High intensity-transcutaneous electrical nerve stimulation does not inhibit temporal summation of the nociceptive flexion reflex.

Pain facilitation contributes to chronic pain conditions. Transcutaneous electrical nerve stimulation (TENS) is used to alleviate pain. The effects of conventional TENS on chronic pain have been limited, and its effects on pain facilitation are controversial. Because the analgesic effects of TENS depend on the setting parameters (e.g., pulse intensities or treatment time), the optimal TENS settings to maximize analgesic effects under various pain conditions have been investigated. High-intensity TENS (HI-TENS), which involves tolerable-level pulse intensities for a short duration, is another conventional TENS method that used to alleviate pain. However, the effects of HI-TENS on pain facilitation remain unclear. The temporal summation of pain is widely used to evaluate pain facilitation, and the temporal summation-nociceptive flexion reflex (TS-NFR) is a neuropsychological parameter that can be used to evaluate pain facilitation. We aimed to investigate the effects of HI-TENS on the TS-NFR in healthy participants. Participants were randomly allocated into HI-TENS (n = 15) and control groups (n = 16). HI-TENS was administered at the left lateral lower leg for 1 min. The TS-NFR elicited by three noxious stimuluses at the left sural nerve was obtained from electromyography of the left biceps femoris. The nociceptive flexion reflex (NFR) was obtained by a single noxious stimulus. We measured the thresholds of the NFR and the TS-NFR at baseline and post-intervention. The application of HI-TENS significantly increased the NFR threshold (p = 0.013) but not the TS-NFR threshold (p > 0.05). These results suggest that HI-TENS does not inhibit pain facilitation.

Contralateral segmental transcutaneous electrical nerve stimulation inhibits nociceptive flexion reflex in healthy participants.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) is a non-invasive treatment to relieve pain. Contralateral TENS (i.e. TENS administered to the contralateral side of a painful body part) is beneficial when TENS cannot be directly applied to pain site, such as in cases of trauma. Although TENS produces segmental analgesia in an ipsilateral limb, it has been unclear whether TENS produces higher analgesic effects in the contralateral segmental area. The aim of the present study was to investigate the analgesic effects of TENS in contralateral segmental or extra-segmental areas on physiological and subjective pain outcomes, using a nociceptive flexion reflex (NFR) method. METHODS: We randomly allocated 60 healthy participants to three groups: contralateral segmental TENS (CS-TENS); contralateral extra-segmental TENS (CE-TENS); and contralateral placebo TENS (CP-TENS). CS-TENS was applied to right superficial sural nerve and CE-TENS was applied to the right superficial femoral nerve, each for 30 minutes. The magnitude of the NFR elicited by electrical stimulation of the left sural nerve was measured at baseline and at three subsequent 10-minute intervals. Subjective pain intensity was measured simultaneously with a visual analogue scale (VAS). RESULTS: At 30 min, the NFR magnitude of CS-TENS group was significantly lower than that of the CP-TENS group (p = 0.021). There were no significant differences in VAS scores among the groups at any time point. CONCLUSIONS: Our findings suggest that CS-TENS inhibited NFR. Although there was no significant between-group difference in subjective pain intensity, factors such as a placebo effect probably impacted it. SIGNIFICANCE: Our findings provide support for the contralateral approach at stimulation sites when TENS cannot be directly administered to a pain site (e.g. due to disease or trauma).

Comparison of the Effect of Sensory-Level and Conventional Motor-Level Neuromuscular Electrical Stimulations on Quadriceps Strength After Total Knee Arthroplasty: A Prospective Randomized Single-Blind Trial.

OBJECTIVE: To compare sensory-level neuromuscular electrical stimulation (NMES) and conventional motor-level NMES in patients after total knee arthroplasty. DESIGN: Prospective randomized single-blind trial. SETTING: Hospital total arthroplasty center: inpatients. PARTICIPANTS: Patients with osteoarthritis (N=66; mean age, 73.5±6.3y; 85% women) were randomized to receive either sensory-level NMES applied to the quadriceps (the sensory-level NMES group), motor-level NMES (the motor-level NMES group), or no stimulation (the control group) in addition to a standard rehabilitation program. INTERVENTIONS: Each type of NMES was applied in 45-minute sessions, 5d/wk, for 2 weeks. MAIN OUTCOME MEASURES: Data for the quadriceps maximum voluntary isometric contraction, the leg skeletal muscle mass determined using multiple-frequency bioelectrical impedance analysis, the timed Up and Go test, the 2-minute walk test, the visual analog scale, and the range of motion of the knee were measured preoperatively and at 2 and 4 weeks after total knee arthroplasty. RESULTS: The motor-level NMES (P=.001) and sensory-level NMES (P=.028) groups achieved better maximum voluntary isometric contraction results than did the control group. The motor-level NMES (P=.003) and sensory-level NMES (P=.046) groups achieved better 2-minute walk test results than did the control group. Some patients in the motor-level NMES group dropped out of the experiment because of discomfort. CONCLUSIONS: Motor-level NMES significantly improved muscle strength and functional performance more than did the standard program alone. Motor-level NMES was uncomfortable for some patients. Sensory-level NMES was comfortable and improved muscle strength and functional performance more than did the standard program alone.

Influence of the stimulus parameters of galvanic vestibular stimulation on unilateral spatial neglect.

Galvanic vestibular stimulation (GVS) stimulates the vestibular system electrically with low-amplitude direct current through surface electrodes applied to the left and right mastoids. The effects of GVS on unilateral spatial neglect (USN) in poststroke patients were recently reported, but the influence of the current intensity and application duration of GVS on USN has not been sufficiently investigated. Here we explored the influence of these stimulus parameters on USN. We recruited seven patients with right-hemisphere stroke and left-sided USN (four female) for this single-blind, sham-controlled cross-over trial. Their scores on the line cancellation test were measured under three stimulation conditions [left-cathodal/right-anodal GVS (L-GVS), right-cathodal/left-anodal GVS, and sham] at three time points (before the start of GVS, 10 min after the start of GVS, and 20 min after the start of GVS). The GVS intensity was set below the sensory threshold and differed among the patients (0.4-2.0 mA). The cancellation scores were significantly increased after 10 and 20 min L-GVS, with a greater increase observed after the latter (P<0.0001). The other stimulus conditions had no significant effect. There was a significant positive correlation between the change in the increase in the cancellation score with L-GVS and the total charge (r=0.81, P=0.0004). The effect of GVS on USN may depend on its application duration, current intensity, and polarity.

Galvanic vestibular stimulation may improve anterior bending posture in Parkinson's disease.

This study investigated the effects of binaural monopolar galvanic vestibular stimulation (GVS), which likely stimulates the bilateral vestibular system, on the anterior bending angle in patients with Parkinson's disease (PD) with anterior bending posture in a single-blind, randomized sham-controlled crossover trial. The seven PD patients completed two types of stimulation (binaural monopolar GVS and sham stimulation) applied in a random order 1 week apart. We measured each patient's anterior bending angles while he or she stood with eyes open and eyes closed before/after the stimulations. The anterior bending angles in both the eyes-open and the eyes-closed conditions were significantly reduced after the GVS. The amount of change in the eyes-closed condition post-GVS was significantly larger than that by sham stimulation. The amount of change in anterior bending angles in the GVS condition was not significantly correlated with Unified Parkinson's Disease Rating Scale motor score, disease duration, the duration of the postural deformities, and the anterior bending angles before the GVS. Binaural monopolar GVS might improve anterior bending posture in PD patients, irrespective of the duration and the severity of disease and postural deformities. Binaural monopolar GVS might be a novel treatment strategy to improve anterior bending posture in PD.

Effects of galvanic vestibular stimulation combined with physical therapy on pusher behavior in stroke patients: a case series.

BACKGROUND: A recent study investigated the effects of galvanic vestibular stimulation (GVS) on pusher behavior (PB) in post-stroke patients. However, there have been no reports about the effects of multisession GVS on PB. OBJECTIVE: The purpose of this study was to investigate the feasibility and effects of multisession GVS combined with physical therapy for PB in stroke patients. METHODS: Two stroke patients who showed PB were enrolled. The ABAB single-case design was used. Each phase lasted 1 wk. In phases A1 and A2, the patients underwent a 60-min-long physical therapy session 5 days a week. In phases B1 and B2, they underwent GVS for 20 min before each physical therapy session, and then the same physical therapy program as in phases A1 and A2 were performed. PB was evaluated using the Scale for Contraversive Pushing (SCP) and the Burke Lateropulsion Scale (BLS). Outcomes were tested at the baseline and after each phase. RESULTS: In both patients, the SCP scores were reduced only during phase B2. Although the BLS scores improved at the A1 phase, a larger improvement was seen at the two B phases. CONCLUSIONS: Multisession GVS combined with physical therapy may have positive effects on PB in clinical setting.

Effect of modulated-frequency and modulated-intensity transcutaneous electrical nerve stimulation after abdominal surgery: a randomized controlled trial.

PURPOSE: This study aimed to evaluate the effectiveness of transcutaneous electrical nerve stimulation (TENS) for treatment of postoperative pain and pulmonary functions (vital capacity [VC]; cough peak flow, [CPF]) in patients who underwent abdominal surgery. MATERIALS AND METHODS: Forty-eight patients were randomly allocated to receive TENS, placebo TENS, or no TENS (control) 1 hour a day for 3 days postoperatively. A 0-100 visual analog scale was used to assess pain at preintervention, mid-intervention, and postintervention on the third postoperative day. Pulmonary functions (VC, CPF) were evaluated by spirometer at preoperation (baseline) and at preintervention, mid-intervention, and postintervention on the third postoperative day. One-way analysis of variance was used to assess differences between groups at baseline. Mann-Whitney test was used to compare the control group with the placebo-TENS and TENS group, at each assessment timepoint. Two-way analysis of variance and Bonferroni post hoc test assessed the difference between the 2 (placebo-TENS×TENS) groups. A value of P<0.01 was considered statistically significant. RESULTS: The baselines were not significantly different between any groups. The TENS group had significant reductions in postoperative pain compared with the placebo group (P<0.01) and control group (P<0.01). There was also improvement in pulmonary functions (VC, CPF) at mid-TENS and post-TENS, but not in the placebo-TENS (P<0.01) or control groups (P<0.01). CONCLUSIONS: TENS is a valuable treatment to alleviate postoperative pain and improve pulmonary functions (ie, VC, CPF) in patients following abdominal surgery.

Feasibility study of a combined treatment of electromyography-triggered neuromuscular stimulation and mirror therapy in stroke patients: a randomized crossover trial.

BACKGROUND: Mirror therapy (MT) and electromyography-triggered neuromuscular stimulation (ETMS) are both effective treatments for impaired upper limbs following stroke. A combination of these two treatments (ETMS-MT) may result in greater gain than either treatment alone. OBJECTIVES: The feasibility and possible effects of ETMS-MT upon upper extremity function were investigated in stroke patients. METHODS: Thirteen post-acute stroke patients were randomly assigned to an immediate ETMS-MT group or a delayed ETMS-MT group and then underwent an 8-week training program. The immediate ETMS-MT group received ETMS-MT in addition to physical and occupational therapy (PT+OT) for 4 weeks. They then received only PT+OT for the next 4 weeks. In the delayed ETMS-MT group, interventions were provided in the reverse order. The main outcome measure was the Fugl-Meyer Assessment (FMA). RESULTS: The immediate ETMS-MT group showed significantly greater gain in FMA in the first 4 weeks. The delayed ETMS-MT group showed significantly greater gain in active range of motion during the latter 4 weeks. No adverse effects were reported following ETMS-MT. CONCLUSION: ETMS-MT might be as effective as independent MT or ETMS without causing any side effects. Future research should focus upon the direct comparisons between independent and combined interventions.

Effects of peripheral sensory nerve stimulation plus task-oriented training on upper extremity function in patients with subacute stroke: a pilot randomized crossover trial.

OBJECTIVE: To investigate the feasibility of peripheral sensory nerve stimulation combined with task-oriented training in patients with stroke during inpatient rehabilitation. DESIGN: A pilot randomized crossover trial. SETTING: Two rehabilitation hospitals. SUBJECTS: Twenty-two patients with subacute stroke. INTERVENTIONS: Participants were randomly assigned to two groups and underwent two weeks of training in addition to conventional inpatient rehabilitation. The immediate group underwent peripheral sensory nerve stimulation combined with task-oriented training in the first week, followed by another week with task-oriented training alone. The delayed group underwent the same training in reverse order. MAIN MEASURES: Outcome measures were the level of fatigue and Wolf Motor Function Test. Patients were assessed at baseline, one and two weeks. RESULTS: All participants completed the study with no adverse events. There was no significant difference in level of fatigue between each treatment. From baseline to one week, the immediate group showed larger improvements than the delayed groups in the Wolf Motor Function Test (decrease in mean time (± SD) from 41.9 ± 16.2 seconds to 30.6 ± 11.4 seconds versus from 46.8 ± 19.4 seconds to 42.9 ± 14.7 seconds, respectively) but the difference did not reach significance after Bonferroni correction (P = 0.041). Within-group comparison showed significant improvements in the Wolf Motor Function Test mean time after the peripheral sensory nerve stimulation combined with task-oriented training periods in each group (P < 0.01). CONCLUSION: Peripheral sensory nerve stimulation is feasible in clinical settings and may enhance the effects of task-oriented training in patients with subacute stroke.