Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism
Case summary A 16-year-old spayed female domestic shorthair cat with methimazole-treated hyperthyroidism presented with a chronic progressive history of a stiff gait progressing to recumbency. A neurological examination revealed continuous excessive muscle tone with myokymia, which exacerbated with...
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| Language: | English |
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SAGE Publishing
2024-12-01
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| Series: | Journal of Feline Medicine and Surgery Open Reports |
| Online Access: | https://doi.org/10.1177/20551169241297768 |
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| author | Koen M Santifort An Vanhaesebrouck James Bashford Iris Van Soens |
| author_facet | Koen M Santifort An Vanhaesebrouck James Bashford Iris Van Soens |
| author_sort | Koen M Santifort |
| collection | DOAJ |
| description | Case summary A 16-year-old spayed female domestic shorthair cat with methimazole-treated hyperthyroidism presented with a chronic progressive history of a stiff gait progressing to recumbency. A neurological examination revealed continuous excessive muscle tone with myokymia, which exacerbated with exercise and persisted during general anaesthesia. An electromyographic study revealed myokymic discharges in all tested muscles, as well as complex repetitive discharges, fibrillation potentials and positive sharp waves. Blood tests, urinalysis and abdominal ultrasound did not reveal significant abnormalities. A histological examination of a muscle biopsy showed no specific abnormalities. A clinical diagnosis of acquired neuromyotonia with myokymia was formulated. Phenytoin treatment resulted in temporary improvement, but excessive muscle tone recurred resulting in episodes of dyspnoea. Euthanasia was elected 3 weeks after presentation. Relevance and novel information To the best of the authors’ knowledge, this is the second report of an acquired neuromyotonia in a cat. In contrast with the previous report, treatment with phenytoin resulted in only partial and temporary improvement of signs. Subsequent progression of the disease, including signs of dyspnoea and dysuria, led to the decision to euthanase the cat. In humans, acquired neuromyotonia (Isaacs syndrome) is usually due to an autoimmune response to proteins associated with voltage-gated potassium channels. More rarely, it has also been described in humans with thyroid disorders. A link with methimazole treatment or hyperthyroidism in the cat reported here could not be excluded. |
| format | Article |
| id | doaj-art-5551e048c5d14e56a665fbed2a6f016c |
| institution | OA Journals |
| issn | 2055-1169 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | SAGE Publishing |
| record_format | Article |
| series | Journal of Feline Medicine and Surgery Open Reports |
| spelling | doaj-art-5551e048c5d14e56a665fbed2a6f016c2025-08-20T02:21:03ZengSAGE PublishingJournal of Feline Medicine and Surgery Open Reports2055-11692024-12-011010.1177/20551169241297768Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidismKoen M Santifort0An Vanhaesebrouck1James Bashford2Iris Van Soens3IVC Evidensia Small Animal Referral Hospital Hart van Brabant, Waalwijk, The NetherlandsVeterinary Department, Cambridge University, Cambridge, UKKing’s College Hospital NHS Foundation Trust, Denmark Hill, London, UKIVC Evidensia Small Animal Referral Hospital Hart van Brabant, Waalwijk, The NetherlandsCase summary A 16-year-old spayed female domestic shorthair cat with methimazole-treated hyperthyroidism presented with a chronic progressive history of a stiff gait progressing to recumbency. A neurological examination revealed continuous excessive muscle tone with myokymia, which exacerbated with exercise and persisted during general anaesthesia. An electromyographic study revealed myokymic discharges in all tested muscles, as well as complex repetitive discharges, fibrillation potentials and positive sharp waves. Blood tests, urinalysis and abdominal ultrasound did not reveal significant abnormalities. A histological examination of a muscle biopsy showed no specific abnormalities. A clinical diagnosis of acquired neuromyotonia with myokymia was formulated. Phenytoin treatment resulted in temporary improvement, but excessive muscle tone recurred resulting in episodes of dyspnoea. Euthanasia was elected 3 weeks after presentation. Relevance and novel information To the best of the authors’ knowledge, this is the second report of an acquired neuromyotonia in a cat. In contrast with the previous report, treatment with phenytoin resulted in only partial and temporary improvement of signs. Subsequent progression of the disease, including signs of dyspnoea and dysuria, led to the decision to euthanase the cat. In humans, acquired neuromyotonia (Isaacs syndrome) is usually due to an autoimmune response to proteins associated with voltage-gated potassium channels. More rarely, it has also been described in humans with thyroid disorders. A link with methimazole treatment or hyperthyroidism in the cat reported here could not be excluded.https://doi.org/10.1177/20551169241297768 |
| spellingShingle | Koen M Santifort An Vanhaesebrouck James Bashford Iris Van Soens Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism Journal of Feline Medicine and Surgery Open Reports |
| title | Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| title_full | Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| title_fullStr | Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| title_full_unstemmed | Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| title_short | Presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| title_sort | presumed acquired neuromyotonia of unknown cause in a cat with hyperthyroidism |
| url | https://doi.org/10.1177/20551169241297768 |
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