FDA approves shoulder implant for quadriplegics
Device helps restore hand function
The simplest activities of daily living are out of reach for most quadriplegics. However, the dream of independence may become a reality for some patients, thanks to a new implantable device recently approved by the U.S. Food and Drug Administration (FDA) in Rockville, MD.
Researchers have been investigating the possibilities of electrical stimulation restoring function to quadriplegics for more than a decade, and their research has culminated in the development of the Freehand System by Neuro-Control in Cleveland.
The Freehand System uses electrical stimulation to replace the brain’s nerve impulses in patients who have quadriplegia due to spinal cord injury. Small shoulder movements trigger the device, giving patients up to two hand grasps: cupping the hand to pick up larger objects, and pressing the thumb against the forefingers for activities such as writing and brushing teeth. However, patients must have some movement in the upper body for the system to work. (See box, at right, for additional patient selection criteria.)
"It’s not for just any spinal cord injury," says Franki Cassaday, OTR, occupational therapy supervisor at Craig Hospital in Englewood, CO. "The patient needs to have good shoulder strength and appropriate muscles that respond to stimulation. There are also non-physical factors, such as a good support system." An occupational therapist and hand surgeon should evaluate patients to determine whether they are good candidates for the system, she adds.
The patient’s input also is an important part of the implantation decision. "In the evaluation, the OT and surgeon may find that one arm is a better choice for the implant, but the patient may feel strongly about using the other arm," Cassaday says. "For instance, the left arm may look like a better candidate clinically, but the patient may be very right-handed."
The system consists of an external shoulder position sensor, which translates small shoulder movements into a control signal. (See drawing of the system, p. 196.) The external controller, usually located on the wheelchair, receives the control signal and processes the information into radio waves to power and control the implant. A transmitting coil is worn over the implanted stimulator. A pacemaker-sized stimulator is implanted in the chest and sends electrical stimuli through wires to eight electrodes attached to the paralyzed hand and forearm muscles. This stimulation causes the muscles to contract, providing the patient with a functional hand grasp. Additional reconstructive hand surgery may or may not be performed, depending on the patient’s needs.
One to two months of preliminary therapy is necessary to prepare the muscles. In addition, most patients in the clinical studies received five months of rehabilitation and training following implantation of the system, according to FDA spokeswoman Sharon Snider.
In the field study of 61 quadriplegics, 20% required additional surgery for reasons related to the implantation of the device. These included:
• need to reposition the device;
• need to replace broken electrodes;
• need to remove electrodes because of infection;
• need to repair damage to the skin at the site of the incision.
Reported side effects included swelling and discomfort in 21% of the patients, skin irritation in 23%, and irritation from incisions or sutures in 16%.
Shriner’s Hospital for Children in Philadelphia and Brigham and Women’s Hospital in Boston both have implanted the Freehand System in patients. Other hospitals are exercising more caution. Cindy Hartley, OTR, BS, spinal cord injury clinical supervisor at the Shepherd Center in Atlanta, says the Freehand System is promising, but the hospital wants to investigate further.
Hartley attended a seminar given by the manufacturer about the Freehand System and brought that information back to her facility, a nationally recognized spinal center. One thing Shepherd still wants clarified is the total cost of the system to the patient. "One reason we’re holding off is we’re not sure how much of this will actually be covered by health plans," she says.
Cassaday says NeuroControl estimates the cost for the entire process at about $60,000 to $70,000, including rehabilitation, consulting, and surgery. However, there are also long-term costs. Just like any other medical device, the Freehand System requires maintenance. For example, batteries and external cables probably need replacement once every one or two years at a cost of roughly $300 annually, but the implant itself should not need replacement, according to NeuroControl.
Before Cassaday and her colleagues at Craig Hospital make a final decision about the system, she says they must look closely at patients who have been using the system and see if it has decreased their overall costs. Although the initial outlay is high, there may be long-term savings due to reduced need for attendant care and home modifications. In addition, in some instances the restored function may allow patients to return to work. "The system can definitely enhance the life of some people," Cassaday says. "It helps them be more independent."
NeuroControl has licensing and patenting rights to the device, which is based on technology known as neural prosthetics and functional neuromuscular stimulation.
[For more information, call (800) 471-9387. Or visit NeuroControl’s World Wide Web home page at www.neurocontrol.com.]
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