Visuospatial hemi-inattention following cerebellar/brain stem bleeding.

Neglect is a unilateral lack of responsiveness to stimuli caused by visuospatial hemi-inattention, a unilateral representation deficit and/or a unilateral hypokinesia. It results most frequently from right-hemisphere brain damage, particularly of the parietal lobe but also of the frontal cortex, the basal ganglia, the thalamus, and recently it has also been described after a cerebellar lesion. We report a patient with right-sided bleeding of the posterior inferior cerebellar artery, who developed a left-sided visual hemi-inattention. She had no visual field defects, yet she had problems detecting left-sided targets in visual extinction. Furthermore, she was impaired in detecting complex motion on the left side and targets in a fixation offset paradigm. Reactions to left-sided targets in covert shifts of attention were slowed in the invalid condition. Her text reading was impaired as she could not always find the initial word of the next line. However, she was aware of her deficit. Her visuoconstructive ability was normal and she gave no indication of tactile or acoustic extinction. As the cerebellar lesion was located in the right hemisphere and the inattention involved the left side of space, we suggest that the damage to the right brain stem led to a transient imbalance of the noradrenergic ascending activation system which may explain her hemi-inattention.