Vertical neglect towards the lower space after bilateral parietal strokes - A case study.

While considerable knowledge has been acquired concerning the involvement of the parietal cortex in horizontal visuo-spatial attention, the understanding of its specific contribution to the vertical dimension remains limited. Here we present the exceptional case of a patient, who suffered from two consecutive ischemic strokes at the same location within the left and right Middle Cerebral Artery (MCA) territory, involving the superior parietal lobule, the supramarginal gyrus, and the angular gyrus. While the first left-hemispheric stroke led to a right-sided neglect, the consecutive stroke in the right hemisphere led to a left-sided neglect. In both cases, the horizontal visuo-spatial attentional bias resolved after a short time period. However, after the second stroke, the patient displayed a notable manifestation of vertical neglect for the right and the left lower visual space, as shown by means of a neuropsychological assessment with the Sensitive Neglect Test. Furthermore, video-oculography during Free Visual Exploration (FVE), comparing the patient's exploration behaviour against twenty age-matched healthy controls, confirmed the significant visuo-spatial attentional deficits for the lower visual space. In conclusion, the present case study illustrates that the parietal cortex controls visuo-spatial attention deployment towards the contralateral and, more prominently, towards the lower visual space. Therefore, the clinical evaluation of neglect symptoms should also take the vertical dimension into account.