ABSTRACT
BACKGROUND AND OBJECTIVES:
Sensory function may be altered in chronic low back pain (CLBP), which may alter the perception of therapeutic currents. The aim of this study was to verify whether the risk of poor prognosis for CLBP pain influences the amplitude elicited at the sensory threshold (ST) in different modalities of neuromuscular electrical stimulation (NMES).
METHODS:
This is a quasi-experimental counterbalanced study with 40 subjects divided into four groups (n=10 each), according to the risk of poor prognosis for pain: no risk (control group - CG), low (LrG), medium (MrG), and high (HrG) risks. Four modalities of NMES were tested: two medium frequency currents (Aussie current [AC] and Russian current [RC]) and two low frequency currents (commonly known as functional electrical stimulation [FES]), with two phase durations of200 μs (FES_200) and 500 μs (FES_500), in the region of the lumbar multifidus muscles. All subjects were exposed to all current modalities with interval periods, and when the ST was reached, the amplitude of the current measured in mA was recorded.
RESULTS:
The currents that elicited the highest and lowest amplitude in the ST were FES_200 and AC, respectively. As for the risk of poor prognosis, the highest amplitudes were for the HrG and the lowest for the LrG.
CONCLUSION:
The amplitude of the current elicited in the ST tended to be higher among those with a higher risk of poor prognosis for pain and, among the currents, those of medium frequency elicited lower amplitudes.
Keywords:
Electrical stimulation therapy; Low back pain; Psychosocial impact
HIGHLIGHTS
Psychosocial factors seem to influence the sensory threshold in chronic low back pain
High risk of poor prognosis for pain elicits a higher amplitude in the sensory threshold
The aussie current generates lower amplitude at the sensory threshold compared to other currents
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CG = control group; LrG = low risk group; MrG = medium risk group; HrG = high risk group; AC = Aussie current; RC = Russian current; FES = functional electrical stimulation with two phase durations 200 μs (FES_200) and 500 μs (FES_500); ES = effect size; mean difference between means (≠ mean). Asterisks indicate statistically significant differences (p<0.05).
CG = control group; LrG = low risk group; MrG = medium risk group; HrG = high risk group; AC = Aussie current; RC = Russian current; FES = functional electrical stimulation with two phase durations 200 μs (FES_200) and 500 μs (FES_500); ES = effect size; mean difference between means (≠ mean).Asterisks indicate statistically significant differences (p<0.05).