AT ANA 2017
SAN DIEGO (FRONTLINE MEDICAL NEWS) – The sooner immunotherapy is started for faciobrachial dystonic seizures, the better, according to a retrospective review presented at the American Neurological Association annual meeting.
Only recently described, patients with faciobrachial dystonic seizures (FBDS) have frequent episodes – sometimes hundreds a day – of abrupt, involuntary, stereotypical movements lasting 1-5 seconds and typically involving one half of their face and the arm on the same side, such as a left-sided grimace and arm flex. It’s closely associated with antibodies against leucine-rich glioma, inactivated 1 (LGI-1), a protein that plays a role in synaptic transmission and myelination.
If left untreated, patients progress to limbic encephalitis with permanent cognitive impairment and other problems, sometimes within a few months. There’s surely an environmental trigger in susceptible people, but it hasn’t been identified, said study lead Dr. Julia Thompson, a consulting neurologist at King’s College Hospital, London.
“This is an autoimmune condition. It’s important to get onto it early; you’ve got to treat these seizures with immunotherapy and treat them fast,” she said.
A lot of the time, FBDS is probably mistaken for a movement disorder or tic, but tics aren’t typically dystonic, plus FBDS patients can’t suppress their movements and they don’t feel the buildup of tension, then release typical of tics. “If something doesn’t add up, test for the antibodies,” Dr. Thompson said.
Her team reviewed 103 cases culled from South Korea, Great Britain, Australia, and the United States, the largest cohort assembled to date. The median age was 64 years old; most patients were white, and 62% were men. There were no associations with tumors, and none of the seasonal variation typical of viral causes.
FBDS showed “a striking time-dependent response to immunotherapy. Prompt immunotherapy” stops the seizures and prevents brain damage, “maybe via inhibiting IgG1-mediated complement deposition,” Dr. Thompson said.
Antiepileptic drugs didn’t help much, but immunotherapy did; among patients who had immunotherapy, seizures stopped within 30 days in over half, and in 88% after 3 months. Only one patient with seizure cessation went on to develop cognitive impairment. For every day that immunotherapy was delayed, there was a 0.69% reduction in the probability of stopping the seizures. The window of opportunity appears to be short: among patients whose seizures weren’t terminated within 3 months, 56% progressed to cognitive impairment.
Immunotherapy varied greatly across the study centers, and included intravenous immunoglobulin, azathioprine, and mycophenolate, among other options that were generally given on a background of steroids.
“It became quite obvious that immunotherapy was the key,” but there weren’t enough patients to determine the optimal approach. Dr. Thompson and her colleagues are working to figure that out, as well as what triggers FBDS and its pathophysiology, she said.
Patients who just had seizures had almost exclusively LGI-1 IgG4 antibodies; those who had progressed to cognitive impairment had LGI-1 IgG1 antibodies. It’s unclear at this point what causes the subclass switch as patients progress.
Medial temporal lobe T2-hyperintensities and temporal and frontal lobe ictal EEG changes, as well as serum hyponatremia, were also found almost exclusively in patients with cognitive impairment.
Much remains to be learned about the condition.
There was no industry funding for the work, and Dr. Thompson didn’t have any disclosures.