Magnetic Resonance Imaging of Feline Hippocampal Necrosis

Abstract

The clinical, neuropathologic, and magnetic resonance (MR) imaging features in four cats with necrosis of the hippocampus and piriform lobe are described. All cats had acute generalized seizures and behavioral changes including aggression, salivation, polyphagia, and disorientation. Routine hematologic, serum chemistry, and cerebrospinal fluid analyses were normal. MR imaging abnormalities were restricted to the area of the hippocampus and piriform lobe. The lesions were T2-hyperintense, T1-hypointense, and were characterized by various degrees of contrast enhancement. Lesions were consistent with necrotizing encephalitis. Two cats were euthanized and underwent postmortem examination within a week after MR imaging due to the lack of response to antiepileptic drug therapy and progressive neuropathy. The remaining two cats lived for about four months and were then euthanized because of persistent behavioral and neurologic signs; only one of these cats underwent postmortem examination with histopathologic examination. Histopathological findings were typical of severe, diffuse, bilateral symmetric necrosis, and degeneration of neurons in the hippocampus and piriform lobe, but an etiologic agent was not apparent. This apparently unique feline syndrome, now reported in Switzerland and Italy, has no known cause at this time.

Hippocampal Necrosis in a Cat from Australia

“…No abnormality was seen elsewhere in the brain. The findings of a hypointense T1 and hyperintense T2 signal in the hippocampus and inferior temporal gyrus with mild gadolinium uptake were consistent with changes reported in cats with hippocampal necrosis [6].…”

“…Hippocampal necrosis is reported to have a poor prognosis with high rates of death and euthanasia [1][2][3][4][5][6]. The outcome of this case is disappointing, but the management of this case was similar to the four reported surviving cases which were all managed with an anticonvulsant and supportive care [5].…”

“…Hippocampal necrosis is an infrequently reported MRI and postmortem finding in cats [1][2][3][4][5][6]. It has been predominantly associated with clinical signs of behavioral change and seizure activity and, to date, has been reported in cats from the UK, Switzerland, Italy, USA, and Austria [1][2][3][4][5][6].…”

“…It has been predominantly associated with clinical signs of behavioral change and seizure activity and, to date, has been reported in cats from the UK, Switzerland, Italy, USA, and Austria [1][2][3][4][5][6]. Cats with this disease have been reported to show a myriad of symptoms including salivation, behavioural change, complex focal seizures, facial twitching, lip smacking, chewing, retching, vomiting, diarrhoea, circling, excessive swallowing, and postural deficits or weakness [1][2][3][4][5][6]. The reported prognosis for this disease is very poor with one case series reporting 4 survivors out of 17 cases (23%) over a four-month period [4].…”

Novel approach to magnetic resonance imaging of epileptic dogs — T2 relaxometry of the brain with emphasised hippocampus

“…There are several works studying hippocampal changes particularly using quantitative MR methods, such as hippocampal volumetry in epileptic companion animals, supporting the importance and role of the hippocampal formation in feline (Fatzer et al, 2000;Brini et al, 2004;Schmied et al, 2008;Mizoguchi et al, 2014) and canine epilepsy (Vullo et al, 1996;Kuwabara et al, 2010;Milne et al, 2013). These studies described the qualitative MR findings of hippocampal abnormalities (sclerosis, atrophy and necrosis) in dogs and cats.…”