Sitting pressure reduction induced by electrical stimulation during daily life in people with spinal cord injuries .

Pressures sores are mainly caused by pressure, shear forces, friction, or a
combination of these and usually occur over bony prominences such as the
ischial tuberosity. Wheelchair users with spinal cord injuries (SCI) sit for
long periods, resulting in long lasting high pressures of the tissue, which may
be even higher due to atrophy of the paralyzed muscles, leading to higher local
peak pressures. In addition, blood flow is reduced below the lesion due to a
loss of capillary network, failure of the skeletal muscle pump mechanism, drop
in blood pressure and occlusion of blood vessels.
Several methods have been developed to prevent pressure sores by improving the
sitting pressure distribution, e.g. special cushions and protective behavior
(e.g., lifting). Although the cushions can improve sitting pressure
distribution, they do not reduce muscle atrophy or improve blood flow.
Protective behavior has no unambiguous effect on the development of pressure
sores. Apparently, these methods may not be completely adequate, indicating a
need for additional methods.
A method to accomplish a better sitting pressure distribution, reduced muscle
atrophy, and increased blood flow is by activating the gluteal muscles using
electrical stimulation (ES), temporarily changing the buttock shape and
concomitantly the sitting pressure distribution. Until now, not much is known
about this method.

The main purpose of this study is to evaluate the effects of surface electrical
stimulation of the gluteal and hamstring muscles on sitting pressure under the
buttocks during daily life (3 hours). A second purpose is to compare the
effects of only gluteal muscle activation with a combined gluteal-hamstring
muscle stimulation.

Intervention study, no control group.

Activation of the paralyzed gluteal and hamstring muscles by electrical
stimulation.

The extra physical burden on the subjects is minimal. The paralyzed muscles
will contract but this will have hardly any effect on the subject. He/she will
be able to perform daily activities as usual. The time needed for this project
is limited to 14 hours for each subject, divided ovcer 2 sessions. There is a
small chance that the subjects find the stimulation painful. In that case, the
current will be decreased immediately. In about 10% of the population,
electrical stimulation may induce autonomic dysreflexia (high blood pressure).
This will be determined in a screening session. If this occurs, subjects will
be excluded from the experiments. The stimulation may induce some redness of
the skin, but this will disappear after a few hours.