It is often said that technology drives innovation. If true, we should be in for an exciting ride in the field of rehabilitation over the next few decades. Miniaturized microelectronics, advanced robotics, sophisticated data processing systems, and new modalities of stimulating the peripheral and central nervous system are inspiring rehabilitation scientists and clinicians to probe novel methods for restoring function in individuals with neurological disorders. This chapter provides an overview of existing and emerging technologies that are beginning to cross over from the laboratory to the clinic. Their underlying assumptions are outlined, mechanisms of action discussed, and advantages and limitations highlighted. In some cases, FDA approval exists for these new technologies and their approved application is noted. While this chapter is not all-encompassing, since the field is moving so fast, this chapter focuses on those technologies that are most likely to enter the clinical domain of rehabilitation medicine in the near future.
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION
Transcutaneous electrical nerve stimulation (TENS) refers to the use of electrical current to stimulate peripheral nerves with skin surface electrodes, typically for the purpose of reducing chronic neuropathic pain, either due to peripheral or central injury. The physiological rationale for TENS-induced pain relief is thought to be dose-dependent inhibition of nociceptive nerve transmission. Various studies have used a wide range of intensity, pulse width, frequency, duration, and patterning, rendering generalizations about the efficacy of TENS clouded. A recent Cochrane Review concluded that the quality of evidence in sham-controlled studies to date has been low, and no strong recommendations can be made for nonpharmacologic treatments (including TENS) for neuropathic pain.1,2 Other uses of TENS include treatment of rotator cuff tendinopathy, but again, high-quality studies are lacking.3 While TENS is generally well tolerated, Table 94–1 lists common contraindications for electrical therapy in general.
Table 94–1Contraindications for Use of Electrical Therapy |Favorite Table|Download (.pdf) Table 94–1 Contraindications for Use of Electrical Therapy
|Stimulation over carotid sinus or over/across heart |
|Insensate or atrophic skin |
|Allergies to gels or pads |
|Inability to report stimulation of voice pain |
|Arterial or venous thrombosis, thrombophlebitis |
|Transcerebral, ocular, oral, or anterior neck electrode placement |
FUNCTIONAL ELECTRICAL STIMULATION
Similar to TENS, functional electrical stimulation (FES) uses pulses of electrical current to stimulate peripheral nerves. However, the term FES is usually restricted to electrical stimulation of peripheral nerves innervating the muscle(s) of interest, resulting in muscle contraction.4 FES systems have been used primarily in individuals with central nervous system injury for both functional or therapeutic purposes. Electrodes are commonly placed on the skin surface overlying the target nerve. More invasive means of directly implanting stimulating electrodes ...