BERLIN – Children with acute disseminated encephalomyelitis have a significantly increased risk of subsequent epilepsy when it occurs with oligoclonal bands in cerebrospinal fluid and seizures at presentation, Thomas Rossor, MD, reported at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.
But fortunately, the seizures of postacute disseminated encephalomyelitis (post-ADEM) epilepsy are relatively easy to control and not clinically devastating, said Dr. Rossor of Great Ormond Street Hospital, London.
Of the 12 who developed epilepsy in Dr. Rossor’s retrospective, multicenterof 74 children with ADEM, 11 were well controlled on one drug and 1 on two drugs.
Pediatric ADEM is usually monophasic with good clinical outcome, he said. But a benign course is not set in stone: Up to 40% of children experience seizures during the acute presentation. “In contrast,” Dr. Rossor said, “adult patients with relapsing-remitting multiple sclerosis have the same risk of developing epilepsy as the general population.” Among adults with cortical encephalitis, antibodies against myelin oligodendrocyte glycoprotein (MOG) have been associated with seizures and the need for antiepileptic medications, he added.
That finding was part of what spurred Dr. Rossor’s study, which aimed to identify predictors of relapse and post-ADEM epilepsy in children. The patients in the review had a median age of 4.5 years. All were tested for anti-MOG antibodies, and most (about 68%) were positive. Oligoclonal bands in cerebrospinal fluid (CSF) occurred in 22%. The median follow-up period was 5 years.
A total of 41% (n = 31) relapsed after the initial acute phase. Among these, the final diagnosis included multiphasic disseminated encephalomyelitis (n = 19); ADEM-optic neuritis (n = 3); and neuromyelitis optica spectrum disorder (n = 6).
Of the 74 patients, 16 (22%) had seizures during the acute phase, and 12 (16%) developed post-ADEM epilepsy at a median of 3 months. The most common clinical characteristics with post-ADEM epilepsy included oligoclonal bands (57% vs. 13%), anti-MOG antibodies (92% vs. 16%), and seizures at presentation (50% vs. 16%). When these were entered into a regression model, oligoclonal bands and initial seizures significantly predicted epilepsy, increasing the risk by 20.7 and 13.5 times, respectively.
Since relapse is known to be associated with post-ADEM epilepsy, Dr. Rossor first looked at relapse risk. He conducted a multivariate analysis that included several clinical characteristics: age, prodrome, increased CSF white cells and protein, oligoclonal bands, anti-MOG antibodies, and seizures both at presentation and after the acute phase.
Anti-MOG antibodies were significantly more common among the relapsed patients than among the monophasic patients (87% vs. 53%). Seizures at presentation also were more common among the relapsed patients (32% vs. 14%). These two factors were entered into a binary regression analysis; only anti-MOG antibodies remained significantly associated with relapse, increasing the risk fivefold (odds ratio = 5.4; P = .007).
Anti-MOG antibodies also were associated with both earlier and more relapses. Overall, 40% of anti–MOG-antibody–positive patients relapsed by 24 months. In contrast, only 20% of anti–MOG-antibody–negative patients had relapsed by 24 months, and this number remained steady throughout the follow-up period.
By 96 months, almost all the anti–MOG-antibody–positive patients had relapsed, and some experienced many relapses. “In the antibody-negative group, four patients did relapse, but they had relatively few relapses. In the antibody-positive group, some had relatively few relapses, but several had 15, 20, or 25 clinical relapses in the follow-up period,” he said.
Dr. Rossor and his coauthors had no financial disclosures.