October 2003

Speeding Ahead

By Janice Fisher, MS, PT, ATP

Tower wheelchairs are becoming a familiar sight at the malls, in restaurants, and at our own hospital, the Hospital For Sick Children in Washington, DC. And it is not just adults you see in power wheelchairs; more children are powering around the school halls and neighborhoods. This is because specialists are realizing the importance of the relationship between mobility and the cognitive development of a child, so children are being put in power chairs earlier in life. With the ability to move around, children are able to explore their own environments. They are more apt to develop language, link concepts in their minds, understand cause and effect, and, in general, improve their independence, confidence, and quality of life.

Power mobility works on a continuum just as walking does. A child does not go from being unable to drive a power wheelchair to zipping through the halls of her school and weaving around people and doorways in one trial. It is our role as therapists to keep children safe while letting them explore and do what they want. If the child is a walker, you put a gate across the stairway and childproof the room, and if the child is a power wheelchair driver, you slow down the speed and widen the space by removing obstacles.

In power mobility training, we start simply by using one directional switch for “start” and “stop.” When a child fully understands the concept and can safely start and stop for obstacles, we progress by adding more directions (ie, right, left, and backward), adding obstacles, increasing the speed, and changing other variables to make power mobility more challenging.

GETTING STARTED IN THE CLINIC

Once appropriate seating and positioning for a child are determined, access, switches, and switch placement are the other clinical decisions made in the art of power mobility.

The first piece of the problem is determining the most appropriate body part to be used for access.

Fortunately in today’s clinic, a voluntary body-part motion can easily be converted into a voltage signal to operate a motor through advanced sensor technology. There are many possible body-part responses that can be used—from an eye blink to a head, hand, finger, or foot movement. It is also important to determine a body part that will not grow tired with use.

Next, we choose a switch control that matches the child’s needs most effectively. For instance, the common jelly bean switch comes in bright colors and clicks when it is activated. This switch works well with a child who is visually oriented and knows her colors, as well as a child who is oriented to the auditory clicking of the switch. Of course, the child needs the strength to press the switch, as well as the coordination and motor control to release the switch when necessary. A Microlyte switch is appropriate for a child who has weak muscles and decreased range of motion because it can be activated with a minimal amount of energy expenditure. This is often a good switch to use with diagnoses such as spinal muscular atrophy and osteogenesis imperfecta. We have even used Microlyte switches with some premature infants to operate toys. A proximity switch is also a good switch to use for weak muscles with decreased range of motion, as well as for children who have a difficult time releasing a switch. There are switches with textures for kids with sensory needs. As you walk through the floors of product technology conferences, you can see a myriad of innovative specialty switches that just might solve your clinical puzzle.

Finally, after you have identified your most reliable body part and your optimal switch match, you need to fine-tune the body/switch relationship with the best placement of the switch. The switch placement can be angled in three-dimensional orientation to match the child’s anatomical alignment and functional movement. We usually start with a piece of Orthoplast with Velcro and bend it in a perfect orientation for the child to operate the switch. We sometimes also work toward an off-the-shelf mount with the power wheelchair order.

At the Hospital For Sick Children, we use an electronic platform for power mobility evaluation, access/switch clinical decision-making, and power mobility training. A child is rolled onto the platform in a manual wheelchair, and we attach the desired electronic control to the wheelchair or lap tray. The child then uses the switch to move the entire platform package around the halls. Since it is so simple to set up and use, this platform allows us to conduct a trial with children who do not necessarily demonstrate much potential. We sometimes use it as a large “cause and effect” toy for children, rewarding them with vestibular effects. Most often, we are pleasantly surprised when the child shows more potential than we originally thought.

Although the electronic platform is fairly large and difficult for a child to maneuver in tight spaces, its benefits outnumber the difficulties. First, and most important, many of the seating and positioning issues are eliminated during an evaluation session. In the past, we used to borrow a power wheelchair from an equipment company for a power mobility trial. This chair usually was not perfect for the size of the patient and did not have the necessary seating options for optimal seating and positioning. We would spend a large portion of the session positioning and sizing the child to the wheelchair with towel rolls and foam pieces.

Now, with the platform, the child usually arrives at an appointment in a manual wheelchair that has been customized, so we can delve right into the power mobility piece of the puzzle. Second, access setups are easy to swap. In our system, we have an electronic controller with many drives. We use each drive for a different access method. We simply change the controller to a different drive and then we change the access method. Third, storage space is simplified. We do not need a fleet of power wheelchairs to satisfy our children with their many sizes and needs; we do not have enough space in our facility to store these chairs, and it would be very expensive. The platform is large, but it can be stored in one corner of the gym.

When we have figured out most access solutions for a child, we call our equipment representative and try out the particular power base, seating system, and controls we have considered, and confirm our ideas.

CASE STUDY: PROGRESSION, ASSESSMENT, AND TRAINING

Mohamed is a young boy with athetoid cerebral palsy. He is intelligent and motivated. He has a lot of difficulty with motor control issues secondary to the nature of his diagnosis. We began his first power mobility trial when he was about 6 years old. At the time, we had only a joystick attachment. Although thrilled about mobilizing himself in a power device, Mohamed was very frustrated by the difficulty of operating a joystick. A joystick contains a great deal of power, as the speed and direction are all controlled in one stick. One slight movement in a different direction could change the direction or speed of the chair in an undesirable manner.

The more Mohamed tried to gain control, the more his efforts distorted his tone and made him drive erratically. We dealt with his control issues by using external devices. Because of the nature of Mohamed’s tonal patterns, he tends to exhibit overflow in his muscles when he attempts to move. For this reason, we had a neoprene strap on his right driving hand pulling his arm into more flexion at his elbow. In this position, he had more control because he was unable to shoot out into full extension and get stuck in a nonfunctional position. We had another neoprene strap that he could tuck his left hand into and pull because this arm also exerted energy with his driving efforts. Finally, we made a tennis ball addition to the joystick so that it would be a larger target and allow Mohamed to access the joystick no matter what configuration his hand was in at the time.

In second and third trials, we arrived at more options for our power wheelchairs, and we were able to give Mohamed more possibilities. We added the ability to use four distinct switches for the directions—forward, right, left, and backward. Mohamed performed more consistently with this method, using four jelly bean switches as his directional switches and accessing the switches on his lap tray with both hands. When he was slightly off with his targeting, he could still get a pure direction if he activated the switch. He also became rigid in his desires to have the same color switch represent the same direction every time he practiced, such as, for example, “green” for “go” or “forward.”

Although they were better than the joystick, the four switches accessed by the hands were not the easiest and most functional access method. We borrowed a head array from an equipment manufacturer, and in one trial, Mohamed drove a power device with ease. However, this was not a total solution to the problem, as Mohamed’s mother really wanted him to use his hands more and was not won over by the idea of the head array.

In the final trial, we designed a compromise: We decided to try both the head and the hands. We designed a U-shaped Orthoplast mount and put it on the inside of Mohamed’s headrest. To this we Velcroed two spec switches on the left and right sides of the headrest mount for right and left turns. The remaining switches were mounted on a slanted angle of Orthoplast that extended across the width of Mohamed’s laptray: the “forward” switch on the far right side of the lap tray and the “backward” switch on the left.

Mohamed was very successful with this setup, and his mother was pleased. He began to blend his directions so that he would depress his forward switch with his hand and his right switch with his head to get just the right degree of turning. After many sessions of fine-tuning the switch placements and training, we placed an order for Mohamed’s first power wheelchair with exactly the same setup. When the chair finally arrived, we trained Mohamed on its use and his mother on the setup, breakdown, maintenance, and trouble-shooting issues. Mohamed was ready to take on the world.

MOVING ON

A final aspect of power wheelchair training that is vital to a successful outcome is using fun training strategies. A child is enthralled the first time she moves herself in a power wheelchair, but as with anything else, the toy loses its appeal after it is played with over time. The activity of negotiating a power wheelchair as a means in itself works for a time, but then the child needs to use it as a means for getting somewhere. We have performed a number of activities using the power wheelchair as it is intended—a mobility device—in scavenger hunts, obstacle courses, hide-and-seek, and follow the leader, and for simply going on outings. It is our role as therapists to keep power mobility fresh and fun. We are working with children, and we need to keep things fun by incorporating mobility activities that are enjoyable and age-appropriate for our new power wheelchair user. We also need to provide the stepping-stone for the next level of power mobility, the transition of our client to home, school, and community.

Janice Fisher, MS, PT, ATP, is a clinical specialist for the Hospital For Sick Children, Washington, DC.