title: When left-hemisphere reading is compromised: Comparing reading ability in participants after left cerebral hemispherectomy and participants with developmental dyslexia.
abstract: OBJECTIVE
  We investigated reading skills in individuals who have undergone left cerebral hemispherectomy and in readers with developmental dyslexia to understand diverse characteristics contributing to reading difficulty. Although dyslexia is a developmental disorder, left hemispherectomy requires that patients (re)establish the language process needed to perform the language-based tasks in the nondominant (right) hemisphere to become readers.
  
  
  METHODS
  Participants with developmental dyslexia (DD; n = 11) and participants who had undergone left hemispherectomy (HEMI; n = 11) were matched on age and gender, and were compared on timed and untimed measures of single word and pseudo-word reading. The hemispherectomy group was subdivided into prenatal (in utero) and postnatal (>3 years) insult groups, indicating the timing of the primary lesion that ultimately required surgical intervention.
  
  
  RESULTS
  On an untimed reading measure, the readers with DD were comparable to individuals who had undergone left hemispherectomy due to prenatal insult, but both scored higher than the postnatal hemispherectomy group. Timed word reading differed across groups. The hemispherectomy prenatal subgroup had low average scores on both timed and untimed tests. The group with dyslexia had average scores on untimed measures and below average scores on timed reading. The hemispherectomy postnatal group had the lowest scores among the groups by a significant margin, and the most pronounced reading difficulty.
  
  
  CONCLUSIONS
  Patients with prenatal lesions leading to an isolated right hemisphere (RH) have the potential to develop reading to a degree comparable to that in persons with dyslexia for single word reading. This potential sharply diminishes in individuals who undergo hemispherectomy due to postnatal insult. The higher scores of the prenatal hemispherectomy group on timed reading suggest that under these conditions, individuals with an isolated RH can compensate to a significant degree.
authors: Department of Learning Disabilities, University of Haifa, Haifa, Israel.
authors: Tami
authors: T
authors: Katzir
authors: Department of Communication Sciences and Disorders, MGH Institute of Health Professions, Boston, Massachusetts, U.S.A.|McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A.
authors: Joanna A
authors: JA
authors: Christodoulou
authors: The Brain Recovery Project, Los Angeles, California, U.S.A.. sdebode@brainrecoveryproject.org.
authors: Stella
authors: S
authors: de Bode
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000627:therapeutic use; D016022:Case-Control Studies; D002648:Child; D032882:Comprehension; D004410:Dyslexia / Q000503:physiopathology*; D004827:Epilepsy / Q000188:drug therapy / Q000209:etiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D038421:Hemispherectomy; D006801:Humans; D007802:Language; D008297:Male; D011183:Postoperative Complications / Q000503:physiopathology*; D011932:Reading; D014825:Vocabulary; D055815:Young Adult
chemical_list: D000927:Anticonvulsants
keywords: Dyslexia; Epilepsy; Hemispherectomy; Reading; Right hemisphere