Unilateral neglect

Modular deficit

Unilateral hemineglect is characterised by lack or decrease of attention to stimuli and events on one side of the patient following a contralateral hemispheric lesion. In chronic patients neglect concerns the left hemispace. In extreme cases, patients do not react when they are spoken to from the left side, do not eat food on the left half of their plate, do not shave or make up the left half of their face, or read the left side of their newspaper. Formal testing of hemineglect consists of tests that require cancelling of items on a sheet of paper, copying or drawing of objects, line bisection, dichotic listening or simultaneous tactile stimulation, as well as behavioural and motor assessment (Azouvi et al., 2002, 2003; Perennou et al., 2002).

Hemineglect can affect, sometimes to a varying degree, visual, auditory, somatosensory and motor modalities (Barbieri and De Renzi, 1989).

In the visual modality, hemineglect does not only affect perception but also mental imagery. Bisiach and Luzzatti (1978) described the case of a patient whose hemineglect affected mental images of well-known Milanese landmarks. The perceptual and imagery aspects of visuo-spatial neglect can be affected independently, as demonstrated by the occurrence of selective deficits for extra-personal space, but not for visual images (Anderson, 1993) and a double dissociation between vision and visual imagery (Guariglia et al., 1993; Coslett, 1997). Left visuo-spatial neglect can affect also differently near and far space; selective deficits for one or the other aspect and double dissociations were reported (Guariglia and Antonucci, 1992; Cowey et al., 1994; Beschin and Robertson, 1997).