Prism adaptation as a 2 week treatment

Lesions to the right temporo-parietal cortex typically result in neglect, a
disorder in which patients fail to respond to information in the contralesional
(mostly left) space. In severe cases, neglect patient act as if the left half
of their world does not exist. For example, a patient with neglect might ignore
food on the left half of their plate or fail to shave or make up the neglected
side of their face. It is now widely accepted that neglect is a complex,
heterogenous disorder that includes spatially lateralised deficits (e.g.
attentional biases) as well as non-lateralised deficits (e.g. sustained
temporal attention, temporal perception). Patients with neglect have been found
to have a poorer functional outcome compared to patients without neglect,
hence, rehabilitation of neglect has been the subject of many scientific
studies. In lab situations, with usually small groups of neglect patients,
prism adaptation appears to ameliorate the signs of neglect on a variety of
(neuropsychological) tests as well as some more *natural tasks*, such as
wheelchair navigation, or posture. These beneficial effects of prism adaptation
have been reported to last 2 hours up to one week after a single adaptation
session, and even up to 6 weeks following repetitive adaptation.

The current study will focus on the effects of an intensive programme of
exposure of prism adaptation (i.e. daily exposure during two weeks) and compare
these to sham adaptation.

Patients will be tested 6 times:
* baseline: at start of the study (T0)
* one week after starting adaptation (T1)
* two weeks after starting adaptation (T2)
* one week after ending adaptation (T3)
* two weeks after ending adaptation (T4)
* four weeks after ending adaptation (T5)
* twelve weeks after ending adaptation (T6)

During all session, neuropsychological neglect screening tests will be
presented along with a balance board test. During sessions 2, 4, and 6, tests
for posture and mobility will be performed and questionnaires will be filled
in. Nurses, physiotherapist, and the occupation therapist will fill out
questionnaires and observation scales also.

During prism adaption, patients wear prisms that shift their vision in one
direction (e.g. 10° to the right). They will initially misreach in the
direction of the prismatic shift (i.e. to the right), when they intend to point
directly to a target. After a few pointing movements, they quickly learn to
point accurately in the direction of the target to compensate for the shift in
vision. When the prisms are removed after multiple pointing trials
(approximately 100), patients will misreach in the direction opposite to the
prismatic shift.

Each patient will be seen 10 times during 2 weeks.
Patients will be tested 6 times:
* baseline: at start of the study (T0)
* one week after starting adaptation (T1)
* two weeks after starting adaptation (T2)
* one week after ending adaptation (T3)
* two weeks after ending adaptation (T4)
* four weeks after ending adaptation (T5)
* twelve weeks after ending adaptation (T6)

The risks of prism adaptation are negligible. Investigations of the possible
effect of treatment on neglect can only be assessed in a group of hemispatial
neglect patients.