Abstracts

Rationale: Autoimmune epilepsy is an underlying inflammatory brain disease causing epilepsy refractory to conventional antiseizure drugs. It is increasingly recognized as a rare cause of intractable epilepsy which responds to immunotherapy. There have been prior studies on the acute management of autoimmune encephalitis for inpatients but less on subacute/chronic presentations in the outpatient setting. We seek to establish the prevalence of serum autoimmune antibodies in our cohort of intractable epilepsy patients without classic risk factors for epilepsy.

Methods: We enrolled a total of 14 candidates into our study who had intractable epilepsy, without classic epilepsy risk factors (head trauma with LOC, childhood seizures, developmental delay, structural lesions on MRI), and with reasonable suspicion of an underlying autoimmune etiology. APE2 scores were derived for each case. All patients had their blood serum sent to commercially available auto-antibody panels at Mayo Clinic Laboratories (EPS2 panel) and Moleculera Labs (D1R, D2L, lysoganglioside GM1, tubulin, CaMKII).

Limitations: Major limitations include the nonspecificity of symptoms and the rarity of autoimmune epilepsy. We also had a heterogenous cohort given that some patients had epilepsy for < 1 year and others had it for over a decade. This study may have false negatives given that we only tested the serum and not the CSF. Candidates in our study have limited resources, insurance coverage, and poor follow up. For these reasons, our cohort had various time courses of disease.

Results: 1/14 had definitive positive antibodies in the serum (positive for LGI1). 5/14 had detectable AchR, GAD65, Ca channel antibodies, but all titers were in the low range below positivity. 8/14 had a negative Mayo panel. 4 were positive for antibodies out of 6 who had APE2 score >= 4. 2 were positive for antibodies out of 8 who had an APE2 < 4. A statistically significant correlation was found with patients who had lower CaMKII and the presence of Mayo serum antibodies of any value (p=0.02, n=6). A statistically significant negative correlation was found between anti-tubulin levels and those with a history of status epilepticus (p=0.05, n=4). Higher titers of lysoganglioside GM1 antibodies and CaMKII were found in those with an APE2 < 4 not significant statistically. Higher titers of anti-D2L were detected in the presence of Mayo serum antibodies or with APE2 >= 4, but not statistically significant.

Conclusions: Testing for autoimmune autoantibodies in the serum of patients with intractable epilepsy but without classic epilepsy risk factors is generally low yield (6/14). However, patients with an APE2 score >= 4 were good candidates and likely to have some detected antibody on the Mayo serum panel. Interestingly, there was a statistically significant negative correlation between patients who had status epilepticus and anti-tubulin levels. There was also negative correlation between CaMKII and the presence of antibodies in the Mayo panel. Given the small sample size, it is difficult to draw any definite conclusions.

Funding: Please list any funding that was received in support of this abstract.: Astellas Research Institute of America.