Visual field defects after posterior cerebral artery stroke can be improved by vision restoration training (VRT), but when combined with transcranial direct current stimulation (tDCS) which alters brain excitability, vision recovery can be potentiated in the chronic stage. To date the combination of VRT and tDCS has not been evaluated in post-acute stroke rehabilitation.
To determine whether combined tDCS and VRT can be effectively implemented in the early recovery phase following a stroke, we wished to explore the feasibility, safety and efficacy of an early intervention.
Open-label pilot study including a case series of seven tDCS/VRT versus a convenience sample of seven control patients (clinicalTrials.gov ID: NCT02935413).
Patients with homonymous visual field defects following a posterior cerebral artery stroke.
Seven homonymous hemianopia patients were prospectively treated with 10 sessions of combined tDCS (2mA, 10 daily sessions of 20 min) and VRT at 66 (±50) days on average post-stroke. Visual field recovery was compared with retrospective data of 7 controls, whose defect sizes and age of lesions were matched to the experimental subjects and who had received standard rehabilitation with compensatory eye movement and exploration training.
All seven patients of the treatment group completed the treatment protocol. Safety and acceptance were excellent, and patients reported occasional skin itching beneath the electrodes as the only minor side effect. Irrespective of their treatment, both groups (treatment and control) showed improved visual fields as documented by an increased mean sensitivity threshold in dB (decibel) in standard static perimetry. Recovery was significantly greater (p<.05) in tDCS/VRT patients (36.73 ± 37.0%) than in controls (10.74 ± 8.86).
In this open-label pilot study, tDCS/VRT in sub-acute stroke was safe, with excellent applicability and acceptance of the treatment. Preliminary effectiveness calculations show that tDCS/VRT may be superior to standard vision training procedures. A confirmatory, larger-sample, controlled, randomized and double-blind trial is now underway to compare real- vs. sham-tDCS supported visual field training in the early vision rehabilitation phase.