Clinically Speaking

ALS & Headrests: How Open CRT Offers New Opportunities

Last time, I reviewed some clinical aspects of amyotrophic lateral sclerosis (ALS) and their implications for power mobility. ALS power chairs are unique in that they must not only address a user’s needs at a given point in time; they must also address many foreseeable issues we can expect to encounter in the future. Their configuration should provide an infrastructure that allows them to be adapted to changing needs, and we need modular solutions to address those needs with less time, labor and technical expertise than is currently the case.

Oftentimes, our big-picture success depends on our execution of the individual details. If we use assessment, rather than assumption, to determine how effectively a product meets a given set of needs, we may find that relatively minor changes can make a big difference. Open Complex Rehab is about analyzing practice-based evidence, sharing what we find with others, and improving CRT through mutual collaboration.

Head Positioning Possibilities

If we measure an outcome in terms of an ALS power chair’s ability to meaningfully contribute to the user’s quality of life throughout the disease, we will find that the headrest plays an important role. Unfortunately, the industry’s approach to headrests and head arrays can limit what may be possible for an end user who has ALS.

If we want to encourage users to mitigate the adverse effects of gravity by tilting their seating systems, a comfortable headrest is essential. Still, we often sacrifice comfort when the headrest needs to achieve multiple clinical objectives.

We know that axial weakness will eventually progress to a point where the user will have difficulty holding his/her head erect against gravity. If this weakness is not symmetrical, there may be a tendency for the head to deviate laterally toward one side. With early detection, a simple lateral spot pad may remedy the problem. If allowed to continue unaddressed, it may become a significant problem that could become impossible to correct. The greater the progression, the greater the impact on the person’s quality of life. In most cases, we do not know if asymmetry will be a problem at the time we prescribe an ALS power chair.

Similarly, most users with ALS will not initially need switches on their headrests. However, a significant number may benefit later on as they lose anti-gravity movement.

When we prescribe conventional head arrays that have sensors embedded in a firm occipital pad, we are sacrificing a certain level of comfort to provide mobility.

ALS HeadrestsWith many of today’s products, the original hardware provided with the chair may need to be replaced in order to use positioning components or switches later on. A head array that can no longer be used for driving is often a poor substitute for a comfortable headrest, and its hardware may be significantly different. Too often, this need to replace rather than upgrade results in missed opportunities to have a positive effect on the long-term outcome.

We have tended to think of headrests that provide comfort, headrests that provide positioning, and head arrays as distinctly different products. In practice, I am finding that a significant number of users would benefit from characteristics of all three. Some would benefit from multiple characteristics simultaneously, while others require different characteristics at different stages of the disease.

Users with ALS would benefit from a modular headrest that is comfortable and provides enough positioning to address mild asymmetry. It should allow us to build on what’s already there and address emerging problems at the same time we identify them. It should be possible to convert it into a driving control, or convert it back to a headrest that provides switch access.

What’s Possible Now

ALS headrestWhile this may be a new way of conceptualizing the headrest, we do not have to wait for new products to be able to implement the concept. A 6"x4" occipital pad combined with two vertically oriented 4"x2" spot pads has roughly the same surface area as a 10" headrest, but provides significantly more lateral or suboccipital support. As importantly, it includes the infrastructure needed to address the more-challenging issues that may arise in the future.

For years I’ve been looking for better ways to mount switches on headrests. Current mounting hardware is either too rigid to accommodate minor variations in positioning or too flexible to provide efficient activation. Those who need these types of products need solutions that provide enough rigidity for efficient activation with a very limited amount of adjustability for precise placement. To appreciate how these characteristics have been effectively implemented in a mainstream product, one needs to look no further than the rearview mirror in a car.

Recently, I have been fabricating custom switch mounts using 1/4" stainless steel tubing, modular hose, a CNC ball socket adapter, and a flattened Loc-Line end cap. The assembly can be used in the standard Stealth ball, shaped by hand, and provides enough finetuning to position the switch for optimal efficiency.

ALS headrestAnother issue with today’s products is they provide very little support for the movements used to activate the switch. To understand the importance of this, let’s return to our analogy about cars. When we use the brake pedal, do we lift our foot off the floor and move our entire leg over, or do we keep our foot on the floor and rotate? Let’s refer to the former as “lifting and shifting.” One movement does the lifting to overcome gravity (hip flexion), while a second movement shifts everything laterally (hip adduction).

Very few people drive like this because it takes a considerable amount of effort. Human factors engineers design cars so the location of the pedals allows most drivers to use hip rotation while the heel stays on the floorboard for stability. Instead of “lifting and shifting,” most drivers are able to use “rotation with stabilization.” While we may take this for granted, a 1" to 2" difference in pedal placement is all that would be required for our daily commute in stop-and-go traffic to turn into a major workout.

When providing a conventionally configured head array to someone with ALS, don’t be surprised to find that “lifting and shifting” is the technique used to get to the lateral sensors and mode switch. While cervical rotation would be far more efficient, they primarily use forward and lateral flexion of their neck. Why? They may need to keep their head off the occipital sensor, and their only other source of stability rotation comes from surrounding neck muscles that are already working to stabilize the head. This problem is most obvious when they try to activate sensors or switches from a fully tilted position.

Combining an external source of support with the capability to precisely position switches and sensors within range is the key to implementing “rotation with stabilization” in a head-activated system. If this sounds very abstract and theoretical, one should look no further than the picture below to see this concept implemented in clinical practice.

ALS headrestSo, are the things I’ve discussed merely “technical details” of interest to a few motivated ATPs, or are they important clinical concepts that would make future products more effective? As I mentioned, sometimes our big-picture success depends on the execution of individual details.

In my final installment, I’ll demonstrate how all these details and concepts can be implemented in a way that can make a difference in ALS outcomes. The topic will be “Hybrid Alternative Driving Systems.” Never heard of them? Trust me, they’re very cool!

Editor’s Note: Steve Mitchell works at the Cleveland VA Medical Center. His opinions do not represent official policy or positions of the Department of Veterans Affairs.

This article originally appeared in the September 2016 issue of Mobility Management.

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