To investigate the normal data of pain-related evoked potentials (PREP) elicited with a concentric surface electrode among normal, healthy adults and the relationship between PREP and pain intensity.
Sixty healthy volunteers (22 men and 38 women; aged 36.4±10.7 years; height, 165.4±7.8 cm) were enrolled. Routine nerve conduction study (NCS) was done to measure PREP following electrical stimulation of hands (C7 dermatome) and feet (L5 dermatome). Negative peak (N), positive peak (P) latencies, peak to peak (NP) amplitudes, conduction velocity (CV), and verbal rating scale (VRS) score were obtained. Linear regression analysis tested for significant relevance between variables of PREP and VRS score.
Normal NCS results were obtained in all subjects. N latency of hand PREP was 163.8 ±40.0 ms (right) and 161.0±39.9 ms (left). N latency of foot PREP was 178.0±43.9 ms (right), 180.4±43.4 ms (left). NP amplitude of hands was 20.6±10.6 µV (right) and 21.9±11.6 µV (left). NP amplitude of feet was 18.8±8.3 µV (right) and 19.0±8.4 µV (left). The calculated CV was 13.2±4.7 m/s and VRS score was 3.8±1.0. A highly significant positive correlation was evident between VRS score and NP amplitude (y=0.1069x+1.781, r=0.877, n=60, p<0.0001).
PREP among normal, healthy adults revealed a statistically significant correlation between PREP amplitude and VRS score.
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To evaluate the effects of functional electrical stimulation (FES) to ankle dorsiflexor (DF) and ankle plantarflexor (PF) on kinematic and kinetic parameters of hemiplegic gait.
Fourteen post-stroke hemiplegic patients were considered in this study. Electrical stimulation was delivered to ankle DF during the swing phase and ankle PF during the stance phase via single foot switch. Kinematic and kinetic data were collected using a computerized motion analysis system with force plate. Data of no stimulation (NS), DF stimulation only (DS), DF and PF stimulation (DPS) group were compared among each other.
Peak ankle dorsiflexion angle during swing phase is significantly greater in DS group (-1.55°±9.10°) and DPS group (-2.23°±9.64°), compared with NS group (-6.71°±11.73°) (p<0.05), although there was no statistically significant difference between DS and DPS groups. Ankle plantarflexion angle at toe-off did not show significant differences among NS, DS, and DPS groups. Peak knee flexion in DPS group (34.12°±13.77°) during swing phase was significantly greater than that of NS group (30.78°±13.64°), or DS group (32.83°±13.07°) (p<0.05).
In addition to the usual FES application stimulating ankle DF during the swing phase, stimulation of ankle PF during stance phase can help to increase peak knee flexion during the swing phase. This study shows the advantages of stimulating the ankle DF and PF using single foot switch for post-stroke gait.
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To evaluate the effect of semiconditional electrical stimulation of the pudendal nerve afferents for the neurogenic detrusor overactivity in patients with spinal cord injury. Forty patients (36 males, 4 males) with spinal cord injury who had urinary incontinence and frequency, as well as felt bladder contraction with bladder filling sense or autonomic dysreflexic symptom participated in this study.
Patients with neurogenic detrusor overactivity were subdivided into complete injury and incomplete injury groups by ASIA classification and subdivided into tetraplegia and paraplegia groups by neurologic level of injury. Bladder function, such as bladder volumes infused to the bladder until the first occurrence of neurogenic detrusor overactivity (Vini) and the last contraction suppressed by electrical stimulation (Vmax) was measured by water cystometry (CMG) and compared with the results of each subgroup.
Among the 40 subjects, 35 patients showed neurogenic detrusor overactivity in the CMG study. Among these 35 patients, detrusor overactivity was suppressed effectively by pudendal nerve afferent electrical stimulation in 32 patients. The infusion volume until the occurrence of the first reflex contraction (Vini) was 99.4±80.3 ml. The volume of saline infused to the bladder until the last contraction suppressed by semiconditional pudendal nerve stimulation (Vmax) was 274.3±93.2 ml, which was significantly greater than Vini. In patients with good response to the pudendal nerve afferent stimulation, the bladder volume significantly increased by stimulation in all the patients.
In this study, semiconditional electrical stimulation on the dorsal penile afferent nerve could effectively inhibit neurogenic detrusor overactivity and increase bladder volume in patients with spinal cord injury.
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