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Tremor and Other Hyperkinetic Movements... 2023Peripherally-induced movement disorders (PIMD) should be considered when involuntary or abnormal movements emerge shortly after an injury to a body part. A close... (Review)
Review
BACKGROUND
Peripherally-induced movement disorders (PIMD) should be considered when involuntary or abnormal movements emerge shortly after an injury to a body part. A close topographic and temporal association between peripheral injury and onset of the movement disorders is crucial to diagnosing PIMD. PIMD is under-recognized and often misdiagnosed as functional movement disorder, although both may co-exist. Given the considerable diagnostic, therapeutic, and psychosocial-legal challenges associated with PIMD, it is crucial to update the clinical and scientific information about this important movement disorder.
METHODS
A comprehensive PubMed search through a broad range of keywords and combinations was performed in February 2023 to identify relevant articles for this narrative review.
RESULTS
The spectrum of the phenomenology of PIMD is broad and it encompasses both hyperkinetic and hypokinetic movements. Hemifacial spasm is probably the most common PIMD. Others include dystonia, tremor, parkinsonism, myoclonus, painful leg moving toe syndrome, tics, polyminimyoclonus, and amputation stump dyskinesia. We also highlight conditions such as neuropathic tremor, pseudoathetosis, and -associated myogenic tremor as examples of PIMD.
DISCUSSION
There is considerable heterogeneity among PIMD in terms of severity and nature of injury, natural course, association with pain, and response to treatment. As some patients may have co-existing functional movement disorder, neurologists should be able to differentiate the two disorders. While the exact pathophysiology remains elusive, aberrant central sensitization after peripheral stimuli and maladaptive plasticity in the sensorimotor cortex, on a background of genetic (two-hit hypothesis) or other predisposition, seem to play a role in the pathogenesis of PIMD.
Topics: Humans; Tremor; Movement Disorders; Dystonic Disorders; Tic Disorders; Dyskinesias; Myoclonus
PubMed: 37008994
DOI: 10.5334/tohm.758 -
Neurotherapeutics : the Journal of the... Oct 2020Myoclonus can cause significant disability for patients. Myoclonus has a strikingly diverse array of underlying etiologies, clinical presentations, and... (Review)
Review
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.
Topics: Anticonvulsants; Deep Brain Stimulation; Electroencephalography; Electromyography; Electrophysiological Phenomena; Humans; Myoclonus; Transcranial Magnetic Stimulation; Treatment Outcome
PubMed: 32910414
DOI: 10.1007/s13311-020-00922-6 -
Neurotherapeutics : the Journal of the... Jan 2014Myoclonus creates significant disability for patients. This symptom or sign can have many different etiologies, presentations, and pathophysiological mechanisms. A... (Review)
Review
Myoclonus creates significant disability for patients. This symptom or sign can have many different etiologies, presentations, and pathophysiological mechanisms. A thorough evaluation for the myoclonus etiology is critical for developing a treatment strategy. The best etiological classification scheme is a modified version from that proposed by Marsden et al. in 1982. Clinical neurophysiology, as assessed by electromyography and electroencephalography, can be used to classify the pathophysiology of the myoclonus using a neurophysiology classification scheme. If the etiology of the myoclonus cannot be reversed or treated, then symptomatic treatment of the myoclonus itself may be warranted. Unfortunately, there are few controlled studies for myoclonus treatments. The treatment strategy for the myoclonus is best derived from the neurophysiology classification scheme categories: 1) cortical, 2) cortical-subcortical, 3) subcortical-nonsegmental, 4) segmental, and 5) peripheral. A cortical physiology classification is most common. Levetiracetam is suggested as first-line treatment for cortical myoclonus, but valproic acid and clonazepam are commonly used. Cortical-subcortical myoclonus is the physiology demonstrated by myoclonic seizures, such as in primary epileptic myoclonus (e.g., juvenile myoclonic epilepsy). Valproic acid has demonstrated efficacy in such epileptic syndromes with other medications providing an adjunctive role. Clonazepam is used for subcortical-nonsegmental myoclonus, but other treatments, depending on the syndrome, have been used for this physiological type of myoclonus. Segmental myoclonus is difficult to treat, but clonazepam and botulinum toxin are used. Botulinum toxin is used for focal examples of peripheral myoclonus. Myoclonus treatment is commonly not effective and/or limited by side effects.
Topics: Anticonvulsants; Humans; Myoclonus
PubMed: 24037428
DOI: 10.1007/s13311-013-0216-3 -
Journal of Postgraduate Medicine 2016Asterixis is a type of negative myoclonus characterized by irregular lapses of posture of various body parts. It is an uncommon but important sign in clinical neurology.... (Review)
Review
Asterixis is a type of negative myoclonus characterized by irregular lapses of posture of various body parts. It is an uncommon but important sign in clinical neurology. Initially described as a "liver flap," its utility encompasses a galaxy of neurological and nonneurological situations. Asterixis has a rich history. Despite being described over 70 years ago, its exact pathogenesis remains unknown. Its significance as a tool for the evaluation and prognosis of encephalopathies has been suggested. This review presents its history, clinical implications and its significance.
Topics: Brain; Dyskinesias; Humans; Movement Disorders; Myoclonus
PubMed: 27089111
DOI: 10.4103/0022-3859.180572 -
Epilepsia Open Apr 2024Myoclonus 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... (Review)
Review
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.
Topics: Humans; Myoclonus; Diagnosis, Differential; Movement Disorders; Epilepsy; Epileptic Syndromes
PubMed: 38334331
DOI: 10.1002/epi4.12917 -
Journal of Veterinary Internal Medicine May 2022Myoclonus is observed in older Cavalier King Charles Spaniels (CKCS) but a full description is lacking.
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.
Topics: Animals; Dog Diseases; Dogs; Humans; Myoclonus; Retrospective Studies; Seizures
PubMed: 35319117
DOI: 10.1111/jvim.16404 -
Tremor and Other Hyperkinetic Movements... 2019Movement disorders of respiration are rare and are restricted to a phase of the respiratory cycle.
BACKGROUND
Movement disorders of respiration are rare and are restricted to a phase of the respiratory cycle.
PHENOMENOLOGY SHOWN
The intermittent inspiratory myoclonus in this patient with post-anoxic encephalopathy is likely to be of brainstem origin.
EDUCATIONAL VALUE
Rare movement disorders can be identified even in remote areas of the world where access to neurological care is limited.
Topics: Aged; Diagnosis, Differential; Fatal Outcome; Humans; Male; Myoclonus; Respiration
PubMed: 30809420
DOI: 10.7916/3qs5-cv76 -
Neurology Feb 2018To determine the contribution of electrophysiologic testing in the diagnosis and anatomical classification of myoclonus.
OBJECTIVE
To determine the contribution of electrophysiologic testing in the diagnosis and anatomical classification of myoclonus.
METHODS
Participants with a clinical diagnosis of myoclonus were prospectively recruited, each undergoing a videotaped clinical examination and battery of electrophysiologic tests. The diagnosis of myoclonus and its subtype was reviewed after 6 months in the context of the electrophysiologic findings and specialist review of the videotaped clinical examination.
RESULTS
Seventy-two patients with myoclonus were recruited. Initial clinical anatomical classification included 25 patients with cortical myoclonus, 7 with subcortical myoclonus, 2 with spinal myoclonus, and 15 with functional myoclonic jerks. In 23 cases, clinical anatomical classification was not possible because of the complexity of the movement disorder. Electrophysiologic testing was completed in 66, with agreement of myoclonus in 60 (91%) and its subtype in 28 (47%) cases. Subsequent clinical review by a movement disorder specialist agreed with the electrophysiologic findings in 52 of 60; in the remaining 8, electrophysiologic testing was inconclusive.
CONCLUSIONS
Electrophysiologic testing is an important additional tool in the diagnosis and anatomical classification of myoclonus, also aiding in decision-making regarding therapeutic management. Further development of testing criteria is necessary to optimize its use in clinical practice.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Child; Electrodiagnosis; Female; Follow-Up Studies; Humans; Male; Middle Aged; Myoclonus; Neurologic Examination; Prospective Studies; Severity of Illness Index; Video Recording; Young Adult
PubMed: 29352095
DOI: 10.1212/WNL.0000000000004996 -
Journal of Alzheimer's Disease : JAD 2017Patients with Alzheimer's disease (AD) are more prone to seizures and myoclonus, but relative risk of these symptoms among other dementia types is unknown.
BACKGROUND
Patients with Alzheimer's disease (AD) are more prone to seizures and myoclonus, but relative risk of these symptoms among other dementia types is unknown.
OBJECTIVE
To determine incidence of seizures and myoclonus in the three most common neurodegenerative dementias: AD, dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD).
METHODS
Our institution's medical records were reviewed for new-onset unprovoked seizures and myoclonus in patients meeting criteria for AD (n = 1,320), DLB (n = 178), and FTD (n = 348). Cumulative probabilities of developing seizures and myoclonus were compared between diagnostic groups, whereas age-stratified incidence rates were determined relative to control populations.
RESULTS
The cumulative probability of developing seizures after disease onset was 11.5% overall, highest in AD (13.4%) and DLB (14.7%) and lowest in FTD (3.0%). The cumulative probability of developing myoclonus was 42.1% overall, highest in DLB (58.1%). The seizure incidence rates, relative to control populations, were nearly 10-fold in AD and DLB, and 6-fold in FTD. Relative seizure rates increased with earlier age-at-onset in AD (age <50, 127-fold; 50-69, 21-fold; 70+, 2-fold) and FTD (age <50, 53-fold; 50-69, 9-fold), and relative myoclonus rates increased with earlier age-at-onset in all groups. Seizures began an average of 3.9 years after the onset of cognitive or motor decline, and myoclonus began 5.4 years after onset.
CONCLUSIONS
Seizures and myoclonus occur with greater incidence in patients with AD, DLB, and FTD than in the general population, but rates vary with diagnosis, suggesting varied pathomechanisms of network hyperexcitability. Patients often experience these symptoms early in disease, suggesting hyperexcitability could be an important target for interventions.
Topics: Age Distribution; Aged; Alzheimer Disease; Female; Frontotemporal Dementia; Humans; Incidence; Lewy Body Disease; Male; Middle Aged; Myoclonus; Psychiatric Status Rating Scales; Retrospective Studies; Seizures; Severity of Illness Index
PubMed: 28826176
DOI: 10.3233/JAD-170031 -
Journal of Veterinary Internal Medicine Jul 2017Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one... (Review)
Review
Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one hand, a classification system is required that is clinically useful to aid in guiding diagnosis and treatment. On the other hand, there is need for a system that organizes current knowledge regarding biological mechanisms to guide scientific research. These 2 needs are distinct, making it challenging to develop a robust classification system suitable for all purposes. We attempt to classify myoclonus as "epileptic" and "nonepileptic" based on its association with epileptic seizures. Myotonia in people may be divided into 2 clinically and molecularly defined forms: (1) nondystrophic myotonias and (2) myotonic dystrophies. The former are a group of skeletal muscle channelopathies characterized by delayed skeletal muscle relaxation. Many distinct clinical phenotypes are recognized in people, the majority relating to mutations in skeletal muscle voltage-gated chloride (CLCN1) and sodium channel (SCN4A) genes. In dogs, myotonia is associated with mutations in CLCN1. The myotonic dystrophies are considered a multisystem clinical syndrome in people encompassing 2 clinically and molecularly defined forms designated myotonic dystrophy types 1 and 2. No mutation has been linked to veterinary muscular dystrophies. We detail veterinary examples of myotonia and attempt classification according to guidelines used in humans. This more precise categorization of myoclonus and myotonia aims to promote the search for molecular markers contributing to the phenotypic spectrum of disease. Our work aimed to assist recognition for these 2 enigmatic conditions.
Topics: Animals; Dog Diseases; Dogs; Dyskinesias; Myoclonus; Myotonia
PubMed: 28557061
DOI: 10.1111/jvim.14771