Patients presenting with seizures who have no apparent epilepsy or other obvious cause may have an autoimmune condition, according to a study presented here at the 135th Annual Meeting of the American Neurological Association (ANA).
A recent retrospective study at Mayo Clinic, Phoenix, Arizona, found that a handful of patients with unidentifiable but intractable epilepsy had an autoimmune condition.
"The literature suggests the existence of autoimmune epilepsy, and that is what we found," said Matthew Hoerth, MD, Mayo Clinic, on September 14. "The condition is rare, based on our findings, but we wanted to check for it in case there are treatment options for these patients that we hadn't recognised."
About a third of all patients with epilepsy have no identifiable aetiology, Dr. Hoerth explained. Numerous inflammatory conditions are associated with seizures, including multiple sclerosis, lupus, antiphospholipid antibody syndrome, Sjogren's syndrome, Crohn's disease, sarcoidosis, central nervous system vasculitis, Grave's disease, steroid-responsive encephalopathy associated with autoimmune thyroiditis, and paraneoplastic syndromes. The problem, Dr. Hoerth added, is that seizures are a secondary and highly uncommon feature of these conditions. No adult autoimmune epilepsy syndrome presenting primarily with seizures has yet been well described.
"As a clinician, there is a real question as to when I need to worry about autoimmune epilepsy," Dr. Hoerth said. "We always have to wonder if we are catching all the patients. As it turned out, the answer is no."
The research team analysed the Mayo Clinic Hospital database in Phoenix and found 1,196 patients who were admitted between 2006 and 2009 with intractable epilepsy and positive autoantibodies but without other identified causes of seizures, of whom 11 qualified as cryptogenic. The search excluded patients with known autoimmune disorders that could account for seizures. Age at admission ranged from 23 to 72 years and time to diagnosis was about 11 months.
Of the 11 patients, 4 were men and 7 were women. All had frequent seizures; 4 had daily seizures, 4 had weekly seizures, and 3 had clusters of seizures. All of the patients were screened for malignancies and showed negative results.
Electroencephalograms in all 11 patients were consistent with focal epilepsy. Nine patients had paraneoplastic antibodies, 3 had rheumatologic antibodies, and 6 had multiple antibodies. Thyroperoxidase antibodies (n = 5) and voltage-gated potassium-channel antibodies (n = 5) were the most common antibodies seen. All 11 patients were given more than 2 antiepileptic agents.
Eight of the patients were treated with immune-modulating therapy, including intravenous methylprednisolone, intravenous immunoglobulin, plasmapheresis, oral prednisone, cytoxan, and azathiaprine. Two of the original 11 patients died, and 1 was given antiepileptics only because autoantibodies were not recognised at the time. Of the 8 patients treated with autoimmune agents, all had at least a 50% reduction in seizure frequency, although 1 patient later relapsed.
"Patients responded reasonably well to all of the treatments," Dr. Hoerth reported, "but response was not predictable or always long term. We obviously need to do more work in this area."
source: docguide
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