title: Literacy after cerebral hemispherectomy: Can the isolated right hemisphere read?
abstract: OBJECTIVE
  Cerebral hemispherectomy, a surgical procedure undergone to control intractable seizures, is becoming a standard procedure with more cases identified and treated early in life [33]. While the effect of the dominant hemisphere resection on spoken language has been extensively researched, little is known about reading abilities in individuals after left-sided resection. Left-lateralized phonological abilities are the key components of reading, i.e., grapheme-phoneme conversion skills [1]. These skills are critical for the acquisition of word-specific orthographic knowledge and have been shown to predict reading levels in average readers as well as in readers with mild cognitive disability [26]. Furthermore, impaired phonological processing has been implicated as the cognitive basis in struggling readers. Here, we explored the reading skills in participants who have undergone left cerebral hemispherectomy.
  
  
  METHODS
  Seven individuals who have undergone left cerebral hemispherectomy to control intractable seizures associated with perinatal infarct have been recruited for this study. We examined if components of phonological processing that are shown to reliably separate average readers from struggling readers, i.e., phonological awareness, verbal memory, speed of retrieval, and size of vocabulary, show the same relationship to reading levels when they are mediated by the right hemisphere [2].
  
  
  RESULTS
  We found that about 60% of our group developed both word reading and paragraph reading in the average range. Phonological processing measured by both phonological awareness and nonword reading was unexpectedly spared in the majority of participants. Phonological awareness levels strongly correlated with word reading. Verbal memory, a component of phonological processing skills, together with receptive vocabulary size, positively correlated with reading levels similar to those reported in average readers. Receptive vocabulary, a bilateral function, was preserved to a certain degree similar to that of strongly left-lateralized phonological skills [3]. Later seizure onset was associated with better reading levels.
  
  
  CONCLUSIONS
  When cerebral hemispherectomy is performed to control seizures associated with very early (in utero) insult, it has been found that the remaining right hemisphere is still able to support reading and phonological processing skills that are normally mediated by the left hemisphere. Our results also suggest the existence of variability in individuals after hemispherectomy, even within groups having the same etiology and similar timing of insult.
authors.affiliation: Brain Recovery Project, Los Angeles, CA, USA. Electronic address: sdebode@brainrecoveryproject.org.
authors.forename: Stella
authors.initials: S
authors.lastname: de Bode
authors.affiliation: Department of Linguistics, University of Utrecht, The Netherlands.
authors.forename: Marine
authors.initials: M
authors.lastname: Chanturidze
authors.affiliation: Department of Neurosurgery, University of California, Los Angeles, CA, USA; Department of Psychiatry & Biobehavioral Sciences, University of California, Los Angeles, CA, USA; The Intellectual and Developmental Disabilities Research Centre, University of California, Los Angeles, CA, USA; The Brain Research Institute, University of California, Los Angeles, CA, USA; Mattel Children's Hospital, University of California, Los Angeles, CA, USA; David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Mathern
authors.affiliation: Linguistics Program, University of South Carolina, SC, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Dubinsky
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D000069279:Drug Resistant Epilepsy / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D038421:Hemispherectomy / Q000639:trends; D006801:Humans; D000067010:Literacy / Q000639:trends; D008297:Male; D011184:Postoperative Period; D011932:Reading; D055815:Young Adult
keywords: Cerebral hemispherectomy; Memory; Phonological processing; Reading; Seizure onset; Vocabulary