title: Photosensitivity in Dravet syndrome is under-recognized and related to prognosis.
abstract: To detect determinants for photoparoxysmal EEG response (PPR) in SCN1A-related Dravet syndrome (DS).
  
  
  
  Data were studied from nationwide medical histories and EEGs of DS-patients (n=53; 31 males, age 2-19years). Detailed questionnaires on visual stimuli were completed by parents (n=49).
  
  
  
  PPR was found in 22 patients (42%; median age 1.25yr), and repeatedly in 17%. PPR (17% of 249 intermittent photic stimulation (IPS)-EEGs) occurred more often with optimal IPS protocols (OR 2.11 [95%CI 1.09-4.13]) and in EEGs showing spontaneous epileptiform abnormalities (OR 5.08 [95%CI 2.05-12.55]). PPR-positive patients tended to be younger at first (p=0.072) and second seizure (p=0.049), showed severe intellectual disability (p=0.042), and had more often spontaneous occipital epileptiform abnormalities (p<0.001). Clinical sensitivity was reported in medical files in 22% of patients and by parents in 43% (self-induction 24%). Clinical or EEG proven visual sensitivity was detected in 65% of cases.
  
  
  
  Sensitivity to visual stimuli is very common in DS and more often noticed by parents than confirmed by EEG. Detection of PPR improves with repetitive tests using accurate IPS protocols.
  
  
  
  Photosensitivity is an important feature in DS and seems to be a marker of the severity of the disorder. Therefore repeated standardized IPS should be encouraged.
authors.affiliation: Department of Genetics, University Medical Center Utrecht, The Netherlands.
authors.forename: Nienke
authors.initials: N
authors.lastname: Verbeek
authors.affiliation: Department of Genetics, University Medical Center Utrecht, The Netherlands. Electronic address: d.kasteleijn@umcutrecht.nl.
authors.forename: Dorothée
authors.initials: D
authors.lastname: Kasteleijn-Nolst Trenité
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Stichting Epilepsie Instellingen Nederland, Zwolle/Heemstede, The Netherlands.
authors.forename: Merel
authors.initials: M
authors.lastname: Wassenaar
authors.affiliation: Department of Child Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands.
authors.forename: Jolien
authors.initials: J
authors.lastname: van Campen
authors.affiliation: Department of Genetics, University Medical Center Utrecht, The Netherlands.
authors.forename: Anja
authors.initials: A
authors.lastname: Sonsma
authors.affiliation: Stichting Epilepsie Instellingen Nederland, Zwolle/Heemstede, The Netherlands.
authors.forename: W Boudewijn
authors.initials: WB
authors.lastname: Gunning
authors.affiliation: Stichting Epilepsie Instellingen Nederland, Zwolle/Heemstede, The Netherlands.
authors.forename: Al
authors.initials: A
authors.lastname: de Weerd
authors.affiliation: Department of Genetics, University Medical Center Utrecht, The Netherlands.
authors.forename: Nine
authors.initials: N
authors.lastname: Knoers
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Stichting Epilepsie Instellingen Nederland, Zwolle/Heemstede, The Netherlands.
authors.forename: Willy
authors.initials: W
authors.lastname: Spetgens
authors.affiliation: Stichting Epilepsie Instellingen Nederland, Zwolle/Heemstede, The Netherlands.
authors.forename: Thea
authors.initials: T
authors.lastname: Gutter
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: Leijten
authors.affiliation: Department of Genetics, University Medical Center Utrecht, The Netherlands.
authors.forename: Eva
authors.initials: E
authors.lastname: Brilstra
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004831:Epilepsies, Myoclonic / Q000150:complications / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D020195:Epilepsy, Reflex / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D062550:NAV1.1 Voltage-Gated Sodium Channel / Q000235:genetics; D010775:Photic Stimulation
chemical_list: D062550:NAV1.1 Voltage-Gated Sodium Channel; C568242:SCN1A protein, human
keywords: PPR; Pattern stimulation; Photoparoxysmal EEG response; Prevalence; SCN1A; Self-induction