🐱 New Study: Seizure Patterns, MRI & Antibodies in 35 Cats with Orofacial Involvement

Complex partial seizures with orofacial involvement in 35 cats: MRI changes, cerebrospinal fluid analysis, voltage-gated potassium channel antibodies and survival

Thomas Flegel, Kaspar Matiasek, Miriam Füsser, Lisa F Becker, Irene C Böttcher, Josephine Dietzel, Sarah Gutmann, Theresa Kalliwoda, Shenja Loderstedt, Carina Tästensen, Vivian Weiß, Leon P Schulte, Johanna E König

Background

Complex partial seizures with orofacial involvement (CPSOFI) in cats often present with facial twitching and salivation. Previous research has linked hippocampal necrosis and possible autoimmune limbic encephalitis to this seizure type, but it remains unclear whether these changes are causative or secondary. Voltage-gated potassium channel (VGKC) antibodies, particularly against LGI1 and CASPR2, have been implicated in limbic encephalitis, but their role in feline epilepsy is still debated. The study aimed to evaluate MRI hippocampal changes, cerebrospinal fluid (CSF) abnormalities, VGKC antibodies, and their relationship to survival outcomes in affected cats.

Methods

This retrospective study included 35 cats with CPSOFI presented between 2014 and 2022. Data collected included patient demographics, seizure types, MRI results, CSF findings, and VGKC antibody testing (LGI1, CASPR2). MRI scans were assessed for hippocampal T2/FLAIR hyperintensity and contrast enhancement. CSF was analyzed for nucleated cell count and protein levels. Survival data and the impact of potential prognostic factors (breed, sex, age at seizure onset, MRI findings, antibody status, prednisolone treatment) were evaluated using regression analyses.

Results
-MRI findings: 57.1% showed hippocampal hyperintensity; 37.1% had hippocampal contrast enhancement, always associated with hyperintensity. Most hyperintensities were bilateral.

-VGKC antibodies: Detected in 31.4% of cats; 10 with LGI1 and 1 with CASPR2 antibodies. Weak correlation with MRI findings (phi coefficient 0.12).

-CSF: Only 2 cats (5.7%) had abnormal cell counts; 1 had elevated protein.

-Treatment & survival: Most cats received phenobarbital-based anticonvulsant therapy, often combined with levetiracetam or diazepam; 26 also received prednisolone. Mean survival after diagnosis was 771 days; 63.6% of cats alive at study completion. No evaluated factor significantly predicted survival.

Limitations

The study was retrospective, with small sample size and subjective MRI interpretation. Lack of histopathology limited confirmation of hippocampal pathology. Differences in diagnostic timing may have influenced results. Antibody testing was limited to LGI1 and CASPR2, leaving other potential immune targets unexplored.

Conclusions

Cats with CPSOFI show variable MRI and antibody findings, with no consistent diagnostic marker across cases. VGKC antibodies, mostly LGI1, were detected in about one-third of cats, but with only weak association to hippocampal MRI changes. Neither MRI findings, CSF analysis, antibody status, nor treatment predicted survival, suggesting that CPSOFI remains diagnostically heterogeneous.

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