Through the Eyes of Neglect Patients: A Preliminary Eye-Tracking Study of Unilateral Spatial Neglect.

To the Editor: The incidence of unilateral spatial neglect (USN) has been described in up to 30%270% after an injury to the right hemisphere. USN is one of the strongest predictors of poor functional recovery, which can lead to more prolonged hospitalization and disrupt rehabilitation and recovery of functional disabilities after stroke, thus limiting independence. However, USN is not usually assessed in routine examinations after stroke. This fact could be motivated by the clinical heterogeneity of this syndrome and by the lack of standardized assessment tools. USN is assessed through functional or behavioral tests or by observation. Functional tests focus on functional impairments but do not provide information about the deficits, which makes them suitable for assessment but not for establishing customized intervention protocols. Behavioral tests are usually paper-and-pencil tasks that can be compensated, thus hiding the clinical condition of individuals with USN. Some of the behavioral tests, such as the Behavioral Inattention Test (BIT), evaluate the performance on daily activities such as phone dialing, coin sorting, or map navigation, in addition to performance on conventional cancellation tasks. However, the long duration of these tests can make them tiresome for many patients, especially for those with prominent attentional problems, and time-consuming for the clinical staff. The need for a therapist during the course of the test and its psycholinguistics requirements could also prevent the widespread use of these tests. USN has been reported to alter visual search, which has been posed as a cortically mediated behavior that involves attentional processing. Individuals with USN tend to compensate visual search capability and achieve balance on the neglected side with cervical rotations. Spatial and temporal patterns of visual search during cancellation, visuomotor, and visual search tasks have been proposed to improve examination. However, neutral stimuli may not be valid to assess USN, because emotional valence has been shown to affect the spatial imbalance of both performance speed and stability in USN. We present a novel technique based on eye-tracking technology to quantify visual search on a behavioral task that could overcome some of the limitations of the current clinical examination tools for USN. Case Report