title: Combining visual rehabilitative training and noninvasive brain stimulation to enhance visual function in patients with hemianopia: a comparative case study.
abstract: OBJECTIVE
  To standardize a protocol for promoting visual rehabilitative outcomes in post-stroke hemianopia by combining occipital cortical transcranial direct current stimulation (tDCS) with Vision Restoration Therapy (VRT).
  
  
  METHODS
  A comparative case study assessing feasibility and safety.
  
  
  METHODS
  A controlled laboratory setting.
  
  
  METHODS
  Two patients, both with right hemianopia after occipital stroke damage. METHODS AND OUTCOME MEASUREMENTS: Both patients underwent an identical VRT protocol that lasted 3 months (30 minutes, twice a day, 3 days per week). In patient 1, anodal tDCS was delivered to the occipital cortex during VRT training, whereas in patient 2 sham tDCS with VRT was performed. The primary outcome, visual field border, was defined objectively by using high-resolution perimetry. Secondary outcomes included subjective characterization of visual deficit and functional surveys that assessed performance on activities of daily living. For patient 1, the neural correlates of visual recovery were also investigated, by using functional magnetic resonance imaging.
  
  
  RESULTS
  Delivery of combined tDCS with VRT was feasible and safe. High-resolution perimetry revealed a greater shift in visual field border for patient 1 versus patient 2. Patient 1 also showed greater recovery of function in activities of daily living. Contrary to the expectation, patient 2 perceived greater subjective improvement in visual field despite objective high-resolution perimetry results that indicated otherwise. In patient 1, visual function recovery was associated with functional magnetic resonance imaging activity in surviving peri-lesional and bilateral higher-order visual areas.
  
  
  CONCLUSIONS
  Results of preliminary case comparisons suggest that occipital cortical tDCS may enhance recovery of visual function associated with concurrent VRT through visual cortical reorganization. Future studies may benefit from incorporating protocol refinements such as those described here, which include global capture of function, control for potential confounds, and investigation of underlying neural substrates of recovery.
authors.affiliation: Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ela B
authors.initials: EB
authors.lastname: Plow
authors.forename: Souzana N
authors.initials: SN
authors.lastname: Obretenova
authors.forename: Mark A
authors.initials: MA
authors.lastname: Halko
authors.forename: Sigrid
authors.initials: S
authors.lastname: Kenkel
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Jackson
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
authors.forename: Lotfi B
authors.initials: LB
authors.lastname: Merabet
mesh_terms: D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping; D004599:Electric Stimulation Therapy; D005133:Eye Movements; D005260:Female; D006423:Hemianopsia / Q000209:etiology / Q000534:rehabilitation*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010775:Photic Stimulation; D020521:Stroke / Q000150:complications; D014794:Visual Fields