Reconsidering the role of attention in optic ataxia: A case report of optic ataxia in visual neglect and extinction

Optic ataxia is a rare condition following dorsal visual stream lesions characterized by peripheral misreaching. This ‘pure’ visuomotor condition is claimed to be dissociable from attentional disorders, such as visual neglect and extinction. However, the relationship between optic ataxia, neglect and extinction is still controversial and recently it has even been suggested these conditions have a common attentional cause. In this single-case report, we investigated 67-year-old female patient E.B. with left visual neglect and extinction following right temporo-parietal and frontal strokes. Unlike most neglect patients, E.B. did not present left hemiparesis or left homonymous hemianopia. This unusual presentation allowed us to study, for the first time, the impact of left visual attentional disorders on reaching with both arms in both free and peripheral vision conditions. Specifically, we assessed whether patient E.B. would present the classic peripheral misreaching deficits reported in patients with optic ataxia. We found that patient E.B.’s reaching accuracy was significantly impaired, when compared to a gender and age-matched control sample (N=11), only in peripheral vision and only for targets presented in her neglected field, regardless of the hand used. Her performance was comparable to controls in free vision for both arms. This demonstrates that a patient with visual neglect and extinction also presents an ataxic field, a deficit typically described as optic ataxia. Our findings suggest that, at least in peripheral vision, attention and visuomotor deficits may be related which challenges long-standing claims of a dissociation between attentional disorders and optic ataxia.

Visual field improvement in neglect after virtual reality intervention: a case study

Objective. Studies on neuropsychological rehabilitation of visual field defects provide an inconsistent picture regarding the effectiveness of so-called "restorative approaches" in visual field recovery (VFR). During a current research project on the clinical evaluation of VFR - in combination with head mounted virtual reality displays (HMD) - a patient ("Patient 7") suffering from visual neglect was investigated. Although the concept of VFR is originally not intended for patients suffering from higher cortical regions (as in neglect), we hypothesized that due to the strong attention-demanding training situation in HMDs, neglect patients might benefit from these intervention procedures based on restorative approaches. Methods and Analysis. Patient 7 was examined perimetrically using a "Humphrey Field Analyzer", "Goldmann Perimetry" and our newly developed and validated eye-tracking supported perimetric methodology "Eye tracking based visual field analysis" (EFA). Based on these high resolution results from the EFA, the exact location of the transition area between intact and defect visual field of Patient 7 was assessed. Next, bright light stimuli were placed along this area in our newly developed HMD "Salzburg Visual Field Trainer" (SVFT). The aim was to stimulate neuroplasticity - according to the concept of restitutive approaches - in the corresponding cortical areas of the patient. Patient 7 trained with the SVFT for a time period of 254 days. In 6 appointments the objective and subjective rehabilitation progress was assessed. Results. Perimetric assessment with the EFA shows an expansion of Patient 7's visual field of 48.8% (left eye) and 36.8% (right eye) after 254 days of training with the SVFT. Individual areas in the patient's visual field show a visual improvement of approximately 5.5 to 10.5 degree of visual angle. Subjective self-report of Patient 7 additionally shows improvements in self-evaluation of up to 317% in visual field functionality compared to self-evaluation on the first assessment date. Conclusions. The results from Patient 7 indicate that patients suffering from visual neglect potentially benefit from a neuropsychological intervention with HMD based on the restorative concept of visual field recovery. However, further studies with large case numbers and a focus both on daily-life improvements and on a clear distinction between patients with lesions in earlier and higher cortical areas are needed to make empirically valid and generalizing statements about our findings.

Visual Perceptual Deficit Screening in Stroke Survivors: Evaluation of Current Practice in the United Kingdom and Republic of Ireland

PURPOSEVisual perceptual deficits are frequently underdiagnosed in stroke survivors compared to sensory vision deficits or visual neglect. To better understand this imparity, we evaluated current practice for screening post-stroke visual perceptual deficits.METHODSWe conducted a survey targeted at stroke clinicians involved in screening visual perceptual deficits across the United Kingdom and Republic of Ireland.RESULTSForty orthoptists and 174 occupational therapists responded to the survey. Visual perceptual deficit screening was primarily conducted by occupational therapists (94%), with approximately 75-100% of stroke survivors screened per month. Respondents lacked consensus on whether several common post-stroke visual deficits were perceptual or not. During screening, respondents primarily relied on self-reports and observation (94%), while assessment batteries (58%) and screening tools were underutilised (56%) and selected inappropriately (66%). Respondents reported lack of training in visual perception screening (20%) and physical/cognitive condition of stroke survivors (19%) as extremely challenging during screening.CONCLUSIONSVisual perceptual deficits are screened post-stroke at a similar rate to sensory vision or visual neglect. Underdiagnosis of visual perceptual deficits may stem from both reliance on subjective and non-standardised screening approaches, and conflicting definitions of visual perception held among clinicians. We recommend increased training provision and brief performance-based screening tools.

E-TAN, a technology-enhanced platform with tangible objects for the assessment of visual neglect: a multiple single-case study

Visual neglect is a frequent and disabling consequence of right brain damage. Traditional paper-and- pencil tests of neglect have limitations in sensitivity and ecological validity. The Baking Tray Task (BTT), instead, approaches real-life situations, because it requires participants to place 16 physical objects on a board. The number of objects placed on the left and right portions of the board provides a clinical index of visual neglect. Here we present E-TAN, a technology-enhanced platform which allows patients to perform an enhanced version of the BTT (E-BTT). This platform automatically determines the object locations on the board, and also records the sequence and timing of their placement. We used E-BTT to test 9 patients with right hemisphere damage, and compared their performance with that obtained by 115 healthy participants. To this end, we developed a new method of analysis of participants’ performance, based on the use of the convex hull described by the objects on the board. This measure provides an estimate of the portion of space processed by each participant, and can effectively discriminate neglect patients from patients without neglect. E-TAN allows clinicians to assess visuospatial performance by using a convenient, fast, and relatively automatized procedure, that patients can even perform at home to follow-up the effects of rehabilitation.