Effects of noninvasive brain stimulation in cerebral stroke related vision loss
Background & Aims: Although vision loss is a very common and serious complication in cerebral stroke patients, there appears to be a mismatch in the number of studies establishing the potential of noninvasive brain stimulation modalities for post stroke vision loss compared to other complications of cerebrovascular accidents. This review aims to describe the current literature on noninvasive brain stimulation (NIBS) techniques in post cerebral stroke vision loss and suggests future considerations in this field.
Methods: Three independent reviewers conducted a systematic search in PUBMED database. We included all publications covering vision-loss after cerebral stroke (case reports, RCT, pilot studies). This search yielded six relevant papers that met our criteria.
Results: We found two case reports (1 tDCS, 1 TMS), one comparative case study (tDCS), and three randomized, controlled clinical pilot studies (all tDCS). No study applying tACS on stroke related vision loss fit our criteria. Our review shows that very few studies so far investigated non-invasive brain stimulation techniques as a treatment option in cerebral stroke related vision loss. The case reports as well as the small pilot studies;however, suggest a beneficial effect of applying tDCS over the primary visual cortex in addition to vision restoration training (VRT) in regaining parts of the visual field and accelerating the recovery time. These results are comparable and consistent with findings on stroke related motor and speech rehabilitation with the application of different NIBS protocols. A case report on repetitive TMS (1Hz) showed its potential use in down-regulation of visual cortical areas to cease visual hallucinations as a concomitant in visual field loss, also known as Charles-Bonnet-Syndrome.
Conclusion: Although studies are scarce and data are limited, we have found some evidence that NIBS-techniques have positive effects on the rehabilitation of visual field loss post cerebral stroke. More studies are needed to investigate mechanisms of action and proof of efficacy.