Epidemiological distribution of MRI‐based presumptive imaging diagnoses in a large general population of cats with suspected epileptic seizures

BACKGROUND: The reported prevalence of feline idiopathic epilepsy (IE) and presumptive imaging diagnoses based on magnetic resonance imaging (MRI) varies depending on factors such as differences between primary care versus referral study populations. METHODS: This retrospective, imaging-based study reviewed MRI data from cats with suspected epileptic seizures. Cases were categorised as follows: no lesions detected (IE, referring to cats aged 6 months‒7 years with recurrent epileptic seizures, and epilepsy or epileptic seizure of unknown aetiology [EuA] [i.e., cats not fulfilling IE criteria]) and structural lesion(s) detected (SL). Presumptive imaging diagnoses were classified according to the following aetiologies: presumptive intra-axial/extra-axial neoplasia, inflammatory, vascular, congenital, traumatic, metabolic/toxic and degenerative. RESULTS: Of 432 MRIs, 39% revealed SL, whereas 61% showed no structural lesions (of which 47% of cases were classified as IE and 53% were classified as EuA). Among cats with SL, presumptive imaging-based diagnoses included inflammatory diseases (25%), extra-axial neoplasia (19%), metabolic/toxic aetiologies (12%), congenital disorders (10%), lesions of unknown relevance (9%), intra-axial neoplasia (7%), trauma (5%), suspected hippocampal necrosis (5%), vascular events (4%), thiamine deficiency (2%) and degenerative diseases (2%). LIMITATIONS: This imaging-based study lacked histopathological confirmation and comprehensive clinical information. CONCLUSION: Nearly two-thirds of MRIs involving cats with suspected epileptic seizures showed no structural brain abnormalities.