Director of Clinical Neurophysiology University of Texas Austin, Texas
Rationale: Sunflower syndrome is a rare photosensitive epilepsy characterized by seizures accompanied by hand-waving or repeated blinking while facing the sun. The heritability of Sunflower syndrome is unknown. Here, we describe two pairs of monozygotic twins with Sunflower syndrome with similarities and differences in presentation. Methods: Retrospective chart review was performed of four patients at Dell Children’s Medical Center, TX, and the University of Louisville, KY. EEGs, videos and MRIs were reviewed where available Results: Twins A/B are five-year-old biracial monozygotic females born at 28 weeks gestation with age-appropriate development. Twin A had a first generalized tonic-clonic seizure at age five years. MRI suggested right insular dysplasia. EEG showed right-predominant generalized spike- and polyspike-wave discharges. Epilepsy gene panel was negative. Twin B developed head drops a week later. MRI was normal, EEG showed left-predominant generalized spike- and polyspike-wave discharges. Both girls had developed episodes of turning towards the sun with behavioral arrest and eye blinking a year prior, disruptable by turning them away from the sun. Video EEG monitoring confirmed brief absence seizures with eyelid myoclonia, triggered by heliotropism. Twin B also had frequent spontaneous atonic (head drop) seizures. Neither twin exhibited hand-waving. Levetiracetam was ineffective in controlling seizures and twins were recently switched to valproic acid. Twins C/D are ten-year-old monozygotic Hispanic males, born at 30 weeks gestation, with age-appropriate development. Both developed hand-waving episodes at age four years, one six months prior to the other, initially misdiagnosed as tics. At the time of initial assessment at age six years, mother reported frequent events of hand-waving and unresponsiveness lasting seconds. EEGs of both twins showed 3-4 Hz generalized spike- and polyspike-wave discharges with activation during photic stimulation. Genetic testing was not performed due to financial constraints. Due to pre-existent behavior concerns, the twins were started on lamotrigine. Partial improvement was seen at initial doses before they were lost to follow-up. They re-presented two years later after twin C experienced a generalized tonic-clonic seizure. Twin D had experienced multiple four- to five-minute-long episodes of blank facial expression, blinking, dysphasia and enuresis unrelated to photic environment. Hand-waving was no longer seen, but both twins exhibited frequent episodes of staring into the sun and blinking repeatedly. Events were not controlled by levetiracetam but resolved after switching to valproic acid. Conclusions: This report describes features of Sunflower syndrome in monozygotic twins. Both pairs were concordant in epilepsy syndrome and had seizure onset within a short time of each other, consistent with published data on age of seizure onset as a familial trait, and epilepsy syndrome concordance rates in monozygotic twins. Overlapping but distinct ranges of seizure semiologies were seen within pairs. Whereas twins C/D had similar MRI and EEG findings, twins A/B showed differences in seizure semiology and MRI. Future research studying complex vs. Mendelian inheritance could help understand clinical heterogeneity in this syndrome. Funding: Please list any funding that was received in support of this abstract.: None.