Subjects and the trial There were 70 stroke survivors without significant cognitive or
visual impairment in the study. The inclusion criteria was that the patient should be able to understand the information on the screen, grasp with their paretic hand, move their paretic limb against gravity and do the most basic movements to calibrate the game. Patients have a wide range of levels of abilities in their upper limb functions. None of these patients have previously played video games. They were asked to participate in a home-based rehabilitation programme using the Circus Challenge video games over a three month period. There were no requirements for the lower limb ability of the participants. Thus, the patients can either stand or sit to play the game.
Data were collected using a longitudinal design. According to the plan, each patient should have eight assessments in three months time. The first four assessments were ar- ranged weekly, and the following four were arranged fortnightly. For each patient, the first assessment gave the baseline dependence level only. Patients had the video game to play during their own time after the baseline assessment. In the following seven assess- ments, patients were visited by the therapists and both assessment game and assessment of the dependence level were carried out.
The video game Circus Challenge is a commercial game used to help patients recover
the upper limbs functions. It was produced for the company Limbs Alive by the profes-
sional video game studio Pitbull (http://www.pitbullstudio.co.uk) and computer scientists
from the project team. The video game contained a series of gaming scenarios within which players participate in a number of circus oriented activities by completing the re-
quired movements. The movements were designed and ordered by the therapists, in order
to help patients recover during an efficient and smooth process. Patients must move as
required by the game to score enough points to ensure successful completion of circus activities in the game.
The corresponding assessment game is called the Circus Challenge Assessment game. It is a simpler version of the full game. All the important movements in the commercial
game are included in the assessment game and ordered roughly according to the difficulty
levels. The data used in the model are from the assessment game rather than the full game. Further details about the data is in the following chapter.
The dependence level The dependence level means the level of dependency of inde-
pendency of the patients in their daily life. The measurement used to quantify the pa- tient’s dependence level is called Chedoke Arm and Hand Activity Inventory, or CAHAI for short (http://www.cahai.ca/). The medical team in the project decided to use
CAHAI-9 as the reference clinical standard. CAHAI-9 has nine different tasks from daily
activities, such as dial 999 and open a jar. This assessment is a fully validated measure of upper limb functional ability (S. Barreca (2005)). Each task uses seven points to quantify the patients in general. A score of 7 means the patient is fully independent with regards to that task, while a score 1 means that the patients is fully dependent. This gives us a measure from 9 to 63 to represent the dependency level of the patients.
According to the time from stroke to first first assessment, patients included in the study are split into two phases: chronic and acute. Chronic patients had their first stroke six months time ago. Some patients had stroke years ago. Acute patients had their stroke
within the last six months. Such separation is because of the different behaviour of
recovery from acute patients and chronic patients. It is well known in the literature (P. Langhorne (2009)) that generally, stroke patients recover with a relatively high speed immediately after the stroke, and slow down over time. After half a year to one year, nor- mally the recovery speed will reduce to a very low level. This is confirmed by this set of motion data. Figure 6.1 show the clinical CAHAI-9 values against time for acute patients and chronic patients respectively. Note that in the plots, the x axis for acute patients is the time since stroke, and for chronic patients is the visit time. This is because the time since stroke for chronic patients varies from a few months to a few years, which would
be difficult to visualize if using time since stroke. It is clear to see that the acute patients
0 5 10 15
0
20
40
60
weeks since stroke
CAHAI−9, r
a
w scores
(a) Acute patients
0 2 4 6 8 0 20 40 60 Visit CAHAI−9, r a w scores (b) Chronic patients Figure 6.1: Dependence level (CAHAI) against assessment time
The movements The therapists designed many movements in the commercial game.
The 40 most important movements were selected in the assessment game according to therapists experience. These movements can be categorized as four types:
Mirrored Two hands are required to do the same movement, at the same time, mirror each other with no phase lag.
In-phase Two hands are required to do the same movement, at the same time, but with a phase lag.
Sequential Two hands are required to do the same movement alternately. To be more specific, when one hand moves, the other hand is required to stay still with no
requirement about the posture. The order of which hand moves first does not effect
the result.
Coordinated Non-paretic hand is required to do a relatively complicated movement, while the paretic hand is required to stay still with a certain posture. This group has the hardest movements.
The most important movements are in the category “mirrored” and “in-phase”. This is
because the last two types may be too difficult for the patients to carry out. Thus the data
we have from the last two types of movements have less information than the ones from the first two types.