As therapists and providers, we have all had some
very challenging and difficult clients throughout our
careers. Some of our clients’ seating needs are so
intricate that trying to provide them with adequate stability
can take significant time and equipment. Since these clients’
seating needs are so complex, it is very easy to lose sight of
the fact that we may be able to provide independent
mobility to these individuals through the use of alternative
When a very complex child or adult comes to us for an
evaluation, the goal is to always provide them with the best
opportunity for independence. In order to provide the best
service we can, we need to think of every option available
that may improve the client’s level of independence.
The Possibilities of a Single Switch
A few years ago, I met a little boy who was 3 years old
when I was part of an assistive technology team that was
evaluating him for an augmentative communication device.
We found him to be very intelligent and to have a strong
desire to communicate and participate in activities as independently
as possible. Upon evaluation, we found that his
active controlled movements were significantly impacted by
his cerebral palsy. However, we did find he was able to utilize
his right hip flexion consistently with a switch mounted
over his right knee to control the scanning feature of a communication
During the trial period for a communication device, we
found he was very creative and adapted quickly to the
device. At this time, we had a discussion with him and his
family about the possibility of using this type of switch
control to move from his manual chair to a power chair for
greater independence. His family said they had no idea it
was a possibility for him to drive a power chair with his
impaired manual dexterity. I told his family as long as he
had a good access point to control a switch, then greater
independence was a strong possibility. We moved forward
with the process.
The power mobility evaluation was a long process requiring
multiple evaluation appointments. We evaluated him for
a seating system on the first appointment and then we evaluated
for different alternative controls and his driving skills
during the following appointments. Although we knew that
single switch would probably be the best access method for
driving, we wanted to be sure that all other alternative controls
that might provide more direct control of the power
wheelchair were ruled out first. We found his best control
for driving a power wheelchair was consistent with what we
had found for communication.
We decided to start him off with a four-way scanning
configuration. He had rapid success with this configuration,
so we moved forward to an eight-way scanning configuration.
He picked up driving with single-switch scanning very
quickly. He has been driving now for more than two years
with single-switch scanning and has had the opportunity to
try other access methods as he develops further control
over his lower extremities. He continues to find that driving
with an eight-way scanning system for control of his power
wheelchair is the most successful for him.
Requirements for Single-Switch Driving
Single-switch scanning evaluations can be very daunting
and time consuming, but the reward is incredible when we
can deliver the highest level of independence to our client.
It’s helpful to understand the skills a client needs to drive
with single-switch scanning.
- The client must have the vision to see the display. The
devices available provide two options, either bright LED
lights that move through a rotation of scanning sequences,
or a brightly colored arrow on a power wheelchair display.
Either option requires that the display that has the arrow or
lights must be located in a spot easily seen by the user, but
out of their visual field enough that it does not interfere with
their vision for driving the power wheelchair.
- The client must have the ability to attend to the scanning
screen. The client must be able to watch the screen
provided in all environments and visually track the scanning
light or arrow of the device until it reaches the direction
they want to move.
- The client must have at least one consistent movement.
This allows one-switch access to occur.
- The client must be able to hit the switch at the appropriate
time in order to choose the direction they want the
power wheelchair to move. This requires timing that is not
easily achieved by all clients. If their timing is off, then
switch driving can be a very frustrating process. However,
don’t rule out this type of driving too quickly. Give your
client a chance to learn how to use the device. This at times
can take many days of a trial period or, sometimes, even
months to develop the ability to drive a power wheelchair.
- They must be able to hold the switch down for as
long as they desire the power wheelchair to move in the
chosen direction. They must also be able to release the
switch in a safe amount of time, should they get into a
- Consider what would benefit your client most, fourway
or eight-way single-switch scanning. Four-way scanning
offers four directions of movement for the user: forward,
left, mode, reverse and right. Eight-way scanning
offers more choices of direction: forward, veer forward/left,
left turn, veer reverse left, mode, reverse, veer reverse
right, right turn, and veer forward/right. Some clients find
eight-way scanning more efficient once they can increase
the speed at which the scanner moves around the scanning
Some programming options can accelerate the learning
process. Turn the scan rate to a slow speed to decrease
frustration. Then, as the client seems to get the hang of driving,
turn the scan speed up to allow access to the different directions at a faster speed. Be sure to adjust the driving
parameters such as turning speed, acceleration, deceleration
and other driving parameters to ensure the wheelchair
drives at an appropriate speed for your client. Try different
switches to ensure you have the best switch match for the
individual. Utilize light-touch switches if holding down the
switch is difficult, or utilize a switch with a heavier spring in
it for the client who is tough on their equipment.
Remember, a switch can truly be mounted anywhere. We need to remain creative with options when looking at
mounting any switch. The mounting location will probably
be as unique as the individual we are working with.
We always need to remember, we owe our clients the
greatest level of independence they can achieve. If it is an
access method that seems labor intensive to us, we still
need to allow the client to determine if it is too labor
intensive for them or if the independence that the access
method provides outweighs the time factor for them. Given
the chance, they may just surprise you with the level of
independence they can achieve.