Measurement of balance in a natural environment.
- A validity, reliability and feasibilty study.-

Balance impairments, which are common in persons with CVA, Parkinson's disease,
cerebellar ataxia, or vestibular disorders, and in elderly people, are a major
problem because it reduces the person's mobility and self-efficacy. The
importance of measuring balance is fourfold: 1) to get a good diagnosis, 2) to
evaluate therapy, 3) to evaluate the progress of a disease, and 4) as a
therapeutic tool. Current instruments to asses balance, i.e. clinical tests and
laboratory equipment, have their limitations by being subjective and imprecise,
or complex and expensive and restricted to a laboratory environment. Insole
pressure devices and accelerometers are two new promising techniques to measure
balance objectively and in a person's natural environment. Although current
studies emphasize the potential of these techniques to measure balance, their
validity and reliability to measure balance of patients with neurological and
vestibular disorders has not been evaluated.

To assess the validity, reliability and feasibility of accelerometers and the
Pedar Mobile system for measuring balance during standing and walking of
patients with neurological and vestibular disorders.

It is a validity study. Ten patients with CVA, 10 with Parkinson's disease, 10
with cerebellar ataxia, 10 with a vestibular disorder, and 10 helathy controls
are selected to participate. Balance is measured by accelerometry and an insole
pressure device. The feasibility to perform these measurements is evaluated by
questionnaires. All measurements are performed at the same day.

To measure balance with accelerometers, two sensors (1 x 1 x 1 cm) are placed
on the thorax of the subject which are connected with wires to a data recorder
(15 x 9 x 3,5 cm; 500 gram) which is worn on a belt around the waist.
To measure balance with the Pedar Mobile system, the subject wears a data
recorder (4,5 x 10,5 x 17,5 cm; 750 gram) which is worn in a custom made vest,
and insoles (2mm thick) are placed inside the shoes of the subject.
Questionnaires are used to assess the feasibility of the balance instruments.

The balance measurements are not painfull or dangerous. One or two
researchers/therapists will stand/walk beside the patient during the balance
measurements to minimize the risk of falling. Patients with severe balance
problems do not perform the measurements with eyes closed. The measurements
have a low physical strain.