Abstracts

Rationale: Eyelid myoclonia (EM) is an electroclinical event involving electrographic epileptiform discharges precipitated by active eye closure with associated rapid blinking, retropulsion of the eyeball and eyelid fluttering. EM is mostly described in association with Absence Epilepsy (EMA) and less often with Juvenile Myoclonic Epilepsy (JME). In our experience, EM can be seen in different generalized epilepsy (GE) syndromes. It is greatly underreported by parents and clinicians. Therefore its electroclinical characteristics and prevalence have not been well described. There is no data available on the natural course of EM or on its response to antiepileptic therapies. The goal of this study is to characterize the incidence and electroclinical characteristics of EM in our pediatric population with GE. Methods: This is a retrospective study at our tertiary care pediatric hospital, St. Christopher's Hospital for Children. Subjects were identified by searching the hospital's electronic medical record using the search terms: epilepsy, generalized epilepsy, absence, juvenile myoclonic epilepsy, seizure disorder, and idiopathic generalized epilepsy. Inclusion criteria were: age less than 21 years at time of treatment that were seen in clinic between June 2012 and December 2015; diagnosis of GE; and at least one routine or video EEG performed at our institution. GE diagnoses included the following: JME, Childhood Absence Epilepsy (CAE), Juvenile Absence Epilepsy (JAE), Generalized Epilepsy with Febrile Seizures Plus Syndrome (GEFS-plus), Myoclonic Astatic Epilepsy (MAE), Benign Myoclonic Epilepsy of Infancy (BMEI), and Idiopathic Generalized Epilepsy not otherwise specified (IGE-NOS). Patients with a diagnosis of focal epilepsy, Lennox-Gastaut Syndrome, Infantile Spasms, unspecified epilepsy, or those that a diagnosis of GE could not be established were excluded. Data included: age, gender, epilepsy diagnosis, and seizure types. Digital EEGs from subjects were reviewed by 3 independent reviewers for evidence of EM. Electrical and clinical characteristics of EM were described. Results: A total of 194 subjects fulfilling inclusion criteria were identified. Of these, 75 had CAE, 29 had JME, 39 had JAE, 5 had MAE, 4 had GEFS-plus, 1 had BMEI, and 40 had IGE-NOS. We evaluated 420 EEGs, of which 38 (9%) had electroclinical EM. Thirty-five subjects (18%) had electrographic EM and 25 (13%) had both electrographic and clinical EM. Of the 35 subjects with EM, 10 (29%) had CAE, 7 (20%) had JME, 11 (31%) had JAE, and 7 (20%) had IGE-NOS. EM was not identified in any of the subjects with MAE or BMEI. The incidences of EM in our GE population were: 13% in CAE, 24% in JME, 28% in JAE, and 18% in IGE-NOS. Neuroimaging, neurologic exam, and EEG background were normal in all subjects with EM. Electrographically, EM was characterized by diffuse spiky alpha with a biposterior predominance lasting up to 1 second following eye closure. Clinical signs were often subtle, involving eye closure, retropulsion of the eyeball, rapid eye movements or eyelid fluttering. Conclusions: EM occurs in various GE syndromes in addition to EMA. We characterized this seizure type, which has a distinctive electroclinical profile. In our study, EM occurs with a frequency as high as 18% in patients with GE, most commonly with CAE, JME, JAE, and IGE-NOS. This retrospective study adds to the currently limited knowledge of EM, increasing the understanding of the prevalence and electroclinical features of EM. By emphasizing awareness, further studies can be initiated into the natural course and treatment of EM. Funding: N/A