Abstracts

Rationale: Jeavons’ eyelid myoclonia with absences is considered predominantly a genetic epilepsy characterized by bursts of eyelid fluttering, with or without absence seizures, eye closure-provoked EEG paroxysms & photosensitivity. The clinical & electrographic features may be variable & genetic profiles are not often explored. We aimed to characterize these features in a large cohort with this epilepsy syndrome.Methods: A cohort was identified & recruited from the neurology clinics and EEG database at The Hospital for Sick Children (Toronto, Canada) between 2013-2015. Clinical features were reviewed from health records & personal interview. All available EEG recordings, neuroimaging, chromosomal microarrays for copy number variants & other genetic findings were reviewed.Results: 41 (29 female, 70%) patients were included for review. The median age of seizure onset was 4 years, median age of 13.5 years at last follow up. All patients described eyelid myoclonia & most had additional seizure types: absence 26 (63%), GTC 16 (39%), upper body myoclonus 14 (34%). Half had intellectual or learning disability. 8 (20%) had a first-degree relative with epilepsy. 14/32 (43%) had abnormal neuroimaging, including 3 with suspected malformations of cortical development. 38 patients were trialed on anticonvulsant medication with identifiable efficacies; 17 (45%) had a complete or near complete response, 21 (55%) had a partial or no response. Combination therapy of valproic acid and ethosuximide appeared to be the most consistently effective (3/3 had a complete response). Later age of seizure onset was associated with better response to medication. EEG review revealed a normal awake background rhythm in all but 2 patients (slow for age or poorly organized). All had normal sleep features. Eyelid myoclonia was recorded in 21 (50%), but without ictal changes seen in 4. Eyelid-closure induced epileptiform paroxysms were seen in all patients. The most common epileptiform morphology was polyspike-wave (25; 60%) & the median longest duration of the bursts was 3 seconds. There was a mix of anterior or posterior-leading bursts. Photoparoxysmal response (32; 78%) & hyperventilation activation (23; 56%) were seen. Focal epileptiform discharges were seen in 10; bilateral occipital discharges were seen in 4 of these. The majority (33; 75%) had clinical chromosomal microarray testing, of which 9/33 (27%) had possibly pathogenic copy number variants, including a deletion encompassing the CHD2 gene. 6 patients had specific epilepsy gene tests, which revealed possibly deleterious SCN9A & CNTNAP2 variants.Conclusions: This review of a large cohort of patients with eyelid myoclonia with absences characterizes an early-onset epilepsy with multiple seizure types, dominated by eyelid myoclonia & eye closure-induced EEG paroxysms. We observed better response with valproic acid/ethosuximide combination & with later age of onset. Family history & basic genetic testing support a strong genetic etiology. Further prospective study is necessary to uncover the genetic contributions & optimize management in this syndrome.