NEW ORLEANS—Epileptic seizures that do not respond to antiepileptic drugs but respond to immunotherapy may have an underlying autoimmune cause, according to data presented at the 2013 Annual Meeting of the American Neurological Association.
Researchers at the Mayo Clinic in Rochester, Minnesota, reviewed 29 patients with intractable, autoimmune-related epileptic seizures who were given a six- to 12-week trial of IV methylprednisolone (IVMP), IV immunoglobulin (IVIG), or both.
To determine whether immunotherapy could help diagnose and manage autoimmune epilepsy not caused by limbic encephalitis or other multifocal paraneoplastic disorders, Michel Toledano, MD, a neurologist at the Mayo Clinic, and colleagues reviewed 12 patients who had drug-resistant seizures alone and 17 patients who had drug-resistant seizures and other comorbidities.
Study participants were chosen on the basis of clinical presentation, imaging, detected neural antibodies, inflammatory CSF, or other characteristics suggesting inflammation. Response to the immunotherapy trial was defined as whether or not seizure frequency and severity decreased by 50% or more.
Eighteen patients (representing both groups) responded to the therapy; 10 persons became seizure-free. A total of 15 (52%) participants improved with either IVMP or IVIG; 43% of patients who did not respond to the first drug showed a response to the second drug.
Patients who responded positively to immunotherapy were more likely to have antibodies for neuronal plasma membrane antigens than persons who did not respond (78% vs 9%). In addition, 12 patients were seropositive for voltage-gated potassium channel-complex antibodies.
In all, 83% of patients who improved did so within four weeks of the initiation of therapy. Of the 18 participants who responded to immunotherapy, the researchers switched 13 individuals to long-term oral immunosuppressive therapy and followed them for six months. The positive response to therapy was sustained in 11 of these patients (85%).
“Although not diagnostic, response to an immunotherapy trial lends support to the diagnosis of autoimmune epilepsy in the right clinical setting and, as suggested in our study, justifies initiation of long-term immunosuppression,” Dr. Toledano said. Although the study was small, the data are intended to “provide clinicians with a logical management and treatment algorithm that has some basis on available evidence,” said Dr. Toledano.
IMNG Medical News