Strange triggers for epilepsy

In an issue of The Veterinary Record, Pip Boydell from the Animal Medical Centre in Manchester wrote a letter regarding a trigger for epilepsy in a cat (see below). In this the trigger for seizures seemed to be rubbing or tapping the paw. He has had further anecdotal reports of a case triggered by scratching at the face — perhaps a trigeminal nerve neuropathy caused by herpesvirus, which resolved following treatment with interferon.

It reminded us of a series of letters on the subject of epilepsy which came from our readers back in 1996/97.

In one the fits seem to have been triggered by a daisy wheel printer (are these now a thing of the past?). It didn’t seem to be the sound but the vibrations which had an effect. Another reader mentions seizures in three elderly Birmans which seem to be linked to sharp noises such as a digital alarm and a daisy wheel printer. Another dropped a spoon in a ceramic feeding bowl close to the cat and induced a fit, and a further letter reported that the sound of breaking the foil seal on the packaging for a spot-on flea preparation had the same effect.

Alan Hopkins, a specialist who contributed at the time, said that while it is widely accepted that there are animals with epilepsy whose seizures can sometimes be induced by certain stimuli, the actual numbers of documented cases is surprisingly small. He recounted that as a student he remembered a cat whose seizures were induced by crinkling tin foil. He explained that, in human patients, the condition where seizures occur in response to an outside stimulus is known as reflex epilepsy or stimulus sensitive epilepsy.

Stimuli known to evoke seizures in people include visual, auditory, writing, reading, thinking (especially maths!) and eating. We are all aware of visually induced seizures as we are warned about strobe lighting in clubs or certain effects on TV.

Have you any more interesting cat cases to report? If so please email claire@icatcare.org

 

Case history

A four-year-old male neutered chocolate point Siamese cat was presented with a recent history of epileptiform seizures. MR scanning of the brain was reported to be unremarkable. The owner had noted that the seizures were invariably preceded by grooming of the left forepaw. Typically, after about 10 seconds of apparently normal licking, a brief extensor rigidity of the left forelimb and then immediately all four limbs and dorsiflexion of the neck was observed lasting for from three to five seconds, followed by a postictal period of general flaccidity of approximately one minute during which the cat was unresponsive to verbal or gentle tactile stimuli, then a sudden return to apparent normality.

Initially, it was thought that the licking might be a component of the seizure but rubbing or tapping the dorsum of the left forepaw with a finger nine or 10 times resulted in identical seizure episodes. This was consistent, although there appeared to be a refractory period of two to three hours before another attack could be induced. There was no apparent skin condition and no suggestion of pruritus or abnormal grooming behaviour. A routine haematology and biochemistry profile, and serology for feline leukaemia virus, feline immunodeficiency virus and feline infectious peritonitis were unremarkable. Further investigation was not performed for financial reasons.

The frequency of the episodes noted by the owner was at least once daily; medication with oral phenobarbitone elixir at a dose of 1mg/kg twice daily led to a degree of control, in that the observed seizure frequency dropped to twice a week. Telephone follow-up 14 months later indicated no change; the patient was lost to further follow-up.

Rub epilepsy has been described in human beings (Kanemoto and others 2001) and previously in domestic animals. It is of mild interest in that a number of animal seizures may involve what is described as an initial abnormal grooming behaviour. In some instances it may be that this behaviour is a cause rather than an effect.

Pip Boydell, Animal Medical Centre Referral Services, 511 Wilbraham Road, Manchester M21 0UB

Reference
Kanemoto K, Watanable Y, Tsuju T, Fukami M and Kawasaki J. (2001) Rub epilepsy: a somatosensory evoked reflex epilepsy induced by prolonged cutaneous stimulation. Journal of Neurology, Neurosurgery and Psychiatry70, 541—543

 

Could you cat suffer with sound-induced seizures? Take part in a survey being conducted by Davie Veterinary Specialists about sound-induced seizures in cats.

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