Four clinical trials have been performed investigating whether early initiation of NMES could minimize shoulder subluxation, a problem in 20-40% of stroke survivors (see Volume II, Chapter 36 on stroke rehabilitation). (Faghri et al., 1994; Chantraine et al., 1999; Linn et al., 1999; Wang et al., 2000). The impairments of subluxation and shoulder pain can be minimized in the majority of patients while improving passive joint range and volitional deltoid activation after 4-6 weeks of training. This training is insufficient to yield meaningful reduction if the NMES is delayed for 6-12 months post-subluxation (Wang et al., 2000). It should be noted that these studies used reduction of subluxation as an outcome and not upper limb functional activities.
The value of NMES to the training of upper limb function remains controversial. Recent studies have begun to test the contribution of NMES particularly to hand function (Cauraugh et al., 2000; Alon et al., 2002; Cauraugh and Kim, 2002, 2003a, b, c; Alon and Ring, 2003; Alon et al., 2003; Popovic et al., 2003). Outcome measures used in hand function evaluation vary considerably. Cauraugh and colleagues only use the box and blocks test while others also use the Jebsen-Taylor and the nine-hole peg (Alon and Ring, 2003; Alon et al., 2003; Kimberley et al., 2004). Popovic et al. (2003) recently used a comprehensive test battery that included many ADLs that depend on the upper limb collectively termed upper extremity functioning test (UEFT) as well as hand drawing test and patients testimonial statements regarding reduced upper extremity motor activity long (MAL) tests.
Diversity of training programs and the delay of training initiation have contributed to the reluctance of the clinical community to accept FES as a valuable intervention. Most studies that tested true upper limb function and not just impairments enrolled only patients with chronic stroke. Four clinical investigations synchronized clearly described task-specific activities with stimulation. Such synchronization resulted in upper limb functional improvement in 70-80% of participants (Alon and Ring, 2003; Alon et al., 2003; Berner et al., 2004; Ring et al., 2005). The authors added a cautionary note
Table 9.1. Development stages of FES systems for use in spinal cord injury.
Type of system
FDA regulatory approval
Cardiovascular exercise Breathing assist V
Yes (Regys, Ergys)
Yes (Avery Mark IV) (IDE: Atrotech) Completed Yes (Freehand and Handmaster)
V No Completed Yes (Parastep)
V Yes (Vocare)
V Yes that while the gains of hand functions were both statistically and clinically meaningful, the vast majority of patients improve the time of performance but did not re-learn functional ability.
Gait performance has been enhanced by FES during ambulation (Malezic et al., 1987). The most common target muscle for stimulation has been the dorsiflexors of hemiparetic patients. The stimulation is typically synchronized with the gait cycle, so that the dorsiflexors are active during the swing phase. The main outcome measures that improve after 4-5 months of use are walking speed (20-27%) and physiological cost index (PCI). Walking speed after the training period without the stimulator only improves 10-14% if the stimulation was limited to the dorsiflexors, however (Burridge et al., 1997b; Taylor et al., 1999; Yan et al., 2005), multisegment stimulation of both plantar flexors and dorsiflexors has been used in stroke. Training involved increasing speed of ambulation as well as stair climbing and walking on different terrains. Using this paradigm, gait velocity improved 36% and cadence by 19% (Alon and Ring, 2003), which represents an improvement from the results with dorsiflexors stimulation alone.
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