Feline Hippocampal Necrosis and Temporal Lobe Epilepsy: A review of current literature and definitions.

Feline Hippocampal Necrosis (FHN) is a histopathological diagnosis first identified 25 years ago in domestic cats, and characterised by marked neuronal necrosis largely restricted to the hippocampus. FHN is often conflated with an overlapping condition, Hippocampal Sclerosis (HS). FHN does not represent a singular neurological condition, but rather a common endpoint of several disease entities including neoplasia, vascular disease and autoimmunity. The latter of these has been of particular interest in recent years with the discovery of limbic encephalitis and FHN associated with autoantibodies against leucine-rich glioma-inactivated 1 (LGI1) in domestic cats. Affected cats often present with characteristic seizures consistent with temporal lobe epilepsy. This review aims to explore the histopathological features of FHN and its relationship with HS, as well as the various presentations, aetiologies, imaging findings, treatment and outcomes reported in cats with FHN.