Hippocampal Necrosis in a Cat from Australia

Abstract

This paper reports findings from a feline case of hippocampal necrosis. A seven-year-old neutered female cat was seen with a history of behavioural change followed by complex focal seizures. The cat was severely pyrexic on presentation and anisocoria was present. It was treated with cooling, intravenous fluid, and phenobarbitone administration which was later changed to levetiracetam. An MRI was performed and revealed findings of a hypointense T1 and hyperintense T2 signal in the hippocampus and inferior temporal gyrus with mild gadolinium uptake, findings which were consistent with previous cases of hippocampal necrosis. The cat was witnessed to vomit and aspirate 24 hours after diagnosis leading to cardiac arrest and death. Postmortem examination revealed a subacute degenerative encephalopathy involving the hippocampus.

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

“…1,2,4,9,14,15 Affected cats should be treated promptly in the attempt of limiting the degree of hippocampal sclerosis, which represents a crucial element for pharmacoresistance. 4,18 According to some reports, 3,10,20,21 antiepileptic drugs (AEDs) seem to result in reduced seizure frequency and/or severity if associated with corticosteroids. Medications such as dexamethasone and prednisolone act as anti-inflammatory, anti-oedemigenous and immunosuppressive agents, and may be beneficial regardless of whether immune-mediated inflammation or neoplasia is suspected.…”

“…Feline hippocampal and piriform lobe necrosis (FHN) is an acute epileptic condition characterised by focal seizures consisting of uni-or bilateral orofacial or head twitching, hypersalivation, lip smacking, mydriasis, vocalisation and motionless staring lasting approximately 5-30 s. These cats usually show inter-ictal behavioural changes such as significant unprovoked aggression or rapid running. [1][2][3][4][5][6][7] Other less commonly reported signs are pyrexia, urinary retention, ataxia and generalised hyperaesthesia. 2,3,[8][9][10] Neurological examination is commonly unremarkable or non-specific; diagnosis is suspected based on clinical signs, supported by MRI and confirmed on post-mortem assessment.…”

“…[1][2][3][4][5][6][7] Other less commonly reported signs are pyrexia, urinary retention, ataxia and generalised hyperaesthesia. 2,3,[8][9][10] Neurological examination is commonly unremarkable or non-specific; diagnosis is suspected based on clinical signs, supported by MRI and confirmed on post-mortem assessment. It is currently unclear whether the lesions found are the primary cause of the seizures or whether it is the seizures themselves that result in necrosis.…”

Feline hippocampal and piriform lobe necrosis as a consequence of severe cluster seizures in two cats in Finland

“…Feline hippocampal necrosis (FHN), also known as necrosis of the hippocampus and piriform lobe, is recognized in several countries worldwide, with reports from Switzerland, Italy, Austria, United Kingdom, USA and Australia among others, and is considered an important aetiology for seizures [ 1 – 7 ], especially in feline complex partial seizures with orofacial automatism associated with hippocampal necrosis (FEPSO-HN) [ 8 ]. Interictal behavioural changes are regularly seen in addition to the seizures [ 1 – 4 , 8 ].…”