Durable Medical Equipment Section - Functional Neuromuscular Stimulation to Provide Ambulation

IMPORTANT REMINDER

This Medical Policy has been developed through consideration of medical necessity, generally accepted standards of medical practice, and review of medical literature and government approval status.

Benefit determinations should be based in all cases on the applicable contract language. To the extent there are any conflicts between these guidelines and the contract language, the contract language will control.

The purpose of medical policy is to provide a guide to coverage. Medical Policy is not intended to dictate to providers how to practice medicine. Providers are expected to exercise their medical judgment in providing the most appropriate care.

Description

Functional neuromuscular stimulation attempts to replace stimuli from destroyed nerve pathways with sequential electrical stimulation of muscles to enable spinal-cord injured patients to stand or walk independently, or to maintain healthy muscle tone and strength. In general, only patients with lesions from T4 to T12 are candidates. Lesions at T1-T3 are associated with poor trunk stability, while lumbar lesions imply lower extremity nerve damage. Technologies differ in how the electrodes are placed, either implanted, placed transcutaneously, or percutaneously. To date, only one device has been approved by the U.S. Food and Drug Administration (FDA), the Parastep®® Ambulation System. Using percutaneous stimulation, the Parastep® device delivers trains of electrical pulses to trigger action potentials at selected nerves at the quadriceps (for knee extension), the common peroneal nerve (for hip flexion), and the paraspinals and gluteals (for trunk stability). In addition, patients use a walker or elbow support crutches for further support. The electrical impulses are controlled by a computer microchip attached to the patient's belt that synchronizes and distributes the signals. Moreover, there is a finger-controlled switch that permits patient activation of the stepping.

Other devices include a reciprocating gait orthosis (RGO) with electrical stimulation. The orthosis used is a rather cumbersome hip-knee-ankle-foot device linked together with a cable at the hip joint. The use of the RGO may be limited by the difficulties involved in putting the device on and taking it off.

Functional neuromuscular stimulation is also used for gait training in post-stroke patients unable to restore normal gait with conventional physical therapy.

Policy/Criteria

Functional neuromuscular stimulation to provide ambulation, including ambulation in patients with spinal cord injury and post-stroke patients, is considered investigational.

Scientific Background

The clinical impact of the Parastep® device rests on identification of clinically important outcomes. The primary outcome of the Parastep® device and the main purpose of its design is to provide a degree of ambulation that improves the patient’s ability to complete the activities of daily living, seek employment, or positively benefit the patient’s quality of life. Physiologic outcomes (e.g., conditioning, oxygen uptake.) have also been reported, but these are intermediate short-term outcomes, and it is not known whether similar or improved results could be attained with other training methods. In addition, the results are reported for mean peak values, which may or may not be a consistent result over time. The effect of the Parastep® on physical self-concept and depression are secondary outcomes and similar to the physiologic outcomes; interpretation is limited due to lack of comparison with other forms of training.

The largest study was conducted by Chaplin and colleagues who reported on ambulation outcomes using the Parastep® I in 91 patients. (2) Of these 91 patients, 84 (92%) were able to take steps and 31 (34%) were able to eventually ambulate without assistance from another person. Duration of use was not reported. Other studies on the Parastep® device include a series of five studies from the same group of investigators, which focused on different outcomes in the same group of 13–15 patients. (3-7) In a 1997 study, Guest and colleagues reported on the ambulation performance of 13 men and 3 women with thoracic motor complete spinal injury. (7) All patients underwent 32 training sessions prior to measuring ambulation. The group mean peak distance walked was 334 meters, but there was wide variability, as evidenced by a standard deviation of 402 meters. The mean peak duration of walking was 56 minutes, again with wide variability, evidenced by a standard deviation of 46 minutes. It should be noted that peak measures reflect the best outcome over the period evaluated; peak measures may be an inconsistent one-time occurrence for the individual patient. The participants also underwent anthropomorphic measurements of various anatomic locations. Increases in thigh and calf girth, thigh cross-sectional area, and calculated lean tissue were all statistically significant. The authors emphasized that the device is not intended to be an alternative to a wheelchair, and thus other factors such as improved physical and mental well being should be considered when deciding whether or not to use the system. The same limitations were noted in a review article by Graupe and Kohn, who stated that the goal for ambulation is for the patients to get out of the wheelchair at will, stretch, and take a few steps every day. (8)

Jacobs and colleagues reported on physiologic responses related to use of the Parastep® device. (4) There was a 25% increase in time to fatigue and a 15% increase in peak values of oxygen uptake, consistent with an exercise training effect. There were no significant effects on arm strength. Needham-Shropshire and colleagues reported no relationship between use of the Parastep® device and bone mineral density, although the time interval between measurements (12 weeks), and the precision of the testing device, may have limited the ability to detect a difference. (5) Nash and colleagues reported that use of the Parastep® device was associated with an increase in arterial inflow volume to the common femoral artery, perhaps related to the overall conditioning response to the Parastep®. (6) Also, Guest and colleagues reported significant improvements in physical self-concept and decreases in depression scores. (7) Finally, it should be noted that evaluations of the Parastep® device were performed immediately following initial training or during limited study period durations. (2, 9-11) There are no data regarding whether patients remain compliant and committed with long-term use.

Additional published studies addressing functional neuromuscular stimulation for ambulation include the following:

• Brissot and colleagues reported independent ambulation was achieved in 13 of 15 patients, with 2 patients withdrawing from the study. (9) In the home setting, 5 of the 13 patients continued using the device for physical fitness, but none used it for ambulation.
• Sykes and colleagues found low use of a reciprocating gait orthosis device (RGOs) with or without stimulation over an 18-month period. (10)
• The more recent Davis study of a surgically implanted neuroprosthesis for standing and transfers after spinal cord injury showed mixed usability/preference scale results for ambulation with device assistance versus conventional transfers in 12 patients followed for a 12-month period post-discharge. (11) Therefore, the advantage of using device assistance could not be evaluated.
• Johnston and colleagues reported that seven subjects, ages 7-20 years, who received an eight-channel implanted lower extremity functional electrical stimulation (FES) system for standing and walking, completed four activities faster and five activities more independently with FES as compared to lower limb braces alone. (12)

A 2008 Cochrane review was conducted to assess the effects of locomotor training on improvement in walking for people with traumatic spinal cord injury. (15) Four randomized, controlled trials involving 222 patients comparing locomotor training with no treatment found no between-group difference and concluded that data are insufficient and more research is needed. A second meta-analysis assessed the effects of functional electrical stimulation (FES)-assisted gait for people with of SCI. (16) The authors included 36 papers and concluded that evidence was insufficient because of small sample size, many reported benefits were not carefully investigated and different methodologies were used.

Post-Stroke

Daly and colleagues compared gait component execution in 32 post-stroke patients randomized to gait training with or without FNS. (13) Gait component execution was measured by the Tinetti 12-point scale for assessing gait component coordination.  The authors found gait training with FNS with intramuscular electrodes significantly improved gait component execution and knee flexion coordination over gait training without FNS.  However, improvements in balance, overall limb coordination and the 6-minute walking test were not statistically significant.  Additionally, final health outcomes such as the ability to perform activities of daily living or quality of life were not evaluated in this study.

In 2006, a Cochrane review was conducted to determine if electrostimulation improved functional motor ability and the ability to perform activities of daily living following stroke. (14)  Twenty-four randomized controlled trials comparing electrostimulation to no treatment or to physical therapy alone met inclusion criteria.  Results were mixed and the authors noted limitations in the trials including variations between studies in time after stroke, functional levels and dose of electrostimulation, and the possibility of selection and detection bias in the majority of the trials reviewed, and the majority of analyses only contained one trial.  The authors concluded that data is insufficient and more research is needed to address question related to the type and dose of electrostimulation and the time for treatment following stroke.

Summary

In summary, the Parastep® system is not designed to be an alternative to a wheel chair and offers, at best, limited, short-term ambulation. Final health outcomes, such as ability to perform activities of daily living or quality of life have not been reported. An updated search of the MEDLINE database through September 4, 2008 identified no new published data that alter these conclusions.

References

1. BlueCross BlueShield Association Medical Policy Reference Manual, Policy No. 8.03.01
2. Chaplin E. Functional neuromuscular stimulation for mobility in people with spinal cord injuries. The Parastep® I System. J Spinal Cord Med 1996;19(2):99-105
3. Klose KJ, Jacobs PL, Broton JG et al. Evaluation of a training program for persons with SCI paraplegia using the Parastep®®1 Ambulation System: Part 1. Ambulation performance and anthropometric measures. Arch Phys Med Rehabil 1997;78:789-93
4. Jacobs PL, Nash MS, Klose J et al. Evaluation of a training program for persons with SCI paraplegia using the Parastep®®1 Ambulation System: Part 2. Effects on physiologic responses to peak arm ergonometry. Arch Phys Med Rehabil 1997;78:794-98
5. Needham-Shropshire BM, Broton JG, Klose J et al. Evaluation of a training program for persons with SCI paraplegia using the Parastep®®1 Ambulation System: Part 3. Arch Phys Med Rehabil 1997;78:799-803
6. Nash MS, Jacobs PL, Montalvo BM. Evaluation of a training program for persons with SCI paraplegia using the Parastep®®1 Ambulation System: Part 5. Arch Phys Med Rehabil 1997;78:808-14
7. Guest RS, Klose J, Needham-Shropshire BM, Jacobs PL. Evaluation of a training program for persons with SCI paraplegia using the Parastep®®1 Ambulation System: Part 4. Arch Phys Med Rehabil 1997;78:904-907
8. Graupe D, Kohn KH. Functional neuromuscular stimulator for short-distance ambulation by vertain thoracic-level spinal-cord-injured paraplegics. Surg Neurol 1998;50:202-207
9. Brissot R, Gallien P, Le Bot MP et al. Clinical experience with functional electrical stimulation assisted gait with Parastep in spinal cord-injured patients. Spine 2000;25(4):501-8
10. Sykes L, Ross ER, Powell ES et al. Objective measurement of use of the reciprocating gait orthosis (RGO) and the electrically augmented RGO in adult patients with spinal cord lesions. Prosthet Orthot Int 1996;20(3):182-90
11. Davis JA Jr, Triolo RJ, Uhlir J et al. Preliminary performance of a surgically implanted neuroprosthesis for standing and transfers – where do we stand? J Rehabil Res Dev 2001;38(6):609-17
12. Johnston TE, Betz RR, Smith BT, Mulcahey MJ. Implanted functional electrical stimulation: an alternative for standing and walking in pediatric spinal cord injury. Spinal Cord. 2003;41(3):144-152
13. Daly JJ, Roenigk K, Holcomb J, et al. A randomized controlled trial of functional neuromuscular stimulation in chronic stroke subjects.  Stroke 2006;37(1):172-8. Epub 2005 Dec 1
14. Pomeroy VM, King L, Pollock A, et al. Electrostimulation for promoting recovery of movement or functional ability after stroke. Cochrane Database Syst Rev 2006;19(2):CD003241
15. Mehrholz J, Kugler J, Pohl M. Locomotor training for walking after spinal cord injury. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD006676
16. Nightingale EJ, Raymond J, Middleton JW, et al. Benefits of FES gait in a spinal cord injured population. Spinal Cord 2007;45(10):646-57. Epub 2007 Jul 24

Cross References

Electrical Stimulation Devices for Home Use, Regence Medical Policy Manual, DME, Policy No. 11

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