Clinically Speaking

Open CRT & ALS: From Snowflakes to Ice Cubes

• By Steve Mitchell
• Oct 01, 2016

Open Complex Rehab involves sharing practice-based evidence to improve the effectiveness of complex rehab technology (CRT) for specific populations using an open, user-centered, collaborative approach.

In this final installment on amyotrophic lateral sclerosis (ALS), I will show how this approach can lead to better CRT outcomes for users who require the most complex power chair configurations.

Let me start by sharing practice-based evidence from my own clinical setting, since we at the Cleveland VA Medical Center started our multidisciplinary ALS clinic in 2008:

• The vast majority of veterans with ALS have been successful using conventional joysticks. Almost every veteran who initially drove with a joystick has continued to use a joystick for as long as he/she had the power chair.
• During this period, only seven proximity head arrays were prescribed. All but one were prescribed for veterans with Flail Arm syndrome. Only one veteran who was initially using a standard joystick needed to use a head array later on.
• Only two recipients of proximity head arrays used them proficiently without significant customization.
• No ALS power chairs have been equipped with proportional joysticks configured for chin or foot control.
• The success rate for low-effort and mini joysticks has been limited.
• No ALS power chairs have been equipped with true sip-’n’-puff driving systems.

At first glance, one might conclude that my “success rate” with alternative controls is lower than most other settings. If my definition for success was strictly mobility, that would be true. Many people seem to use that criteria, which I think is unfortunate. I have heard many “success stories” where someone who could no longer use a joystick uses an alternative control to drive across the clinic. If it turned out they never tilted their seating system beyond 30° because they can’t overcome gravity, is this really success?

Redefining Successful Mobility

We can and should do better. At a minimum, a successful ALS outcome should be defined in terms of the user’s ability to safely drive and effectively use the seating system. With ALS, both are equally important.

This type of outcome can be difficult to achieve if we are counting on the function in a single body part to control everything on the chair.

Hybrid Alternative Driving Systems (HADS) combine characteristics of more than one system to enable key functions to be assigned to other points of control. HADS can be effective when an end user lacks sufficient head control, oral motor function, active movement, or cognitive function to use any single type of system.

Because ALS is such a pervasive disease that affects motor neurons throughout the body, the concept behind HADS makes total sense. So why are we only now reading about them in the October 2016 issue of Mobility Management?

It’s not the technology that’s holding us back, it’s how we have traditionally approached the configuration of a complex rehab power chair. Using the conventional approach, creating a hybrid system for one user would be a labor-intensive process that would involve mounting four or five switches in accessible locations, determining the function of each switch, and routing its cable to the location associated with that function. In essence, each HADS becomes a one-of-a-kind system that would be difficult to modify because everything is wired in place.

On the other hand, if the basic configuration provides a flexible infrastructure that supports switch access, it becomes possible to implement HADS in a more practical way. Instead of configuring the chair like a “snowflake” where no two are alike, an ALS power chair becomes an “ice cube” that can adapt to changing needs.

AltDrive Armrest Conversion Module

Approximately 20 percent of the ALS power chairs I prescribe are potential candidates for hybrid systems. Some will have marginal joystick drivers who may not use a joystick for long, while other drivers will have Flail Arm syndrome. The AltDrive Armrest Conversion Module is a self-contained unit that replaces the original joystick and the entire armrest assembly with an Omni display and a compact joystick.

It was created so I could easily determine whether joystick driving was feasible for marginal users and allows a HADS to be used on the chair as a second driving system.

AltDrive Ready Connector Hub

What can seven pre-routed extension cables do to the versatility of an ALS power chair? Much more than you might think. I developed the “Connector Hub” to eliminate the need to hard wire switch cables to specific locations in order to be able to perform specific functions. To assign a function to a switch, simply plug it in to a color-coded extension cable located on one of the seat rails or accessory rail. Each of these cables has been routed to a central “hub” on the backrest. Two more cables are routed from the hub to the display and are plugged into the power and mode jacks. The result is a “plug & play” network that works like a switchboard (no pun intended). Assigning a function to a switch is simply a matter of identifying the same colored plug at the hub and choosing the desired function.

To complete the infrastructure, let’s throw in a two-function pneumatic switch (shown mounted to the Si-X module in the picture). When combined with an AltSwitch seating interface and a switch driving interface, it becomes possible for any switch to function as a power switch, mode switch, operate a seating function, or be used as part of a hybrid alternative driving system.

Raising One Bar By Lowering Another

Complex rehab is an area where we may find that if we “lower the bar” required to implement the technology, we can raise the bar with respect to the outcomes we can expect.

For example, I provided all three of the HADS configurations pictured here — sip-’n-’puff knee steering, head steering and toggle-drive knee steering systems — to actual veterans. Would it be surprising to know that each uses a nearly identical programming profile?

It’s true. All three systems are configured as four-axis step-latched systems. Four-axis step-latched driving requires five switch inputs (a separate mode switch is required).

It is an ideal configuration for many users with ALS because it requires only brief inputs to drive, and the reverse command can be used to slow down. The incremental nature of a stepped-latch configuration is also easier to learn because the user can see the results of each input. Three-axis stepped-latch configurations eliminate the need for a mode switch, but require the user to stop instead of slowing down and toggle between forward/reverse.

Two of the three configurations in the picture use a two-function pneumatic switch. Unlike a dedicated sip-’n’-puff driving system, the two-function variety does not require precise regulation of intraoral pressure.

In practice, it has been underutilized due to a misperception that good oral motor or respiratory function are required. Provided that sustained inputs aren’t required, most users with ALS can use this type of switch! Because it provides two inputs from a single location that is not affected significantly when the seating system is used, we should be considering it more than we should be ruling it out.

Used in combination with the modular headrest “position & place” switch mounts from last month’s issue, the bar to implementing HADS has never been lower!

Replicating Ideas & Changing the Status Quo

Once a manufacturer understands the functionality of what you are trying to do, they can implement the concept even more effectively.

Such is the case with the prototype connector hub from Quantum Rehab shown here on their Q6 Edge 2.0 “ALS concept chair”.

That’s also a prototype “position & place” fiber optic sip-’n’-puff head array based on a Stealth Products I-Drive system.

Maybe Open CRT does give us hope for changing the status quo!

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