Delineation of the Feline Hippocampal Formation: A Comparison of Magnetic Resonance Images With Anatomic Slices

[Magnetic resonance imaging findings in 143 epileptic cats]

OBJECTIVE

Epilepsy is one of the more common chronic neurological diseases in cats in which MRI plays a key role in the diagnostic work-up. Hippocampal MRI changes are common in cats, however it is unclear whether these changes represent the reason or the consequence of the disease.The goal of the present study was the retrospective analysis of the MRI findings in a large cohort of epileptic cats.

MATERIAL AND METHODS

In total, 143 cats of 3 age groups (< 1 year, 1-6 years, and > 6 years) were included in the study. MRI findings were divided into 4 categories: normal, with extrahippocampal lesions, and hippocampal signal alterations with or without contrast enhancement. The prevalence and frequency of these MRI findings in the age groups were examined using chi-quadrat test and nominal regression model.

RESULTS

In approximately one half of the cats (49 %), MRI displayed normal findings. Extrahippocampal changes occurred in 18 % of the animals. Hippocampal alterations were present in 33 % of the cats. Hippocampal sclerosis was found histopathologically in all four MRI categories.

CONCLUSION AND CLINICAL RELEVANCE

Brain MRI was normal in approximately 50 % of the epileptic cats. Extrahippocampal changes are expected mostly in cats older than 6 years. The etiology of the hippocampal alterations is unclear in most cases. Further investigations are needed for a better understanding of the hippocampal signal alterations.