Effectiveness of Virtual Reality Training on Unilateral Spatial Neglect After Stroke

STUDY DESIGN

The design of this study is a 1-week, assessor-blinded randomized controlled trial with a 1-week follow up.

MATERIALS

The HMD VR system 'Oculus Rift' (Oculus, LLS, US) is a low-cost HMD that fully integrates the user into the virtual environment by blocking out perception of the real-world. It includes a headset, two oculus touch controllers and two sensors. To power the Oculus Rift, a compatible laptop will be used. The "Oculus Rift" will assure a fully immersive virtual environment.

PROCEDURE

Pre-treatment assessment: First, eligible patients will be screened and assessed. For screening and assessment, patients will undergo 2 tests: a VR test and a conventional test. The patient will be seated in a (wheel)chair while performing the assessment tests, with one of the researchers present for safety. All patients will immediately complete the tests, without a try-out session. Instructions will be given in a consistent way and during the tests no feedback will be given.

For the VR-test, the HMD will be used. The VR test consists of 5 different tasks:

1. penguin search (1min)
2. smartphone search (1min)
3. apple examination (12 apples)
4. penguin extinction (10 times)
5. grabbing cubes (6 cubes)

For the conventional test, patients will need to perform the Behavioral Inattention test - conventional subtest (BITC), which consists of 6 different tasks:

1. line crossing
2. letter cancellation
3. star cancellation
4. figure and shape copying
5. line bisection
6. representational drawing

Once the assessment is completed, all patients will receive a standard care program provided by the rehabilitation hospital.

Intervention group:

Additionally, the intervention group will receive a VR training for 30 min consisting of various specific developed tasks for unilateral neglect training for a period of five consecutive days (one session a day). The VR training consists of the same 5 tasks used for the assessment. On the last day of the intervention and one week after, patients will be assessed again by completing the BITC test and the VR tasks.

Task 1: Penguin search: the patient has to search a penguin, which is randomly placed in the virtual environment. The patient has to aim for the penguin with this crosshair for a certain amount of time (until the loading bar is filled) in order to receive a point. The penguin is teleported to a new position afterwards. The subject has 2 minutes to gain as many points as possible. When the patient is not able to locate the penguin, arrows will indicate the direction of the penguin.

Task 2: Smartphone search: The Smartphone Search task is similar to the Penguin Search task. This time it takes place in a kitchen and the subject has to search for a smartphone on the kitchen counter. This kitchen counter is located in front of the subject. As in task 1, a crosshair is placed in the center of the camera canvas and the player receives points by aiming at the target. Like before, the subject has 2 minutes to gain as many points as possible. Like in the previous task, some arrows show up after ten seconds to help the subjects when they are not able to find the smartphone.

Task 3: Apple examination: In the Apple Examination task, the patient has to distinguish normal apples from distractors. The subject is placed in a grass landscape with 8 normal apples and 12 distractors. As in the previous tasks, a crosshair is attached to the canvas of the camera. The subject has to aim for the normal apples and press button A or X of the oculus controllers to get a point. The task ends when all normal apples are found.

Task 4: Penguin extinction: This task takes place in the same mountain environment as the Penguin Search task. In contrast with the other tasks, the subject doesn't have to search in the virtual environment, since everything takes place in the subject's field of view. There are three scenario's: either there is one penguin present on the right side, either there is one present on the left, or two penguins are present, one on each side. The subject has to say which scenario was presented by moving the thumbstick of the right or left oculus controller accordingly to the right (correct answer for scenario 1), to the left (correct answer for scenario 2) or upwards (correct answer for scenario 3). A point is gained for every correct answer. The task is completed when the subject has reached a score of thirty.

Task 5: Grabbing cubes: The last task is called Grabbing Cubes. Ten cubes are randomly placed on a table which is located in front of the player. The subjects have to grab the cubes and remove them from the table by dropping them on the ground. Grabbing an object is done by pressing the hand trigger of the left or right oculus controller. In order to complete the task, they have to remove all the cubes from the table.

Control group:

The control group will receive a placebo VR intervention. Patients in the control group will also use the HMD but they will look at another virtual environment with no specific tasks. The virtual environment represents a park outside where other avatars (hikers, joggers) are passing by. Patients will be looking at the environment for the same time as the VR training of the intervention group, i.e. 1 session a day for 5 days. On the last day of the intervention and one week after, patients will be assessed again by completing the BITC test and the VR tasks.

RANDOMIZATION

Participants will be randomly allocated to either the intervention group or the control group (1:1 ratio). Patients will be assigned to a group by block randomization.

STUDY ANALYSIS

Since heterogeneity between groups will be present at baseline, an ANCOVA analysis will be conducted to correct this matter. If significant changes are found at postintervention and follow-up, post-hoc analyses for multiple comparisons will be performed using the Bonferroni correction.