Prism adaptation as a two-week treatment.

Unilateral spatial neglect occurs frequently following a brain lesion in especially the right hemisphere (25-30% of all stroke patients, Appleros et al, 2002), resulting in a failure to report or respond to stimulation in contralesional hemispace. Prism adaptation is the most widely studied method to alleviate the symptoms of neglect. Effects of a single session of prism adaptation have been reported across clinical measures, but also in more daily situations, such as wheelchair navigation (Rossetti et al, 1999) and postural control (Tilikete et al, 2001). The current study will focus on the effects of an intensive programme of exposure to prism adaptation (i.e. daily exposure during two weeks) and whether more permanent changes in spatial awareness can be objectified. To assess the effects of prism adaptation in the proposed study, patients will receive either prism adaptation or sham adaptation. We expect longer-lasting, more general beneficial effects after prism adaptation compared to sham adaptation.

The current study will focus on the effects of an intensive programme of exposure to prism adaptation (i.e. daily exposure during two weeks) and whether more permanent changes in spatial awareness can be objectified. To assess the effects of prism adaptation in the proposed study, patients will receive either prism adaptation or sham adaptation. We expect longer-lasting, more general beneficial effects after prism adaptation compared to sham adaptation.

1. Baseline (T0);

2. After 1 week of PA (T1);

3. After 2 weeks of PA (T2);

4. 1 week after ending PA (T3);

5. 2 weeks after ending PA (T4);

6. 4 weeks after ending PA (T5);

7. 12 weeks after ending PA (T6).

The prism adaptation procedure will be similar to that employed by Rossetti et al (1998), with the exception that it will be repeated on a daily basis for 2 weeks. Prism adaptation will be performed with a pair of goggles fitted with wide-field point-to-point prismatic lenses, inducing a rightward optical shift of 10°.



Sham adaptation will be performed with a pair of goggles fitted with plain lenses (i.e. no optical shift).