title: Visual function and compensatory mechanisms for hemianopia after hemispherectomy in children.
abstract: OBJECTIVE
  Little is known about the functional visual outcome of children after hemispherectomy. Several case reports have described an anomalous head posture (AHP) and exotropia (XT) contralateral to the side of early brain damage, as possible compensatory mechanisms (CMs) for homonymous hemianopia (HH). The aim of this study was to determine visual outcome and the prevalence of such CMs in hemispherectomized children.
  
  
  METHODS
  Patient files from all children who underwent hemispherectomy and had a postoperative ophthalmologic examination in the University Medical Center (UMC) Utrecht up to October 2012 were retrospectively reviewed. Preoperative and postoperative clinical information on visual fixation, visual acuity, visual fields, optic discs, head posturing, ocular alignment, and cognitive development was collected. Clinical characteristics were compared between children who developed CMs and those who did not.
  
  
  RESULTS
  Forty-five children (21 male) underwent a hemispherectomy (22 right) at a median age of 2.1 years. Median ophthalmologic follow-up was 2.3 years. After hemispherectomy, visual fixation was present in all children, and 87% of the examined children had a normal visual acuity or a mild visual impairment. All children who underwent a visual field measurement had an HH. Anomalous head posturing and continuous or intermittent XT contralateral to the side of hemispherectomy were found in 53% and 38% of children, respectively. Children with CMs had more frequently right-sided surgery and earlier onset of epilepsy, and they tended to be younger when they underwent hemispherectomy than children without.
  
  
  CONCLUSIONS
  Despite HH, the majority of children who undergo hemispherectomy have a good visual outcome. Furthermore, they frequently develop AHP and continuous or intermittent XT contralateral to the hemispherectomy as part of a coping strategy to optimize the functional visual field. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.
authors.affiliation: Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Koenraads
authors.forename: Denise C P
authors.initials: DC
authors.lastname: van der Linden
authors.forename: Monique M J
authors.initials: MM
authors.lastname: van Schooneveld
authors.forename: Saskia M
authors.initials: SM
authors.lastname: Imhof
authors.forename: P H
authors.initials: PH
authors.lastname: Gosselaar
authors.forename: Giorgio L
authors.initials: GL
authors.lastname: Porro
authors.forename: Kees P J
authors.initials: KP
authors.lastname: Braun
mesh_terms: D002675:Child, Preschool; D004827:Epilepsy / Q000601:surgery; D005260:Female; D005403:Fixation, Ocular; D006423:Hemianopsia / Q000209:etiology*; D038421:Hemispherectomy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014786:Vision Disorders / Q000209:etiology*; D014792:Visual Acuity; D014794:Visual Fields
keywords: Children; Compensation; Exotropia; Hemianopia; Hemispherectomy; Visual field