title: Epileptic spasms and early-onset photosensitive epilepsy in Patau syndrome: An EEG study.
abstract: BACKGROUND
  Patau syndrome, trisomy 13, is the third commonest autosomal trisomy. It is associated with a 25-50% prevalence of epilepsy, but detailed electroclinical descriptions are rare. The occurrence of early-onset photosensitivity has recently been reported in single patients.
  We collected electroclinical data on 8 infants (age range from 2 months to 3 years and 9 months, median: 17 months) with Patau syndrome referred for an EEG in our Clinical Neurophysiology Department between 1991 and 2011.
  
  
  METHODS
  All EEGs, case-notes, cytogenetic diagnosis and neuroimaging when available were reviewed; data on the occurrence of seizures, epileptiform discharges, photoparoxysmal response and their characteristics in terms of positive frequencies, latencies, grade and duration were noted and analysed.
  
  
  RESULTS
  Two patients had been previously diagnosed with epilepsy (one with tonic spasms and one with multiple seizure types). We found 3 patients with photosensitive myoclonic epilepsy (37.5%), and one with non-photosensitive myoclonic epilepsy. We also recorded non-epileptic myoclonic jerks in one patient known to suffer from epileptic spasms. Among photosensitive patients we found self-limited, Waltz's grade 2-4, spike-wave/polyspike-wave discharges in low, medium and high frequency ranges in two patients and in the high frequency range in the third patient, with latencies and duration from less than 1s to a maximum of 9s.
  
  
  CONCLUSIONS
  In our cohort of Patau syndrome patients, we found a high prevalence of spasms and photic-induced myoclonic jerks. Photosensitivity shows an unusual early age of onset.
authors.affiliation: Neurophysiology Department, Great Ormond Street Hospital, London, UK. Electronic address: carlotta.spagnoli@gmail.com.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Spagnoli
authors.affiliation: Neurophysiology Department, National Hospital for Neurology and Neurosurgery, London, UK.
authors.forename: Umaiyal
authors.initials: U
authors.lastname: Kugathasan
authors.affiliation: Genetics Department, Great Ormond Street Hospital, London, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Brittain
authors.affiliation: Neurophysiology Department, Great Ormond Street Hospital, London, UK.
authors.forename: Stewart G
authors.initials: SG
authors.lastname: Boyd
mesh_terms: D017668:Age of Onset; D001921:Brain / Q000503:physiopathology*; D002675:Child, Preschool; D025063:Chromosome Disorders / Q000453:epidemiology* / Q000503:physiopathology*; D002882:Chromosomes, Human, Pair 13; D004569:Electroencephalography; D004827:Epilepsy / Q000453:epidemiology* / Q000503:physiopathology*; D020195:Epilepsy, Reflex / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010775:Photic Stimulation; D015995:Prevalence; D012640:Seizures / Q000453:epidemiology / Q000503:physiopathology; D013036:Spasms, Infantile / Q000453:epidemiology / Q000503:physiopathology; D014314:Trisomy / Q000503:physiopathology*; D000073839:Trisomy 13 Syndrome
keywords: Chromosomal abnormalities; Infantile-onset; Myoclonic epilepsy; Patau syndrome; Photoparoxysmal response; Photosensitive epilepsy; Trisomy 13