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Angela Vincent - One of the best experts on this subject based on the ideXlab platform.
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hyperexcitability in acquired Neuromyotonia
2013Co-Authors: Corticomotoneuronal Function, Angela Vincent, Steve Vucic, Benjamin C. Cheah, Con Yiannikas, Matthew C. Kiernan, Correspondence ProfAbstract:Acquired Neuromyotonia encompasses a group of inflammatory disorders characterized by symptoms reflecting peripheral nerve hyperexcitability, which may be clinically confused in the early stages with amyotrophic lateral sclerosis. Despite a clear peripheral nerve focus, it remains unclear whether the ectopic activity in acquired Neuromyotonia receives a central contribution. To clarify whether cortical hyperexcitability contributes to development of clinical features of acquired Neuromyotonia, the present study investigated whether threshold tracking transcranial magnetic stimulation could detect cortical hyperexcitability in acquired Neuromyotonia, and whether this technique could differentiate acquired Neuromyotonia from amyotrophic lateral sclerosis. Cortical excitability studies were undertaken in 18 patients with acquired Neuromyotonia and 104 patients with amyotrophic lateral sclerosis, with results compared to 62 normal controls. Short-interval intracortical inhibition in patients with acquired Neuromyotonia was significantly different when compared to patients with amyotrophic lateral sclerosis (averaged short interval intracortical inhibition acquired Neuromyotonia 11.3 1.9%; amyotrophic lateral sclerosis 2.6 0.9%, P50.001). In addition, the motor evoked potential amplitudes (acquired Neuromyotonia 21.0 3.1%; amyotrophic lateral sclerosis 38.1 2.2%, P50.0001), intracortical facilitation (acquired Neuromyotonia 0.9 1.3%; amyotrophic lateral sclerosis 2.3 0.6%, P50.0001), resting motor thresholds (acquired Neuromyotonia 62.2 1.6%; amyotrophic lateral sclerosi
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Neuromyotonia: Clinical, Electrophysiological and Immunological Findings of 4 Cases (P02.244)
Neurology, 2013Co-Authors: Rosana Herminia Scola, Ana Miranda, Paulo José Lorenzoni, Cláudia Suemi Kamoi Kay, Angela Vincent, Lineu Cesar WerneckAbstract:OBJECTIVE: To analyze a series of patients with Neuromyotonia from neuromuscular disorders unit, Hospital de Clinicas da Universidade Federal do Parana. BACKGROUND: Neuromyotonia is a rare disease characterized by spontaneous and continuous muscle activity due to a disorder of the peripheral nerve hyperexcitability. Patients develop persistent muscle contraction, classically worsening after exercise. Electromyography is characterized by neuromyotonic discharges and about 40% of patients have detectable voltage-gated potassium-channel (VGKC) antibodies. DESIGN/METHODS: We studied four patients with Neuromyotonia, regarding the clinical, electrophysiological and immunological findings. RESULTS: The average age of onset of symptoms was 17.5 (7-35) years and there was no gender predilection. The average time between onset of symptoms and diagnosis was 9.5 (1-29) years. The patients had muscle twitching (100%), muscle hypertrophy and hyperhidrosis (100%), muscle cramps and stiffness (75%), pseudomyotonia (25%), weakness (75%), paresthesias (25%), dysphonia, dysphagia and dyspnea (25%) and central nervous system symptoms (25%). Family history and exogenous intoxication were negative. All patients had the dosage of anti-VGKC negative. Electrophysiological findings: myokymia and neuromyotonic discharges were found in all patients, douplets and multiplets in 100% and triplets in 50% of cases. The maximum intraburst frequency ranged from 70 to 200 Hz. Three patients were treated with carbamazepine and gabapentin with a good response to treatment. Three used phenytoin, and of these, two had a partial response and one had intolerance to the drug. One patient had epilepsy, one patient developed ulcerative colitis idiopathic, glomerulonephritis and eczema on the face and another one hypothyroidism, arthralgia and myalgia. CONCLUSIONS: The diagnosis of Neuromyotonia is accomplished primarily through clinical and electrophysiological findings. Electromyography often confirms diagnosis by the presence of neuromyotonic discharges. The dosage of anti-CKVD has a low sensitivity for the diagnosis of disease. The association with autoimmune diseases can be observed, as described in this series. Disclosure: Dr. Scola has received personal compensation for activities with Merck Serono as scientific advisor board. Dr. Paranhos has nothing to disclose. Dr. Lorenzoni has nothing to disclose. Dr. Kay has nothing to disclose. Dr. Vincent has received personal compensation for activities with Athena Diagnostics. Dr. Vincent has received royalty payments from Athena Diagnostics. Dr. Werneck has nothing to disclose.
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Corticomotoneuronal function and hyperexcitability in acquired Neuromyotonia
Brain : a journal of neurology, 2010Co-Authors: Steve Vucic, Angela Vincent, Benjamin C. Cheah, Con Yiannikas, Matthew C. KiernanAbstract:Acquired Neuromyotonia encompasses a group of inflammatory disorders characterized by symptoms reflecting peripheral nerve hyperexcitability, which may be clinically confused in the early stages with amyotrophic lateral sclerosis. Despite a clear peripheral nerve focus, it remains unclear whether the ectopic activity in acquired Neuromyotonia receives a central contribution. To clarify whether cortical hyperexcitability contributes to development of clinical features of acquired Neuromyotonia, the present study investigated whether threshold tracking transcranial magnetic stimulation could detect cortical hyperexcitability in acquired Neuromyotonia, and whether this technique could differentiate acquired Neuromyotonia from amyotrophic lateral sclerosis. Cortical excitability studies were undertaken in 18 patients with acquired Neuromyotonia and 104 patients with amyotrophic lateral sclerosis, with results compared to 62 normal controls. Short-interval intracortical inhibition in patients with acquired Neuromyotonia was significantly different when compared to patients with amyotrophic lateral sclerosis (averaged short interval intracortical inhibition acquired Neuromyotonia 11.3 ± 1.9%; amyotrophic lateral sclerosis 2.6 ± 0.9%, P < 0.001). In addition, the motor evoked potential amplitudes (acquired Neuromyotonia 21.0 ± 3.1%; amyotrophic lateral sclerosis 38.1 ± 2.2%, P < 0.0001), intracortical facilitation (acquired Neuromyotonia −0.9 ± 1.3%; amyotrophic lateral sclerosis −2.3 ± 0.6%, P < 0.0001), resting motor thresholds (acquired Neuromyotonia 62.2 ± 1.6%; amyotrophic lateral sclerosis 57.2 ± 0.9%, P < 0.05) and cortical silent period durations (acquired Neuromyotonia 212.8 ± 6.9 ms; amyotrophic lateral sclerosis 181.1 ± 4.3 ms, P < 0.0001) were significantly different between patients with acquired Neuromyotonia and amyotrophic lateral sclerosis. Threshold tracking transcranial magnetic stimulation established corticomotoneuronal integrity in acquired Neuromyotonia, arguing against a contribution of central processes to the development of nerve hyperexcitability in acquired Neuromyotonia.
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Ocular Neuromyotonia in a 15-year-old girl after radiation therapy.
Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus, 2008Co-Authors: Alexandre De Saint Sardos, Angela Vincent, Maryam Aroichane, Luis H. OspinaAbstract:A 15-year-old girl, previously treated with radiation, chemotherapy, and surgery for a posterior fossa medulloblastoma and parasellar metastasis at age 8, presented with a 10-month history of episodic horizontal diplopia. She was diagnosed with ocular Neuromyotonia and successfully treated with oral carbamazepine. Given the strong association between peripheral Neuromyotonia and the presence of autoimmune antivoltage-gated potassium channels, 1 the patient's blood was tested and found negative for these autoantibodies. This is the first time this has been verified in a person with ocular Neuromyotonia.
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Neuromyotonia and limbic encephalitis sera target mature Shaker-type K+ channels: subunit specificity correlates with clinical manifestations.
Brain : a journal of neurology, 2006Co-Authors: Kleopas A Kleopa, Bethan Lang, Angela Vincent, Lauren B Elman, Steven S. SchererAbstract:Autoantibodies to Shaker-type (Kv1) K+ channels are now known to be associated with three syndromes. Peripheral nerve hyperexcitability is the chief manifestation of acquired Neuromyotonia; the combination of Neuromyotonia with autonomic and CNS involvement is called Morvan's syndrome (MoS); and CNS manifestations without peripheral involvement is called limbic encephalitis (LE). To determine the cellular basis of these clinical manifestations, we immunostained mouse neural tissues with sera from patients with Neuromyotonia (n = 10), MoS (n = 2) or LE (n = 5), comparing with specific antibodies to relevant K+ channel subunits. Fourteen of 17 patients' sera were positive for Kv1.1, Kv1.2 or Kv1.6 antibodies by immunoprecipitation of 125I-alpha-dendrotoxin-labelled rabbit brain K+ channels. Most sera (11 out of 17) labelled juxtaparanodes of peripheral myelinated axons, co-localizing with Kv1.1 and Kv1.2. In the CNS, all sera tested (n = 12) co-localized with one or more areas of high Kv1.1, Kv1.2 or Kv1.6 channel expression: 10 out of 12 sera co-localized with Kv1.1 and Kv1.2 at spinal cord juxtaparanodes or cerebellar layers, while 3 out of 12 sera co-localized additionally (n = 2) or exclusively (n = 1) with Kv1.6 subunits in Purkinje cells, motor and hippocampal neurons. However, only sera from LE patients labelled the hippocampal areas that are enriched in excitatory, Kv1.1-positive axon terminals. All sera (17 out of 17) labelled one or more of these Kv1 subunits when expressed at the cell membrane of transfected HeLa cells, but not when they were retained in the endoplasmic reticulum. Again, LE sera labelled Kv1.1 subunits more prominently than did MoS or Neuromyotonia sera, suggesting an association between higher Kv1.1 specificity and limbic manifestations. In contrast, Neuromyotonia sera bound more strongly to Kv1.2 subunits than to Kv1.1 or Kv1.6. These studies support the hypothesis that antibodies to mature surface membrane-expressed Shaker-type K+ channels cause acquired Neuromyotonia, MoS and LE, and suggest that future assays based on immunofluorescence of cells expressing individual Kv1 subunits will prove more sensitive than the immunoprecipitation assay. Although more than one type of antibody is often detectable in individual sera, higher affinity for certain subunits or subunit combinations may determine the range of clinical manifestations.
Luc Van Ham - One of the best experts on this subject based on the ideXlab platform.
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Myokymia and Neuromyotonia in veterinary medicine: a comparison with peripheral nerve hyperexcitability syndrome in humans.
Veterinary journal (London England : 1997), 2013Co-Authors: An Vanhaesebrouck, Sofie Bhatti, Robin J.m. Franklin, Luc Van HamAbstract:Involuntary muscle hyperactivity can result from muscle or peripheral nerve hyperexcitability or central nervous system dysfunction. In humans, diseases causing hyperexcitability of peripheral nerves are grouped together under the term 'peripheral nerve hyperexcitability' (PNH). Hyperexcitability of the peripheral motor nerve can result into five different phenotypic main variants, i.e. fasciculations, myokymia, Neuromyotonia, cramps and tetany, each with their own clinical and electromyographic characteristics. This review focuses on the most commonly described expressions of PNH in veterinary medicine, i.e. myokymia and Neuromyotonia, in particular in young Jack Russell terriers. Data from 58 veterinary cases with generalized myokymia and Neuromyotonia were analyzed, including unpublished treatment and follow-up data on eight Jack Russell terriers from a previous study and seven additional Jack Russell terriers. A dysfunction of the potassium channel or its associated proteins has been found in many human syndromes characterized by PNH, in particular in generalized myokymia and Neuromyotonia, and is suspected to occur in veterinary medicine. Potential pathomechanisms of potassium channel dysfunction leading to signs of PNH are broad and include genetic mutations, antibody-mediated attack or ion channel maldistribution due to axonal degeneration or demyelination. A more accurate classification of the different PNH syndromes will facilitate a more rapid diagnosis and guide further research into natural occurring PNH in animals.
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Hereditary ataxia, myokymia and Neuromyotonia in Jack Russell terriers
The Veterinary record, 2012Co-Authors: An Vanhaesebrouck, Luc Van Ham, Robin J.m. Franklin, Sofie BhattiAbstract:A CONDITION characterised by hereditary ataxia, myokymia and Neuromyotonia has been described in the Jack Russell terrier breed (Van Ham and others 2004, Vanhaesebrouck and others 2010, Bhatti and others 2011). Myokymia (undulating muscle contractions that induce a rippling appearance of the overlying skin) is usually apparent at a very young age (several months to three years). Most dogs also show episodes of Neuromyotonia (sustained generalised muscle …
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Myokymia and Neuromyotonia in 37 Jack Russell terriers.
Veterinary journal (London England : 1997), 2010Co-Authors: Sofie Bhatti, An Vanhaesebrouck, Ingeborgh Polis, Iris Van Soens, Valentine Martlé, Clare Rusbridge, Luc Van HamAbstract:The clinical and clinicopathological characteristics, treatment and outcome of vermicular muscle contractions (myokymia) and generalized muscle stiffness (Neuromyotonia) in 37 Jack Russell terriers were evaluated retrospectively. Thirty dogs were affected by both disorders, whereas seven were presented with myokymia and never developed Neuromyotonia. Clinical signs started at the mean age of 8 months. Except for signs of myokymia and Neuromyotonia, clinical and neurological examination was normal in all dogs. Thirty dogs demonstrated typical signs of hereditary ataxia. Changes in serum chemistry included increased creatine kinase, aspartate aminotransferase and alanine aminotransferase concentrations. Electromyographic abnormalities, especially in muscles showing macroscopically visible myokymia, consisted of semirhythmic bursts of doublet, triplet, or multiplet discharges of a single motor unit. The amplitudes varied between 80 μV and 1 mV and occurred with an interburst frequency between 10 and 40 Hz and an intraburst frequency between 150 and 280 Hz. Most dogs were treated with a sodium channel blocker with variable results. Seven dogs died (most likely because of hyperthermia) or were euthanased during a neuromyotonic attack; 15 dogs were euthanased due to worsening of clinical signs, or lack of or no long-lasting effect of medication, and three were euthanased for unknown or unrelated reasons. Nine dogs were lost to follow-up and three were still alive 5-10.5 years after the start of clinical signs. In conclusion, young Jack Russell terriers with myokymia and Neuromyotonia should undergo a complete blood and electrophysiological examination. Long-term prognosis is not favourable.
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clinical and electrophysiological characterization of myokymia and Neuromyotonia in jack russell terriers
Journal of Veterinary Internal Medicine, 2010Co-Authors: An Vanhaesebrouck, Sofie Bhatti, Ingeborgh Polis, Iris Van Soens, Luc Poncelet, Luc Duchateau, S Diels, Luc Van HamAbstract: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.
Bethan Lang - One of the best experts on this subject based on the ideXlab platform.
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Neuromyotonia and limbic encephalitis sera target mature Shaker-type K+ channels: subunit specificity correlates with clinical manifestations.
Brain : a journal of neurology, 2006Co-Authors: Kleopas A Kleopa, Bethan Lang, Angela Vincent, Lauren B Elman, Steven S. SchererAbstract:Autoantibodies to Shaker-type (Kv1) K+ channels are now known to be associated with three syndromes. Peripheral nerve hyperexcitability is the chief manifestation of acquired Neuromyotonia; the combination of Neuromyotonia with autonomic and CNS involvement is called Morvan's syndrome (MoS); and CNS manifestations without peripheral involvement is called limbic encephalitis (LE). To determine the cellular basis of these clinical manifestations, we immunostained mouse neural tissues with sera from patients with Neuromyotonia (n = 10), MoS (n = 2) or LE (n = 5), comparing with specific antibodies to relevant K+ channel subunits. Fourteen of 17 patients' sera were positive for Kv1.1, Kv1.2 or Kv1.6 antibodies by immunoprecipitation of 125I-alpha-dendrotoxin-labelled rabbit brain K+ channels. Most sera (11 out of 17) labelled juxtaparanodes of peripheral myelinated axons, co-localizing with Kv1.1 and Kv1.2. In the CNS, all sera tested (n = 12) co-localized with one or more areas of high Kv1.1, Kv1.2 or Kv1.6 channel expression: 10 out of 12 sera co-localized with Kv1.1 and Kv1.2 at spinal cord juxtaparanodes or cerebellar layers, while 3 out of 12 sera co-localized additionally (n = 2) or exclusively (n = 1) with Kv1.6 subunits in Purkinje cells, motor and hippocampal neurons. However, only sera from LE patients labelled the hippocampal areas that are enriched in excitatory, Kv1.1-positive axon terminals. All sera (17 out of 17) labelled one or more of these Kv1 subunits when expressed at the cell membrane of transfected HeLa cells, but not when they were retained in the endoplasmic reticulum. Again, LE sera labelled Kv1.1 subunits more prominently than did MoS or Neuromyotonia sera, suggesting an association between higher Kv1.1 specificity and limbic manifestations. In contrast, Neuromyotonia sera bound more strongly to Kv1.2 subunits than to Kv1.1 or Kv1.6. These studies support the hypothesis that antibodies to mature surface membrane-expressed Shaker-type K+ channels cause acquired Neuromyotonia, MoS and LE, and suggest that future assays based on immunofluorescence of cells expressing individual Kv1 subunits will prove more sensitive than the immunoprecipitation assay. Although more than one type of antibody is often detectable in individual sera, higher affinity for certain subunits or subunit combinations may determine the range of clinical manifestations.
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Antibodies to voltage gated potassium channels in encephalitis
Journal of Neurology Neurosurgery and Psychiatry, 2002Co-Authors: Jackie Palace, Graham Williams, Bethan LangAbstract:Background: Raised levels of antibodies to voltage gated potassium channels (VGKC) have been found in acquired Neuromyotonia, Morvan's syndrome (Neuromyotonia with CNS involvement), and two patients with limbic syndromes. It is not yet clear how frequently VGKC antibodies are present in patients with CNS disorders, whether Neuromyotonia is always present, or whether they signify a good response to immunomodulation. Methods: Eleven serum samples from patients with unusual adult onset epilepsy syndromes and/or unexplained encephalitic/psychotic symptoms presenting to a general neurology clinic were screened for VGKC antibodies. Results were compared with sera from healthy and disease controls. Results: Five of 11 sera were positive at levels between 150 and 1050 pM (controls
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Autoimmune aetiology for acquired Neuromyotonia (Isaacs' syndrome)
Lancet (London England), 1991Co-Authors: S. Sinha, Bethan Lang, John Newsom-davis, Kerry R. Mills, N. Byrne, Angela VincentAbstract:Neuromyotonia is a rare disorder of unknown cause in which hyperexcitability of peripheral motor nerves leads to incapacitating muscle twitching, cramps, and weakness. We investigated an antibody-mediated mechanism for Neuromyotonia in a 24-year-old man with a 7-year history of severe disease unresponsive to pharmacological treatment. Two periods of plasma exchange each produced almost complete disappearance of symptoms for 2-3 weeks, and a highly significant decrease in recorded neuromyotonic discharges. Injection of the patient's plasma or purified IgG into mice significantly enhanced in-vitro resistance to d-tubocurarine at the neuromuscular junction of phrenic nerve-diaphragm preparations. This finding suggests that an increase in neurotransmitter release might result from an antibody-mediated reduction in the number of functional potassium channels that normally regulate nerve excitability. The demonstration of pathogenic IgG autoantibodies in acquired Neuromyotonia suggests that immunosuppressive treatment may be helpful in severe cases.
Roberto Furlan - One of the best experts on this subject based on the ideXlab platform.
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Acquired Neuromyotonia in thymoma-associated myasthenia gravis: a clinical and serological study.
European journal of neurology, 2019Co-Authors: Matteo Gastaldi, A De Rosa, Michelangelo Maestri, Elisabetta Zardini, S Scaranzin, Melania Guida, Paola Borrelli, Ottavia Eleonora Ferraro, Vito Lampasona, Roberto FurlanAbstract:BACKGROUND AND PURPOSE Acquired Neuromyotonia can occur in patients with thymoma, alone or in association with myasthenia gravis (MG), but the clinical prognostic significance of such comorbidity is largely unknown. The clinico-pathological features were investigated along with the occurrence of Neuromyotonia as predictors of tumour recurrence in patients with thymoma-associated myasthenia. METHODS A total number of 268 patients with thymomatous MG were studied retrospectively. Patients with symptoms of spontaneous muscle overactivity were selected for autoantibody testing using immunohistology for neuronal cell-surface proteins and cell-based assays for contactin-associated protein 2 (CASPR2), leucine-rich glioma inactivated 1 (LGI1), glycine receptor and Netrin-1 receptor antibodies. Neuromyotonia was diagnosed according to the presence of typical electromyography abnormalities and/or autoantibodies against LGI1/CASPR2. RESULTS Overall, 33/268 (12%) MG patients had a thymoma recurrence. Five/268 (2%) had Neuromyotonia, four with typical autoantibodies, including LGI1 (n = 1), CASPR2 (n = 1) or both (n = 2). Three patients had Netrin-1 receptor antibodies, two with Neuromyotonia and concomitant CASPR2+LGI1 antibodies and one with spontaneous muscle overactivity without electromyography evidence of Neuromyotonia. Thymoma recurrence was more frequent in those with (4/5, 80%) than in those without (28/263, 10%, P
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acquired Neuromyotonia in thymoma associated myasthenia gravis a clinical and serological study
European Journal of Neurology, 2019Co-Authors: Matteo Gastaldi, A De Rosa, Michelangelo Maestri, Elisabetta Zardini, S Scaranzin, Melania Guida, Paola Borrelli, Ottavia Eleonora Ferraro, Vito Lampasona, Roberto FurlanAbstract:BACKGROUND AND PURPOSE Acquired Neuromyotonia can occur in patients with thymoma, alone or in association with myasthenia gravis (MG), but the clinical prognostic significance of such comorbidity is largely unknown. The clinico-pathological features were investigated along with the occurrence of Neuromyotonia as predictors of tumour recurrence in patients with thymoma-associated myasthenia. METHODS A total number of 268 patients with thymomatous MG were studied retrospectively. Patients with symptoms of spontaneous muscle overactivity were selected for autoantibody testing using immunohistology for neuronal cell-surface proteins and cell-based assays for contactin-associated protein 2 (CASPR2), leucine-rich glioma inactivated 1 (LGI1), glycine receptor and Netrin-1 receptor antibodies. Neuromyotonia was diagnosed according to the presence of typical electromyography abnormalities and/or autoantibodies against LGI1/CASPR2. RESULTS Overall, 33/268 (12%) MG patients had a thymoma recurrence. Five/268 (2%) had Neuromyotonia, four with typical autoantibodies, including LGI1 (n = 1), CASPR2 (n = 1) or both (n = 2). Three patients had Netrin-1 receptor antibodies, two with Neuromyotonia and concomitant CASPR2+LGI1 antibodies and one with spontaneous muscle overactivity without electromyography evidence of Neuromyotonia. Thymoma recurrence was more frequent in those with (4/5, 80%) than in those without (28/263, 10%, P < 0.001) Neuromyotonia. Neuromyotonia preceded the recurrence in 4/5 patients. In univariate analysis, predictors of thymoma recurrence were age at thymectomy [odds ratio (OR) 0.95, 95% confidence interval (CI) 0.93-0.97], Masaoka stage ≥IIb (OR 10.73, 95% CI 2.38-48.36) and Neuromyotonia (OR 41.78, 95% CI 4.71-370.58). CONCLUSIONS De novo occurrence of Neuromyotonia in MG patients with previous thymomas is a rare event and may herald tumour recurrence. Neuronal autoantibodies can be helpful to assess the diagnosis. These observations provide pragmatic risk stratification for tumour vigilance in patients with thymomatous MG.
Paul Maddison - One of the best experts on this subject based on the ideXlab platform.
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Invited review Neuromyotonia
2006Co-Authors: Paul MaddisonAbstract:Neuromyotonia is a rare condition of spontaneous and continuous muscle fibre activity of peripheral nerve origin. It represents the more severe phenotype of peripheral nerve hyperexcitability, and when acquired is often associated with antibodies to voltage-gated potassium channels. There are no specific published electromyographic or clinical diagnostic criteria for this disorder. This review highlights the classical clinical, electrophysiological and immunological features of this disorder from what is currently known in the literature to date, and also from the author's own patients' studies. Neuromyotonia is best classified as a moderately severe disorder of peripheral nerve hyperexcitability, with electromyographic fea- tures of spontaneous, continuous, irregularly occurring doublet, or multiplet single motor unit (or partial motor unit) discharges, firing at a high intraburst frequency (30-300 Hz). Invariably, patients develop persistent muscle contraction, often worse following exercise. About 40% of patients with acquired Neuromyotonia will have detectable voltage-gated potassium-channel antibodies. Clinical, electrophysiological and immunological measurements are important in defining the phenotype of Neuromyotonia, and other, milder forms of peripheral nerve hyperexcitability. 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
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Strength-duration properties of peripheral nerve in acquired Neuromyotonia.
Muscle & nerve, 1999Co-Authors: Paul Maddison, John Newsom-davis, Kerry R. MillsAbstract:The strength-duration time constant (SDTC) of a myelinated axon is a property of the nodal membrane and is sensitive to changes in membrane potential. Strength-duration time constants for motor axons and cutaneous afferents of the median nerve were measured in 9 patients with acquired Neuromyotonia (NMT), a condition of peripheral nerve hyperexcitability, and 15 control patients. Mean motor axon time constants were significantly prolonged (344 ± 100 μs) in patients compared to healthy controls (264 ± 34 μs; P = 0.038), but sensory axon time constants were not significantly different. Motor axon time constants were longer than sensory axon time constants in 4 of the patients with Neuromyotonia, suggesting that the nodal membrane was depolarized by an ectopic focus at the site of nerve stimulation at the wrist, ionic conductances were altered at the node, or that the size of the node was increased, possibly as a result of immune-mediated damage. The anti–voltage-gated potassium channel antibodies thought to generate peripheral nerve hyperexcitability in acquired Neuromyotonia may be indirectly responsible for changes in motor axon nodal membrane properties. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 823–830,1999
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Acquired Neuromyotonia in a patient with spinal epidural abscess
Muscle & nerve, 1998Co-Authors: Paul Maddison, Angela Vincent, Kerry R. Mills, Nicholas D. Lawn, Michael DonaghyAbstract:We report a case of acquired Neuromyotonia in a patient with Staphylococcus aureus septicemia and a spinal epidural abscess. Autoantibodies to voltage-gated potassium channels, which are associated with acquired Neuromyotonia, were present during the patient's acute illness but became undetectable on clinical recovery. The spinal epidural abscess may have triggered the production of these specific autoantibodies, resulting in clinically and electromyographically detectable Neuromyotonia.
