Santifort Koen M, Vanhaesebrouck An, Bashford James, Van Soens Iris
IVC Evidensia Small Animal Referral Hospital Arnhem, Arnhem, The Netherlands.
IVC Evidensia Small Animal Referral Hospital Hart van Brabant, Waalwijk, The Netherlands.
JFMS Open Rep. 2024 Dec 7;10(2):20551169241297768. doi: 10.1177/20551169241297768. eCollection 2024 Jul-Dec.
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.
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.
一只16岁已绝育的雌性家猫，患有用甲巯咪唑治疗的甲状腺功能亢进症，出现步态僵硬并逐渐发展为卧地不起的慢性进展性病史。神经系统检查发现持续存在过度肌张力并伴有肌束震颤，运动时加剧，且在全身麻醉期间持续存在。肌电图研究显示所有受试肌肉均有肌束震颤放电，以及复合重复放电、纤颤电位和正锐波。血液检查、尿液分析和腹部超声均未发现明显异常。肌肉活检的组织学检查未显示特定异常。做出了伴有肌束震颤的获得性神经性肌强直的临床诊断。苯妥英治疗带来了暂时改善，但过度肌张力复发，导致呼吸困难发作。就诊3周后选择实施安乐死。
据作者所知，这是猫获得性神经性肌强直的第二篇报道。与之前的报道不同，苯妥英治疗仅使症状得到部分和暂时改善。疾病随后的进展，包括呼吸困难和排尿困难的症状，导致决定对猫实施安乐死。在人类中，获得性神经性肌强直（艾萨克斯综合征）通常是由于对与电压门控钾通道相关的蛋白质产生自身免疫反应所致。在患有甲状腺疾病的人类中也有较少的报道。不能排除此处报道的猫与甲巯咪唑治疗或甲状腺功能亢进症之间的关联。
