Peer-reviewed veterinary case report
Cat with muscle twitching and stiffness diagnosed with myokymia
By Galano, Heather R et al.·Published in Journal of the American Veterinary Medical Association·2005·Veterinary Teaching Hospital, United States·View original on PubMed →
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Original publication title: Myokymia and neuromyotonia in a cat.
- Species:
- cat
Plain-English summary
A 6-year-old spayed female domestic shorthair cat was brought in for rhythmic muscle movements that had been happening for two weeks. The vet found that her limbs were stiff and showed signs of muscle wasting. Tests showed high levels of a muscle enzyme, and further examination revealed a specific muscle condition. Initially, treatments with carbamazepine and prednisone didn’t help, but the cat improved quickly after starting phenytoin. Six months later, her muscle activity had decreased significantly, although some symptoms remained.
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Abstract
A 6-year-old spayed female domestic shorthair cat was examined because of a 2-week history of rhythmic muscle movements. Physical examination revealed thoracic limb rigidity, contracture of the carpi, generalized muscle atrophy, and rhythmic rippling of the muscles of all 4 limbs. Results of a CBC and serum biochemistry profile were unremarkable other than high creatine kinase activity. Electromyography revealed unique high-frequency discharges, including rhythmic bursts of single motor unit potentials appearing as doublets (myokymia) and more prolonged bursts of nonrhythmic motor unit potentials with characteristic waning amplitudes (neuromyotonia). Histologic examination of muscle biopsy specimens revealed noninflammatory necrotizing myopathy with regeneration. The cat did not respond to treatment with carbamazepine or prednisone but improved rapidly after treatment with phenytoin was initiated. Six months after initial examination, electromyography revealed a substantial decrease in the amount of spontaneous activity in previously affected muscles. However, the myokymic and neuromyotonic discharges were still present, albeit with a substantial decrease in frequency.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/16313038/