Characterizing the Clinical Features of LGI1-Ab Faciobrachial Dystonic Seizures
Faciobrachial dystonic seizures (FBDS) are a recognized immunotherapy-responsive disorder which feature characters that resemble traditional seizures. Unusual presentation and normal EEGs have led to them frequently being mislabeled as functional or psychiatric in origin. According to past research, MRI abnormalities accompanying FBDS are not well characterized but may help in diagnosis.
Mayo Clinic researchers, first author Eoin Flanagan, M.B., B.Ch., conducted a study to characterize the clinical features and MRI abnormalities of leucine-rich glioma-inactivated 1 (LGI1)-autoantibody (Ab) faciobrachial dystonic seizures. The study was recently published in the Neurology: Neuroimmunology & Neuroinflammation journal.
Researchers identified 48 patients from the Mayo Clinic clinical and serologic database with LGI1-Ab encephalopathy. Of these, 26 met inclusion criteria for the study with LGI1-Ab seropositivity and FBDS. In a separate analysis of all 48 patients initially identified, the MRIs of patients with and without FBDS were compared by two neuroradiologists blinded to the clinical details.
According to the study results, Ictal EEGs were normal in 20 of 23 patients assessed. Basal ganglia T1 and T2 signal abnormalities were detected in 11 patients, and included T1 hyperintensity alone, T2 hyperintensity alone, or both.
Improvement with immunotherapy was more frequent than with antiepileptic medications. A separate analysis of all 48 patients initially identified with LGI1-Ab encephalopathy showed that basal ganglia MRI abnormalities were present in 11 of 26 with FBDS but not present in those without FBDS. In contrast, mesial temporal MRI abnormalities were less common among those with FBDS.
Based on these results, researchers determined basal ganglia T1 hyperintensity is a clinically useful MRI biomarker of LGI1-Ab FBDS and suggests a basal ganglia localization.