Segregation of Spontaneous and Training Induced Recovery from Visual Field Defects in Subacute Stroke Patients

Abstract

Whether rehabilitation after stroke profits from an early start is difficult to establish as the contributions of spontaneous recovery and treatment are difficult to tease apart. Here, we use a novel training design to dissociate these components for visual rehabilitation of subacute stroke patients with visual field defects such as hemianopia. Visual discrimination training was started within 6 weeks after stroke in 17 patients. Spontaneous and training-induced recoveries were distinguished by training one-half of the defect for 8 weeks, while monitoring spontaneous recovery in the other (control) half of the defect. Next, trained and control regions were swapped, and training continued for another 8 weeks. The same paradigm was also applied to seven chronic patients for whom spontaneous recovery can be excluded and changes in the control half of the defect point to a spillover effect of training. In both groups, field stability was assessed during a no-intervention period. Defect reduction was significantly greater in the trained part of the defect than in the simultaneously untrained part of the defect irrespective of training onset (p = 0.001). In subacute patients, training contributed about twice as much to their defect reduction as the spontaneous recovery. Goal Attainment Scores were significantly and positively correlated with the total defect reduction (p = 0.01), percentage increase reading speed was significantly and positively correlated with the defect reduction induced by training (epoch 1: p = 0.0044; epoch 2: p = 0.023). Visual training adds significantly to the spontaneous recovery of visual field defects, both during training in the early and the chronic stroke phase. However, field recovery as a result of training in this subacute phase was as large as in the chronic phase. This suggests that patients benefited primarily of early onset training by gaining access to a larger visual field sooner.

Increased Visual Sensitivity and Occipital Activity in Patients With Hemianopia Following Vision Rehabilitation

“…Some have involved repeated stimulation of visual deficits extending beyond the blind/sighted boarder and deep into the visual deficit ( Huxlin et al, 2009 ; Sahraie et al, 2013 ). These techniques have led to improvement measured both in psychophysical testing ( Sahraie et al, 2006 ; Raninen et al, 2007 ; Chokron et al, 2008 ; Huxlin et al, 2009 ; Sahraie et al, 2010 ) and more recently in visual fields ( Elshout et al, 2016 ; Bergsma et al, 2017 ; Cavanaugh and Huxlin, 2017 ), although there is skepticism that the results may reflect practice effects and do not translate to a meaningful improvement in visual function. To put the results in context, patients with incomplete hemianopia might expect a mean deviation −15 ± 2 (dBs) on Humphrey perimetry, whereas the intact field scores above zero when compared with healthy age-matched controls ( Sansal Gedik, 2007 ).…”

Rapid recovery from cortical visual impairment in a pediatric patient following vision training: A case study

“…In recent years, rigorous programs of vision restoration have been developed and tested for adults with CVI (Bergsma et al, 2017;Das et al, 2014;Huxlin et al, 2009;Jobke et al, 2009;Kasten et al, 1998;Melnick et al, 2016;Poggel et al, 2015;Saionz et al, 2020). The underlying premise of these interventions is that visual plasticity in healthy subjects can be engaged with training protocols that specifically target visual cortical structures with residual function (Awada et al, 2022;Bakhtiari et al, 2020;Das et al, 2014;Liu & Pack, 2017;Sabel et al, 2011).…”

Salzburg Visual Field Trainer (SVFT): A virtual reality device for (the evaluation of) neuropsychological rehabilitation

“…However, existing evidence for “training-induced neuroplasticity” in the human primary visual cortex is inconsistent. While some studies found a diminution of the blind field after intervention [ 6 – 9 ], other studies found no significant amelioration and attribute improvement after training to compensatory eye movements during perimetric pre-, post-, and follow-up assessments [ 10 – 13 ].…”