Abstract Details

Title Neuromyotonia: Clinical, Electrophysiological and Immunological Findings of 4 Cases

Topic Clinical Neurophysiology

Presentation(s) P02 - (-)

Poster/Presentation
Number 244

Objective

Background 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 DESIGN/METHODS: We studied four patients with neuromyotonia, regarding the clinical, electrophysiological and immunological findings.

Results 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 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.

Authors/Disclosures
Rosana H. Scola, MD (Hospital De Clinicas, Departamento De Neurolog) PRESENTER	Dr. Scola has nothing to disclose.
	No disclosure on file
Paulo J. Lorenzoni, MD (Neurology - Hospital De Clinicas - UFPR)	Dr. Lorenzoni has nothing to disclose.
Horacio C. Kaufmann, MD, FAAN (NYU Langone Health - NYU Dysautonomia Center)	Dr. Kaufmann has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Theravance. Dr. Kaufmann has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva Pharmaceuticals. Dr. Kaufmann has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Curasen Therapeutics. Dr. Kaufmann has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Lundbeck. Dr. Kaufmann has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for AskBio. Dr. Kaufmann has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for BioArctic. Dr. Kaufmann has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Sanofi. Dr. Kaufmann has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Spinger. The institution of Dr. Kaufmann has received research support from Biogen. The institution of Dr. Kaufmann has received research support from Vaxxinity. Dr. Kaufmann has received publishing royalties from a publication relating to health care.
Claudia S. Kay, MD	Dr. Kay has nothing to disclose.
	No disclosure on file
Lineu C. Werneck, MD (Universidade Federal do Parana)	No disclosure on file

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