have a good understanding of how to approach the workup and treatment of myoclonus of various aetiologies.

Tramadol Induced Jerks

Myoclonus is a sudden, involuntary jerking of a muscle or a group of muscles. Myoclonus may present in form of a pattern or, sporadically and infrequently. It is usually associated with neurological disorders such as epilepsy, multiple sclerosis or infections, and tumors of the central nervous system. Myoclonus is not commonly known to be caused by tramadol. We present a case of a 59-year-old male who developed myoclonus in the muscles of his trunk, 10 days after initiating tramadol for chronic pain. The myoclonus disappeared after withholding the medication. The purpose of this case report is to make clinicians aware of a rare reversible side effect from the use of tramadol.

Myoclonus- A Review

Myoclonus is a hyperkinetic movement disorder characterized by a sudden, brief, involuntary jerk. Positive myoclonus is caused by abrupt muscle contractions, while negative myoclonus by sudden cessation of ongoing muscular contractions. Myoclonus can be classified in various ways according to body distribution, relation to activity, neurophysiology, and etiology. The neurophysiological classification of myoclonus by means of electrophysiological tests is helpful in guiding the best therapeutic strategy. Given the diverse etiologies of myoclonus, a thorough history and detailed physical examination are key to the evaluation of myoclonus. These along with basic laboratory testing and neurophysiological studies help in narrowing down the clinical possibilities. Though symptomatic treatment is required in the majority of cases, treatment of the underlying etiology should be the primary aim whenever possible. Symptomatic treatment is often not satisfactory, and a combination of different drugs is often required to control the myoclonus. This review addresses the etiology, classification, clinical approach, and management of myoclonus.

Negative Myoclonus Secondary to Thalamic Infarction: Case Report

Background

Movement disorders are an infrequent presentation to stroke, and in this context, negative myoclonus is not among the most common movement disorders, hence we present a case of negative myoclonus secondary to thalamic stroke.

Case

A 75 year old male presented with left central facial palsy and negative myoclonus on his left upper limb. He was submitted to a diagnostic workup, with evidence of a right thalamic stroke. He was started on Phenobarbital 50 mg and the movement disorder resolved.

Conclusion

Given the relevance of cerebrovascular disease as a cause of morbidity and mortality, it is important to the clinician to be aware of the less typical presentations such as the observed in our case, in order to provide adequate care to the patient.

Jerks of the latissimus dorsi muscle and intercostal neuralgia after posterolateral thoracotomy

Introduction

Post-thoracotomy pain syndrome (PTPS) is a common complication related to intercostal nerve injury. During this type of surgery, although less frequently, thoracodorsal and long thoracic nerves can also be injured, and jerks of peripheral origins may appear. We report a case with intercostal neuralgia and latissimus dorsi muscle jerks after posterolateral thoracotomy.

Case report

A 55-year-old woman with Ehlers-Danlos Syndrome presented with a typical picture of PTPS along the right T5 dermatome following posterolateral thoracotomy at the level of the fifth intercostal space. Approximately six months after the surgery she developed frequent jerk-like involuntary movements of the right latissimus dorsi muscle. Neuropathic pain along the T5 dermatome was partially relieved with thoracic epidural block. No special attention was paid to the jerks until three years later. A neurophysiological study demonstrated a peripheral origin of these movements and the patient was then treated with periodic injections of botulinum toxin. In response, involuntary movements of the latissimus dorsi muscle disappeared.

Significance

To our knowledge, this is the first case with PTPS and post-thoracotomy latissimus dorsi muscle jerks in a patient with Ehlers-Danlos Syndrome. A correct diagnosis together with identification of iatrogenic neuropathic disorders allow the delivery of targeted treatments. In such cases clinical neurophysiology helps to determine a correct diagnosis.

Opsoclonus-myoclonus syndrome, a post-infectious neurologic complication of COVID-19: case series and review of literature

Opsoclonus-myoclonus-ataxia syndrome is a heterogeneous constellation of symptoms ranging from full combination of these three neurological findings to varying degrees of isolated individual sign. Since the emergence of coronavirus disease 2019 (COVID-19), neurological symptoms, syndromes, and complications associated with this multi-organ viral infection have been reported and the various aspects of neurological involvement are increasingly uncovered. As a neuro-inflammatory disorder, one would expect to observe opsoclonus-myoclonus syndrome after a prevalent viral infection in a pandemic scale, as it has been the case for many other neuro-inflammatory syndromes. We report seven cases of opsoclonus-myoclonus syndrome presumably parainfectious in nature and discuss their phenomenology, their possible pathophysiological relationship to COVID-19, and diagnostic and treatment strategy in each case. Finally, we review the relevant data in the literature regarding the opsoclonus-myoclonus syndrome and possible similar cases associated with COVID-19 and its diagnostic importance for clinicians in various fields of medicine encountering COVID-19 patients and its complications.

Video electroencephalogram combined with electromyography in the diagnosis of hyperkinetic movement disorders with an unknown cause

OBJECTIVES

Diagnosis of hyperkinetic movement disorders with an unknown cause is usually challenging. The objective of this study is to learn about video electroencephalogram (VEEG) combined with electromyography (EMG) in the diagnosis of hyperkinetic movement disorders with an unknown cause.

METHODS

We performed an observational cohort study by recruiting consecutive patients with hyperkinetic movements as the main manifestation with an unknown cause for VEEG combined with EMG evaluations.

RESULTS

A total of 77 consecutive patients were enrolled for VEEG-EMG examination. Among them, 57 patients changed their diagnosis after VEEG-EMG assessment, with a mean final diagnosis age of 35.4 ± 20.3 years (range, 4-74 years). The mean duration between initial and final diagnosis was 54.8 ± 71.3 months (range 0.5-300 months). The most common misdiagnosed hyperkinetic movement disorders were myoclonus (40.4%), followed by tremors (24.6%), dystonia (15.8%), psychogenic movement disorders (10.5%), and periodic leg movement syndrome (PLMS) (7.0%). Outcomes of therapy were significantly improved after VEEG-EMG examination (p = 0.000).

CONCLUSIONS

Simultaneous VEEG and EMG are important in the diagnosis of hyperkinetic movement disorders with an unknown cause.