Right hemisphere infarct patients and healthy controls: evaluation of starting points in cancellation tasks.

Abstract

Patients with visual neglect (VN) tend to start cancellation tasks from the right. This exceptional initial rightward bias is also seen in some right hemisphere (RH) stroke patients who do not meet the criteria of VN in conventional tests. The present study compared RH infarct patients' (examined on average 4 days post-stroke) and healthy controls' starting points (SPs) in three cancellation tasks of the Behavioural Inattention Test (BIT). Furthermore, task-specific guideline values were defined for a normal SP to differentiate the performance of healthy subjects from that of patients with subclinical inattention. Conventional tests indicated that 15 of the 70 RH infarct patients had VN. The control group comprised 44 healthy volunteers. In each task, the VN group started the cancellations mainly from the right. The non-neglect and healthy groups initiated most cancellations from the left, more so in the healthy group. Starting more than one BIT task outside the guideline value indicated pathological inattention, as this was typical among the VN patients, but exceptional among the healthy subjects. One-third of the non-neglect patients showed pathological inattention by starting more than one task outside the guideline value. Clinical assessment of VN should, therefore, include an evaluation of the SPs to detect this subtle form of neglect.