BANGKOK – Cutaneous reactions to antiepileptic drugs in patients with chronic epilepsy suggest increased likelihood of an autoimmune element to their seizure disorder, Fernando Cendes, MD, PhD, reported at the International Epilepsy Congress.
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Dr. Fernando Cendes
“My recommendation based on our findings is that if you have a patient who has a history of skin reactions to AEDs [antiepileptic drugs], or who has psychosis, or who has a very strange response to antiepileptic medication – meaning that at some points they are refractory and at other points they are very well controlled – I think those patients are probably at risk for having an autoantibody,” he said at the congress sponsored by the International League Against Epilepsy.
Screening for autoantibodies in such patients is appropriate. However, there’s a caveat: “The thing is, we don’t have evidence that treating these autoantibodies with immunotherapy will have any benefit on seizure control in these patients. We don’t have that data yet, but we are looking into it,” according to Dr. Cendes, professor of neurology at the State University of Campinas (Brazil).
He presented a study of 221 consecutive adults with severe chronic refractory epilepsy as evidenced by a mean disease duration of nearly 29 years, with an average of 5.93 seizures per month. A total of 77% had a structural etiology for their epilepsy, in most cases hippocampal sclerosis. In 19% of patients, the etiology was unknown. Overall, 95% of subjects had focal epilepsy, and the remainder had generalized epilepsy. All underwent serum testing for a variety of antibodies against neuronal surface antigens that have been implicated in encephalitis, seizures, and/or psychosis. Those who tested positive then underwent confirmatory testing of their cerebrospinal fluid.
The impetus for this study, the neurologist explained, is that although it’s now well established that seizures are a common clinical expression of acute- and subacute-phase autoimmune encephalitis marked by neuronal autoantibodies, little is known about the relationship between chronic epilepsy and such antibodies.
Only five Brazilian patients with chronic epilepsy, or 2.2%, tested positive for autoantibodies, all of whom had mesial temporal lobe epilepsy with hippocampal sclerosis. This suggests a possible autoimmune etiology for hippocampal sclerosis. Three of the five patients had anti-N-methyl-D-aspartate receptor antibodies (anti-NMDA) and two had antiglutamic acid decarboxylate antibodies (anti-GAD). No one was positive for anti–leucine-rich glioma-inactivated 1 antibodies (anti-LGI1), anti–contactin-associated proteinlike 2 (anti-caspr2), anti-glutamate receptor antibodies (anti-AMPAr), or anti–gamma-aminobutyric acid receptor antibodies (anti-GABAr).
The autoantibody-negative and the much smaller autoantibody-positive groups didn’t differ significantly in terms of demographics, seizure frequency, disease duration, drug resistance, cognitive impairment, comorbid autoimmune conditions, or history of status epilepticus. Indeed, only two between-group differences were found: fluctuation in seizure control was an issue in 10.6% of autoantibody-negative and 40% of autoantibody-positive patients, and cutaneous adverse reactions to antiepileptic drugs were noted in 10.6% of antibody-negative and 60% of antibody-positive patients. Psychiatric comorbidities were present in 49.5% of autoantibody-negative patients as compared with 80% – that is, four of five – who were autoantibody-positive, a trend that didn’t achieve statistical significance.
Asked if he thinks the autoantibodies found in a small subset of patients with chronic epilepsy were a cause or an effect of repeated seizures for so long, Dr. Cendes replied, “That’s a very interesting question, and I don’t have an answer, actually. But if seizures trigger development of these antibodies – and remember, this population we’re talking about had many, many seizures over the years – I would expect antibodies to be more frequent than the figure we found.”
He reported having no financial conflicts regarding his study.
SOURCE: Watanabe N et al. IEC 2019, Abstract P004.