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Movement Disorders Clinical Practice Jan 2023
PubMed: 36988999
DOI: 10.1002/mdc3.13602 -
Neurology India 2008The neuromuscular junction (NMJ) is a specialized synapse with a complex structural and functional organization. It is a target for a variety of immunological disorders... (Review)
Review
The neuromuscular junction (NMJ) is a specialized synapse with a complex structural and functional organization. It is a target for a variety of immunological disorders and these diseases usually respond well to immunotherapies. The understanding of the immunological basis of myasthenia gravis, the most common neuromuscular junction disorder, has improved in the recent years. Most patients have antibodies to the acetylcholine receptor (AChR), but around 10% have AChR antibodies that are only identified by novel methods, and up to 5% have muscle-specific kinase antibodies which define a different subgroup of myasthenia. The spectrum of antibodies and their pathophysiological aspects are being elucidated. Even though less common, Lambert Eaton myasthenic syndrome (LEMS) is important to recognize. The abnormality in LEMS is a presynaptic failure to release enough packets of ACh, caused by antibodies to the presynaptic voltage-gated calcium channels. More than half these patients have a small cell carcinoma of lung. Acquired neuromyotonia (NMT) is a condition associated with muscle hyperactivity. Clinical features include muscle stiffness, cramps, myokymia, pseudomyotonia and weakness. The immune mechanisms of acquired NMT relate to loss of voltage-gated potassium channel function. This review will focus on the important recent developments in the immune-mediated disorders of the NMJ.
Topics: Animals; Antibodies; Autoimmune Diseases; Central Nervous System Diseases; Humans; Myasthenia Gravis; Neuromuscular Junction; Potassium Channels, Voltage-Gated; Receptors, Cholinergic
PubMed: 18974557
DOI: 10.4103/0028-3886.43449 -
Movement Disorders : Official Journal... Jul 2016Adenylyl cyclase 5 (ADCY5) mutations is associated with heterogenous syndromes: familial dyskinesia and facial myokymia; paroxysmal chorea and dystonia;...
BACKGROUND
Adenylyl cyclase 5 (ADCY5) mutations is associated with heterogenous syndromes: familial dyskinesia and facial myokymia; paroxysmal chorea and dystonia; autosomal-dominant chorea and dystonia; and benign hereditary chorea. We provide detailed clinical data on 7 patients from six new kindreds with mutations in the ADCY5 gene, in order to expand and define the phenotypic spectrum of ADCY5 mutations.
METHODS
In 5 of the 7 patients, followed over a period of 9 to 32 years, ADCY5 was sequenced by Sanger sequencing. The other 2 unrelated patients participated in studies for undiagnosed pediatric hyperkinetic movement disorders and underwent whole-exome sequencing.
RESULTS
Five patients had the previously reported p.R418W ADCY5 mutation; we also identified two novel mutations at p.R418G and p.R418Q. All patients presented with motor milestone delay, infantile-onset action-induced generalized choreoathetosis, dystonia, or myoclonus, with episodic exacerbations during drowsiness being a characteristic feature. Axial hypotonia, impaired upward saccades, and intellectual disability were variable features. The p.R418G and p.R418Q mutation patients had a milder phenotype. Six of seven patients had mild functional gain with clonazepam or clobazam. One patient had bilateral globus pallidal DBS at the age of 33 with marked reduction in dyskinesia, which resulted in mild functional improvement.
CONCLUSION
We further delineate the clinical features of ADCY5 gene mutations and illustrate its wide phenotypic expression. We describe mild improvement after treatment with clonazepam, clobazam, and bilateral pallidal DBS. ADCY5-associated dyskinesia may be under-recognized, and its diagnosis has important prognostic, genetic, and therapeutic implications. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Topics: Adenylyl Cyclases; Aftercare; Child, Preschool; Female; Humans; Infant; Male; Movement Disorders; Pedigree
PubMed: 27061943
DOI: 10.1002/mds.26598 -
Journal of Neurology, Neurosurgery, and... Feb 1966
Topics: Adult; Electromyography; Facial Muscles; Female; Humans; Male; Middle Aged; Multiple Sclerosis; Myoclonus
PubMed: 5910576
DOI: 10.1136/jnnp.29.1.35 -
Clinical Case Reports Nov 2020Facial myokymia is a clinical sign that can occur as a manifestation of demyelinating lesions. As seen in our patient with multiple sclerosis, acute-onset continuous...
Facial myokymia is a clinical sign that can occur as a manifestation of demyelinating lesions. As seen in our patient with multiple sclerosis, acute-onset continuous facial myokymia can be indicative of an active lesion and can have localizing value.
PubMed: 33235796
DOI: 10.1002/ccr3.3135 -
The Journal of the American Osteopathic... Mar 2017Isaacs syndrome is a rare neuromuscular disorder characterized by chronic muscle stiffness, cramping, fasciculations, myokymia, and hyperhidrosis. Pathogenesis includes... (Review)
Review
Isaacs syndrome is a rare neuromuscular disorder characterized by chronic muscle stiffness, cramping, fasciculations, myokymia, and hyperhidrosis. Pathogenesis includes autoimmunity, paraneoplastic disorders, genetic predisposition, or toxin exposure. There is no known cure for Isaacs syndrome. This case report describes a patient who had been given the diagnosis of Isaacs syndrome and received osteopathic manipulative treatment to manage fascial and cranial dysfunctions and reduce nervous system hyperexcitability. Long-term decrease of myokymia and reduction of severity and frequency of exacerbations resulted.
Topics: Disease Progression; Electromyography; Follow-Up Studies; Humans; Isaacs Syndrome; Male; Manipulation, Osteopathic; Middle Aged; Rare Diseases; Risk Assessment; Severity of Illness Index; Time Factors; Treatment Outcome
PubMed: 28241332
DOI: 10.7556/jaoa.2017.035 -
Drugs in Context 2019Episodic ataxias (EAs) are characterized by recurrent, discrete episodes of vertigo and ataxia. EA1 and EA2 are the two most common forms. In the interictal interval,... (Review)
Review
Episodic ataxias (EAs) are characterized by recurrent, discrete episodes of vertigo and ataxia. EA1 and EA2 are the two most common forms. In the interictal interval, myokymia is typically present in EA1, whereas EA2 patients present with interictal nystagmus. Specific pharmacological therapies are available for EA1 and especially EA2. We briefly discuss the case of an Italian young man with EA2, with a novel mutation, who in our opinion is particularly illustrative for introducing the therapeutic approach. Acetazolamide could fully suppress EA episodes in our patient. We also provide a perspective review of the topic. 4-Aminopyridine is another valid treatment option. For EA1 (and for rarer EAs), the therapeutic possibilities are more limited. Carbamazepine is probably the treatment of choice for EA1, but the optimal treatment plan is unknown. A better understanding of the molecular processes involved in the mediation of EAs will lead to more specific and efficacious therapies for this still elusive group of disorders.
PubMed: 30891074
DOI: 10.7573/dic.212576 -
Journal of Clinical Medicine Sep 2020Paroxysmal symptoms are well-recognized manifestations of multiple sclerosis (MS). These are characterized by multiple, brief, sudden onset, and stereotyped episodes.... (Review)
Review
Paroxysmal symptoms are well-recognized manifestations of multiple sclerosis (MS). These are characterized by multiple, brief, sudden onset, and stereotyped episodes. They manifest as motor, sensory, visual, brainstem, and autonomic symptoms. When occurring in the setting of an established MS, the diagnosis is relatively straightforward. Conversely, the diagnosis is significantly more challenging when they occur as the initial manifestation of MS. The aim of this review is to summarize the various forms of paroxysmal symptoms reported in MS, with emphasis on the clinical features, radiological findings and treatment options.
PubMed: 32992918
DOI: 10.3390/jcm9103100 -
SAGE Open Medical Case Reports 2022Myokymia is defined as fluctuating hyperexcitability of muscle fibers caused by repetitive spontaneous contraction of motor units. Myokymia is generally benign with...
Myokymia is defined as fluctuating hyperexcitability of muscle fibers caused by repetitive spontaneous contraction of motor units. Myokymia is generally benign with self-resolution, although symptomatic treatment with benzodiazepines, anticonvulsants, and muscle relaxants can be used. Botulinum toxins can also be utilized, although they are mostly used for symptomatic facial myokymia. Here, we report two patients who developed continuous myokymia, resulting in secondary hypertrophy, stiffness, and discomfort in the affected muscles. The first patient had a history of a tethered spinal cord and developed continuous myokymia in the S1 and S2 radicular regions of the left leg. The second patient underwent radiation therapy for lung cancer and developed brachial plexopathy with abnormal activity in the muscles supplied by the musculocutaneous nerve in the right arm. Both patients experienced sleep disturbance, focal discomfort, and restlessness. The anticonvulsants and muscle relaxants were ineffective. Chemodenervation with botulinum A toxin was initiated using either onabotulinumtoxinA or abobotulinumtoxinA. Both patients experienced a substantial reduction in myokymia, with ongoing reversal of muscle hypertrophy and significant improvement in reported subjective symptoms. Treatment with botulinum toxins can be highly effective in patients with symptomatic segmental continuous hypertrophic myokymia and may be considered first-line therapy.
PubMed: 36406303
DOI: 10.1177/2050313X221137214 -
Journal of Veterinary Internal Medicine 2010Generalized myokymia and neuromyotonia (M/NM) in Jack Russell Terriers (JRTs) is related to peripheral nerve hyperexcitability syndrome in humans, a symptom complex...
BACKGROUND
Generalized myokymia and neuromyotonia (M/NM) in Jack Russell Terriers (JRTs) is related to peripheral nerve hyperexcitability syndrome in humans, a symptom complex resulting from diverse etiologies.
OBJECTIVE
Clinical and electrodiagnostic evaluation is used to narrow the list of possible etiological diagnoses in JRTs with M/NM.
ANIMALS
Nine healthy JRTs and 8 affected JRTs.
METHODS
A prospective study was conducted comparing clinical and electrophysiological characteristics in 8 JRTs affected by M/NM with 9 healthy JRT controls.
RESULTS
All affected dogs except 1 had clinical signs typical of hereditary ataxia (HA). In 6 dogs, neuromyotonic discharges were recorded during electromyogram. Motor nerve conduction studies showed an axonal neuropathy in only 1 affected dog. Compared with controls, brainstem auditory-evoked potentials (BAEP) showed prolonged latencies (P<.05) accompanied by the disappearance of wave components in 3 dogs. Onset latencies of tibial sensory-evoked potentials (SEP) recorded at the lumbar intervertebral level were delayed in the affected group (P<.001). The BAEP and SEP results of the only neuromyotonic dog without ataxia were normal.
CONCLUSIONS AND CLINICAL IMPORTANCE
The BAEP and spinal SEP abnormalities observed in JRTs with M/NM were associated with the presence of HA. Therefore, these electrophysiological findings presumably arise from the neurodegenerative changes characterizing HA and do not directly elucidate the pathogenesis of M/NM. An underlying neuronal ion channel dysfunction is thought to be the cause of M/NM in JRTs.
Topics: Animals; Dog Diseases; Dogs; Electrophysiological Phenomena; Female; Isaacs Syndrome; Male; Myokymia; Neural Conduction
PubMed: 20492485
DOI: 10.1111/j.1939-1676.2010.0525.x