One of the symptoms of a right-hemisphere stroke in some people is spatial neglect. This condition impairs the ability to perceive objects in the left field of vision. People with spatial neglect who are given a page filled with words will only circle words on the right side as if the ones on the left side are not there. Spatial neglect makes functioning in society far more difficult. Imagine walking down a city street and seeing all the stores on both sides but only understanding what that stores on the right side mean. Even though the eyes look at the words “Italian Restaurant” to the left, the brain is unable to perceive the meaning of those letters.
Spatial neglect has many negative consequences on quality of life since many tasks involve understanding input from both sides of the body. Feeding, dressing, and hygiene are difficult. Falls are more common because patients are unable to orient the body in space correctly. Therapy also suffers because of the inability to focus on one side of the body. What makes spatial neglect so challenging to treat is that patients are often unaware that they have a deficiency. In the example above with the page of words, the patients do not even know there are words on the left side. So, they fail to realize that they have a deficiency in finding those words.
How prism adaptation therapy (PAT) works
Spatial neglect is a situation where the brain plays tricks on the patient. So maybe the solution to spatial neglect is to play tricks on the mind. That is the idea behind prism adaptation therapy, or PAT. A patient wears special goggles. These goggles produce an effect where an image appears shifted toward the right side, away from the area of neglect. The patient can fully see the object, but when she reaches for it, she can’t touch it. The patient then compensates for the prism effect by shifting focus further toward the area of neglect on the left. This practice increases the ability to orient toward the left and overcome the spatial neglect.
Past research with first-time stroke patients found that PAT increased attention to the neglected side and improved patients’ ability to perform self-care tasks. Whether people who have had multiple strokes would show similar benefits is still a question.
A research team from the United States sought to answer this question. They recruited 26 patients who recently had a recurrent stroke and who had spatial neglect. Half of the group was assigned to receive PAT therapy ten times for 20 minutes each. The other half received an equivalent amount of standard occupational therapy. The researchers found that PAT overall was more effective in improving spatial functions. Patients improved significantly between the second and fourth spatial tests and showed improved motor function.
Patients showed improvement using PAT
The results of PAT for spatial neglect rehabilitation are encouraging. Patients showed improvements in nearly all measures of spatial memory and motor functions. Patients also reported no adverse events, so there seems to be little drawback to trying PAT. It remains to be seen if PAT can replace standard occupational therapy or should be done in addition to it.
Because the number of subjects was small and the treatment duration was short, it is not known if all people will respond to PAT and how long the effects will last. The best advice for a stroke patient is to continue with standard therapy, but if possible incorporate PAT into a rehabilitation routine. The special PAT goggles are not commercially available, so, for now, patients will have to ask their therapists about trying this approach. Prism adaptation therapy is another tool for the recovering stroke patient to improve quality of life and the prospects for full recovery.
The first author of this study is Kimberly Hreha, Rehabilitation Medicine, University of Washington, Seattle, WA, USA.