Feline temporal lobe epilepsy: seven cases of hippocampal and piriform lobe necrosis in England and literature review

Case series summary Seven cases of feline hippocampal and piriform lobe necrosis (FHN) are described, with particular emphasis on clinical, radiographic and histopathological correlations. FHN is an uncommon acute epileptic condition resembling human autoimmune limbic encephalitis and temporal lobe epilepsy. Seizures are typically focal and feature uni- or bilateral orofacial or head twitching, hypersalivation, lip smacking, mydriasis, vocalisation and motionless staring, with inter-ictal behavioural changes such as unprovoked aggression and rapid running. Emerging evidence supports an autoimmune aetiology, although disruption of hippocampal architecture secondary to brain neoplasia has also been recognised. Most commonly, however, the underlying cause remains unknown. Diagnosis is achieved clinically and with brain MRI; electroencephalography and voltage-gated potassium channel-complex autoantibodies are currently the subject of research. Affected cats are frequently refractory to conventional antiepileptic treatment. Relevance and novel information Following a review of the literature, including potential complicating factors and comparisons with human medicine, the hippocampus and piriform lobe are proposed as the neuroanatomical localisation for focal seizures with orofacial involvement in cats, regardless of aetiology.