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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 re...
Context in source publication
Context 1
... we will focus on the symptomatic treatment of myoclonus. Table 1 Potentially reversible causes of myoclonus and suggested diagnostic evaluation Potentially reversible etiology Clinical signs or symptoms Evaluation a Metabolic Hyperthyroidism Grave's ophthalmopathy, weight loss, palpitations TSH, fT4, fT3, anti-thyroperoxidase Ab, anti-thyroglobulin Ab Hepatic failure Jaundice, ascites, edema, encephalopathy, seizures 1. AST/ALT, bilirubin, protein, GGT 2. HAV, HBV, HCV, acetaminophen, alpha-1 antitrypsin, ammonia Hyponatremia Encephalopathy, skin hyperpigmentation (Addison's), fatigue Chemistry panel, ACTH challenge Renal failure/dialysis syndrome Edema, blood pressure fluctuations, seizures, headache, negative myoclonus Table 2. Using the anatomic localization and neu- rophysiologic classification as a general outline for a treatment algorithm ( Fig. 1), we have incorporated clinical findings such as triggers and underlying etiology to further tailor therapeutic recommendations. ...
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Recent advances...
Citations
... The results are summarized (Table 1). The localization of the extrusion was as follows: C2-C3 (n = 10), C3-C4 (5), and C4-C5 (5). The degree of spinal cord compression was calculated between 12% and 49%. ...
... In human medicine, the term myoclonus encompasses a large spectrum of signs, arising both from central and peripheral nervous systems. 1,4,5 In veterinary medicine, myoclonus is usually described as a sudden, brief, shock-like involuntary movement or a sequence of repeated, often arrhythmic jerks due to sudden involuntary contraction or relaxation of 1 or more muscles. This is usually associated with movement of a body part. ...
... The first one is peripheral myoclonus, which presents as focal jerks affecting muscles in the distribution of a peripheral nerve root or nerve at the level of the nerve root involved. 5 The second type of myoclonus is spinal segmental myoclonus (SSM), which usually relates to spinal cord pathology (due to spinal cord injury, herpes myelitis, or demyelinating disease in human beings). It usually consists of rhythmic movements in the area innervated by the affected spinal segment. ...
OBJECTIVE
To describe and classify cervical muscle jerks associated with cervical pain or myelopathy and evaluate their clinical and diagnostic relevance.
ANIMALS
20 dogs with a history of unilateral or bilateral cervical jerks associated with cervical pain or myelopathy.
PROCEDURES
A retrospective study. Detailed history, complete clinical and neurological examinations, CT studies, and outcome were available for each dog. All dogs received a treatment adapted to each diagnosis. The presence or absence of jerks was evaluated at short- and long-term recheck examinations. An immediate postoperative CT scan was obtained for all cases that were treated surgically.
RESULTS
20 dogs were selected for the study, 13 of which were French Bulldogs. Jerks all presented as focal repetitive rhythmic contractions on the lateral aspect of the neck (on one or both sides). All dogs had a diagnosis of cervical intervertebral disk extrusion (IVDE), half of them at the C2-C3 level. No dogs presented with extrusion caudal to the C4-C5 intervertebral disk space. The prevalence of myoclonia among all dogs diagnosed with IVDE was 3.77% (20/530) in our hospital.
CLINICAL RELEVANCE
Cervical jerk associated with cervical pain or myelopathy may represent myoclonus and was exclusively secondary to cranial cervical IVDE in this study. Full recovery was observed following medical or surgical treatment of IVDE. The exact origin and classification of this involuntary movement has yet to be established.
... The idea of a subcortical site of origin of the myoclonus had already been proposed in other progressive myoclonic epilepsies (Cantello et al., 1997) but to date not in sialidosis. This is important not only to have a better understanding of the physiopathology of the disease but also thinking about therapeutic approaches as there is medication, such as clonazepam, known to be more effective for the treatment of subcortical myoclonus than other antimyoclonic medication (Mills and Mari, 2015). ...
Objective
Sialidosis is an inborn error of metabolism. There is evidence that the myoclonic movements observed in this disorder have a cortical origin, but this mechanism does not fully explain the bilaterally synchronous myoclonus activity frequently observed in many patients. We present evidence of a subcortical basis for synchronous myoclonic phenomena.
Methods
Electromyographic investigations were undertaken in two molecularly and biochemically confirmed patients with sialidosis type-1.
Results
The EMG recordings showed clear episodes of bilaterally synchronous myoclonic activity in contralateral homologous muscles. We also observed a high muscular-muscular coherence with near-zero time-lag between these muscles.
Conclusion
The absence of coherence phase lag between the right-and-left homologous muscles during synchronous events indicates that a unilateral cortical source cannot fully explain the myoclonic activity. There must exist a subcortical mechanism for bilateral synchronization accounting for this phenomenon.
Significance
Understanding this mechanism may illuminate cortical-subcortical relationships in myoclonus.
... antigravity (isometric) muscle activity and tone resulting in postural instability or falling. [1][2][3][4][5][6] Myoclonus can be a consequence of many diseases and categorization is based on clinical presentation, physiology, and etiology. In humans, clinical presentation distinguishes physiological, essential, epileptic, and symptomatic myoclonus. ...
... In humans, clinical presentation distinguishes physiological, essential, epileptic, and symptomatic myoclonus. [2][3][4]6,7 Physiological myoclonus is a common phenomenon, for example hypnic jerks (muscle twitch as falling asleep) or hiccups (a myoclonus of the diaphragm). [1][2][3][4][5][6]8 Essential myoclonus can be hereditary or sporadic. ...
... [2][3][4]6,7 Physiological myoclonus is a common phenomenon, for example hypnic jerks (muscle twitch as falling asleep) or hiccups (a myoclonus of the diaphragm). [1][2][3][4][5][6]8 Essential myoclonus can be hereditary or sporadic. ...
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.
... The degree to which myoclonus improves with treatment depends on the underlying etiology. Certain types of myoclonus may be secondary to potentially treatable etiologies as an inflammatory disorder or a metabolic disturbance [11]. ...
Background
Electrophysiological techniques have been used for discriminating myoclonus from other hyperkinetic movement disorders and for classifying the myoclonus subtype. This study was carried out on patients with different subtypes of myoclonus to determine the electrophysiological characteristics and the anatomical classification of myoclonus of different etiologies. This study included 20 patients with different subtypes of myoclonus compared with 30 control participants. Electrophysiological study was carried out for all patients by somatosensory evoked potential (SSEP) and electroencephalography (EEG) while the control group underwent SSEP. SSEP was evaluated in patients and control groups by stimulation of right and left median nerves.
Results
This study included 50 cases with myoclonus of different causes with mean age of 39.3 ± 15.7 and consisted of 23 males and 27 females. Twenty-nine (58%) of the patients were epileptics, while 21 (42%) were non-epileptics. Cases were classified anatomically into ten cases with cortical myoclonus (20%), 12 cases with subcortical myoclonus (24%), and 28 cases with cortical–subcortical myoclonus (56%). There was a significant difference regarding the presence of EEG findings in epileptic myoclonic and non-epileptic myoclonic groups ( P = 0.005). Also, there were significant differences regarding P24 amplitude, N33 amplitude, P24–N33 peak-to-peak complex amplitude regarding all types of myoclonus. Primary myoclonic epilepsy (PME) demonstrated significant giant response, juvenile myoclonic epilepsy (JME) demonstrated no enhancement compared to controls, while secondary myoclonus demonstrated lower giant response compared to PME.
Conclusion
Somatosensory evoked potential and electroencephalography are important for the diagnosis and anatomical sub-classification of myoclonus and so may help in decision-making regarding to the subsequent management.
... Myoclonus is a movement disorder characterized by brief, sudden, involuntary muscle jerks. It arises from all levels of the nervous system, including the cortical and subcortical areas, brainstem, spinal cord, and peripheral areas, and causes muscle contractions (positive myoclonus) or brief inhibition during sustained posture (negative myoclonus) [355]. Tics and myoclonus may be visibly indistinguishable, but some clinical features are useful to distinguish them. ...
Tics are characterized by sudden, rapid, recurrent, nonrhythmic movement or vocalization, and are the most common movement disorders in children. Their onset is usually in childhood and tics often will diminish within one year. However, some of the tics can persist and cause various problems such as social embarrassment, physical discomfort, or emotional impairments, which could interfere with daily activities and school performance. Furthermore, tic disorders are frequently associated with comorbid neuropsychiatric symptoms, which can become more problematic than tic symptoms. Unfortunately, misunderstanding and misconceptions of tic disorders still exist among the general population. Understanding tic disorders and their comorbidities is important to deliver appropriate care to patients with tics. Several studies have been conducted to elucidate the clinical course, epidemiology, and pathophysiology of tics, but they are still not well understood. This article aims to provide an overview about tics and tic disorders, and recent findings on tic disorders including history, definition, diagnosis, epidemiology, etiology, diagnostic approach, comorbidities, treatment and management, and differential diagnosis.
... [14] The best strategy for symptomatic treatment is to define the physiological classification of myoclonus with the help of neurophysiological test/s because different drugs act in different physiological types of myoclonus. [67] Moreover, a drug useful in one physiological type may not work in another type of myoclonus or may even worsen it. All drugs should be started at a low dose followed by gradual increment considering the potential side effects (e.g., sedation, worsening of cognition, ataxia). ...
... Medications such as phenytoin, carbamazepine, oxcarbazepine, lamotrigine, gabapentin, pregabalin, and vigabatrin aggravate the cortical myoclonus and are usually avoided. [67] Gait disturbances secondary to negative myoclonus and asterixis are usually difficult to treat and are most resistant to treatment. ...
... Standard antiepileptic drugs used in cortical myoclonus are not helpful in most types of subcortical-nonsegmental myoclonus. [67] Clonazepam is the first choice in most subtypes such as brainstem reflex myoclonus, hyperekplexia, myoclonus-dystonia, and propriospinal myoclonus. Apart from GABAergic mechanisms, serotonergic and cholinergic mechanisms also play a role in the pathogenesis of brainstem reflex myoclonus. ...
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.
... 127 Oral medications commonly used to treat myoclonus include clonazepam, levetiracetam, zonisamide, valproic acid, and topiramate. 128 ...
Movement disorders presenting in childhood include tics, dystonia, chorea, tremor, stereotypy, myoclonus, and parkinsonism, each of which can be part of various clinical syndromes with distinct etiologies. Some of these conditions are benign and require only reassurance; others are bothersome and require treatment, or may be clues that herald underlying pathology. Answers lie in the inherent characteristics of the movements themselves, together with the clinical context provided in the history obtained by the examiner. The aim of this review is to present an overview of the categories of involuntary movements, along with examples of common acquired and genetic causes, and an approach to history-taking, examination, and treatment.
... Hyperthyroidism commonly results in tremor and should always be considered in patients with new-onset symptoms. Abdominal and orthostatic tremor has also been reported in thyrotoxicosis [107,108]. Treatment of thyroid dysfunction greatly improves the tremor [109]. When symptomatic treatment is required, propranolol is beneficial. ...
Purpose of review
To summarize the state of the art of therapeutic approaches for movement disorders occurring in the context of systemic disorders. These secondary movement disorders, e.g., parkinsonism, tremor, chorea, dystonia, ballism, ataxia, and dyskinesia, among others, can be transitory manifestations of systemic diseases or part of syndromes that combine systemic and neurological symptoms (e.g., Wilson’s disease). These conditions are frequently treatable and in certain cases also curable. Therefore, their recognition and treatment impact the outcomes of these patients.
Recent findings
Most current knowledge on this topic is based on cohort studies and single case reports. There are a few large studies mostly in the context of movement disorders in cerebrovascular disease and Wilson’s disease.
Summary
The management of movement disorders due to systemic disease is mostly achieved by treatment of the systemic conditions together with appropriate medical and surgical treatments for each manifestation. Specific considerations must be taken into account when managing the medications commonly used for movement disorders in the context of systemic disease compared to primary degenerative processes.
... Aside from treating the underlying cause, clonazepam has been reported as effective in some cases of opsoclonus-myoclonus syndrome. Other agents reported as effective in case reports include valproic acid, piracetam, topiramate, and reserpine [3,[77][78][79]. ...
... Intravenous clonazepam and 5-hydroxytryptophan have previously been reported as effective in case reports, though neither is commonly used presently. Reticular reflex myoclonus in the setting of hypoxia or uremia is often reversible with correction of the underlying metabolic derangement [79,80]. ...
... There are reports of alleviation of propriospinal myoclonus following surgical removal of a causative structural lesion. Assessment for such a structural lesion with spinal cord imaging is therefore important in proposing appropriate treatment [79,81,82]. ...
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.
... Hepatic and uremic encephalopathy are the most common metabolic derangements resulting in myoclonus and asterixis (Robottom and Weiner 2011). Since functional myoclonus is among the most common functional movement disorders, it is crucial to differentiate it from organic myoclonus (Mills and Mari 2015). ...
Extrapyramidal movement disorders comprise hypokinetic-rigid and hyperkinetic or mixed forms, most of them originating from dysfunction of the basal ganglia (BG) and their information circuits that have been briefly reviewed in part 1 of the papers on neuropathology and pathogenesis of extrapyramidal movement disorders. The classification of hyperkinetic forms distinguishes the following: (1) chorea and related syndromes; (2) dystonias (dyskinesias); (3) tics and tourette disorders; (4) ballism; (5) myoclonic and startle disorders; and (6) tremor syndromes. Recent genetic and molecular classification distinguishes the following: (1) polyglutamine disorders (Huntington’s disease and related disorders); (2) pantothenate kinase associated neurodegeneration; (3) Wilson’s disease and related disorders; and (4) other hereditary neurodegenerations without hitherto detected genetic or specific markers. The diversity of phenotypes is related to the deposition of pathologic proteins in distinct cell populations, causing neurodegeneration due to genetic and environmental factors, but there is frequent overlap between various disorders. Their etiopathogenesis is still poorly understood but is suggested to result from an interaction between genetic and environmental factors, multiple etiologies, and noxious factors (protein mishandling, mitochondrial dysfunction, oxidative stress, excitotoxicity, energy failure, chronic neuroinflammation), being more likely than one single factor. Current clinical consensus criteria have increased the diagnostic accuracy of most neurodegenerative movement disorders, but for their definite diagnosis, histopathological confirmation is required. A timely overview of the neuropathology and pathogenesis of the major hyperkinetic movement disorders is presented.
