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| |  Noninvasive Brain Stimulation Enhances Recovery Potential of Visual Restoration Therapy in Hemianopia Patients: Presented at ANA By Crina Frincu-Mallos, PhD BALTIMORE, Md -- October 16, 2009 -- Neurovisual rehabilitation induces a significant improvement in the patients’ field of vision, when added to noninvasive brain stimulation in patients with hemianopia, according to a study presented here October 15 at the American Neurological Association (ANA) 134th Annual Meeting. “We present here preliminary evidence for efficacy of combining brain stimulation with neurovisual restoration therapy,” said Ela B. Plow, PhD, Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts. Visual restoration therapy (VRT) trains the so-called transition zone, a region of the affected hemifield that separates the blind zone from the intact area and can improve vision by an average 5 degrees. However, “critics argue that improvement from VRT does not alter function and is confounded by saccades,” said Dr. Plow. Yet, this “improvement in function cannot be explained by eye movements,” and the neural substrates for improvement “possibly include reorganisation of extravisual cortices,” she added. In a randomised, controlled, double-blind study, Dr. Plow and her team tested VRT in combination with brain stimulation in patients with hemianopia. They took this concept from stroke motor research, where it was observed that brain stimulation acts synergistically with forced use rehabilitation of an affected limb, attributed to an enhancement of the cortical excitability of the surviving motor networks. “Since the aim of VRT is forced use of the affected hemifield of vision,” argued Dr. Plow, “its efficacy could be enhanced using visual cortical stimulation.” The investigators hypothesised that combining VRT with transcranial direct current stimulation (tDCS) of intact and affected visual cortices, over 3 months, would enhance VRT’s efficacy by modulating plastic potential of residual neurons. Patients were randomly assigned to group 1 (VRT combined with tDCS) or group 2 (VRT combined with sham tDCS) and were trained using an eye-tracker for 30 minutes, twice daily, 3 days per week, for a 3-month period. Dependent measures included visual field tests, eye tracking, clinical measure of perimetry, functional magnetic resonance imaging (fMRI) during a visual motion task, a functional questionnaire, and subjective blind field drawing. After 3 months of training, accuracy on visual field test improved by 6.8 % in group 1, compared with only 2.3% in group 2. In addition, the visual field gain in the patients in group 1 was 5.2 degrees, compared with 1.93 degrees in group 2. The functional questionnaire demonstrated gain only on patients in group 1. The investigators also showed preliminary fMRI data, currently available in 3/7 patients, that confirmed neurovisual rehabilitation following training and showed reorganisation of extravisual areas. However, “transfer of visual field change from VRT to clinical perimetry is still not clearly evident,” Dr. Plow acknowledged. In addition to considering methodological refinements, the investigators said that more patients are needed to understand the validity of these preliminary results. [Presentation title: Neuro-Visual Rehabilitation Combined With Noninvasive Brain Stimulation to Enhance Function in Patients With Hemianopia. Abstract M-113]
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