Pressure sensitive walkways and motion tracking devices provided reliable and quantitative measures of ambulation in multiple sclerosis patients, researchers said here
Researchers often rely on either visual inspection or motion capturing technology to determine how well a patient is walking. But the former is often inaccurate, and the latter can be expensive, said Jacob Sosnoff, PhD, of the University of Illinois in Urbana-Champaign, in a presentation at the European Committee for Treatment and Research in Multiple Sclerosis, held jointly this year with its North American counterpart.
Sosnoff and colleagues analyzed the walk of 86 ambulatory patients 6 months apart using GAITRite, a portable walkway sensitive to pressure. GAITRite -- whose products sell for $25,000 to $35,000 depending on the model, according to the company -- has previously been tested. In the current study, the researchers evaluated its reliability -- that is, whether results are similar in multiple tests during which the person's actual performance would not have changed substantially -- using intraclass correlation coefficients (ICC), which range from -1 to the perfectly correlated 1.
Five measures of walking were found to be reliable using the system:
- Gait velocity: 0.94, 95% CI .84-.97
- Functional ambulation profile: 0.94, 95% CI 0.90-0.96
- Cadence: 0.94, 95% CI 0.83-0.97
- Step time: 0.94, 95% CI 0.91-0.97
- Double support: 0.75, 95% CI 0.60-0.85
Of the patients in Sosnoff's study, 77% were female, and the median age was 50 (range 27-60). All of them had MS for at least six months, and 78% reported relapsing remitting MS. They had a self-reported disability of 3 on the patient determined disease steps scale (0-6). Patients were asked to walk 4.9 meters at their own pace on the GAITRite.
Walking impairment was reported as a primary limitation by 85% of study participants, said Sosnoff. "We want to target gait in rehabilitation, but obviously, for us to target that, we need to have valid and reliable measures."
Currently, functional abilities in MS patients are most often assessed with the Expanded Disability Status Scale (EDSS), a categorical measure that relies on subjective evaluations that may vary between raters, and yet is insensitive to small changes.
A continuous measure that is less subjective and that can be relied on to show genuine decreases or increases in functional ability over time would be useful both for clinical research and for routine patient management.
In a separate study, researchers used Microsoft Kinect -- a motion-sensing input device designed mainly for home video gaming -- to perform a postural control assessment. The $200 device was found to be reliable in measuring the impairment of MS patients using short stance tests, said Sebastian Mertens, a medical student at the NeuroCure Clinical Research Center-Charité in Berlin, Germany.
Mertens and his colleagues performed a cross-sectional study comparing 100 patients with MS with 60 healthy controls. The speed of three types of movements -- pitch, roll, and 3D -- was measured and compared with the Expanded Disability Status Scale (EDSS), a timed 25-foot walk (T25W), a short maximum speed walk test (SMSW), and the WALK-12 evaluation. Participants did an open stance, a closed stance, and a tandem stance (i.e., with one foot in front of the other).
Participants in the study performed the test once with closed eyes and once with open eyes. ICC values for the three movements were 0.927, 0.900, and 0.943, respectively, with eyes closed, and 0.968, 0.933, and 0.971, respectively, with eyes open. In the closed stance, the 3D speed correlated modestly with the other measures:
- EDSS: 0.458 (P<0.001, eyes open) and 0.531 (P<0.001, eyes closed)
- SMSW: -0.332 (P<0.001) and no correlation with closed eyes
- T25W: 0.318 (P<0.01, eyes open) and 0.331 (P<0.001, eyes closed)
- WALK12: 0.340 (P<0.001, eyes open) and 0.478 (P<0.001, eyes closed)
There were no significant correlations with a patient's age, height, or body mass index. In the closed stance, MS patients were also found to have higher compensatory arm movements with eyes closed (P=0.001) and open (P=0.013) than in the control group.
"Kinect-based postural control assessment is fast and feasible," the researchers concluded.