Visual attention in posterior stroke and relations to alexia.

Area of Science:

• Neuroscience
• Ophthalmology
• Cognitive Psychology

Background:

• Visual attention deficits are common after stroke, particularly in the right hemisphere.
• The impact of posterior cerebral artery (PCA) strokes on visual attention is less understood.
• Existing research often links attentional deficits to specific syndromes like visual agnosia or pure alexia.

Purpose of the Study:

• To characterize visual processing speed and apprehension span in patients with PCA stroke.
• To investigate the relationship between these attentional parameters and single-word reading ability.
• To explore how PCA lesions affect visual attention and reading, particularly in relation to pure alexia.

Main Methods:

• Eight patients with unilateral PCA strokes were selected based on lesion location.
• Visual attention was assessed using a whole report paradigm for hemifield-specific measurements.
• Processing speed and apprehension span were measured, and reading ability was evaluated.

Main Results:

• All patients exhibited reduced visual span contralateral to the lesion; four showed bilateral reductions.
• Six patients had isolated visual span deficits with unaffected processing speed.
• Impaired reading was observed only in patients with right hemifield visual span reduction, regardless of lesion lateralization or visual field deficits.

Conclusions:

• Unilateral PCA lesions can cause bilateral visual span deficits.
• Visual span reductions can be unilateral and occur independently of processing speed.
• Right hemifield visual span reduction is linked to reading impairment in PCA stroke patients.