A preliminary investigation into the effects of active interferential current therapy and placebo on pressure pain sensitivity: a random crossover placebo controlled study

Objective

(1) To determine the effect of active and placebo interferential current on muscle pain sensitivity using an experimental mechanically induced pain model. (2) To evaluate the predictive role of expectations, gender, baseline muscle pain sensitivity, and intervention order on placebo response.

Design

Randomized placebo controlled cross-over trial.

Setting

University research laboratory.

Participants

Forty healthy volunteers (20 females, 20 males).

Interventions

Active interferential current, placebo (sham) interferential current, and no treatment/control were applied to the lumbar area on different days.

Main outcomes measures

Pressure pain thresholds and placebo response.

Results

The two-way ANOVA with repeated measures analysis determined a significant interaction between condition and time (P = 0.002). Pairwise comparisons found differences between active interferential and the control condition at 15 minutes into treatment (mean difference = 0.890 kg/cm², 95% CI 0.023 to 1.757, P = 0.043) and at 30 minutes into treatment (mean difference = 0.910 kg/cm², 95% CI 0.078 to 1.742, P = 0.028). The increase in pressure pain thresholds between the active interferential and the control condition (1.12 kg/cm²) was clinically meaningful. Logistic regression analysis showed that the condition sequence order was the only variable that predicted placebo response (odds ratio 9.7; P = 0.028). If a subject started the sequence receiving placebo treatment first, the odds of responding to placebo would be approximately 10 times higher (i.e. 90% probability of being a placebo responder) than that of starting with an active treatment.

Conclusions

Active interferential was more efficient than control condition in decreasing muscle pain sensitivity. Placebo interferential was not significantly different from control. Treatment sequence demonstrated a strong association with placebo response. These findings have implications for future research characterizing and identifying placebo responders in physiotherapy.     

动态浊度法检测乳酸左氧氟沙星氯化钠注射液中的细菌内毒素

目的:应用动态浊度法定量测定乳酸左氧氟沙星氯化钠注射液中的细菌内毒素,并与凝胶法比较。方法:按《中国药典》2010年版二部收载的细菌内毒素检查方法及其指导原则进行干扰试验,确定样品最大稀释倍数。结果:当样品作8倍稀释时用动态浊度法的回收率值较高(100%左右),未见干扰作用;与凝胶法检测结果一致,均符合规定。结论:动态浊度法可以有效测定乳酸左氧氟沙星氯化钠注射液中的细菌内毒素含量。     

头孢米诺钠细菌内毒素检查法方法学研究

目的建立头孢米诺钠的细菌内毒素检查方法。方法参照中国药典2005年版附录中细菌内毒素检查法干扰试验要求进行试验,确定头孢米诺钠的细菌内毒素限值,用2个厂家的鲎试剂对3批头孢米诺钠进行干扰试验。结果头孢米诺钠经稀释至5m b.mL-1浓度时可有效地排除其对鲎试验的干扰作用。结论头孢米诺钠可用细菌内毒素检查法进行检测。     

注射用萘普生钠细菌内毒素检查法建立及方法学研究

目的建立注射用萘普生钠的细菌内毒素检查方法。方法参照中国药典2000年版附录中细菌内毒素检查法和细菌内毒素检查法应用指导原则要求进行试验,确定注射用萘普生钠的细菌内毒素限值,用不同厂家的鲎试剂对注射用萘普生钠进行干扰试验。结果注射用萘普生钠经稀释至0.5mg·mL-1浓度时可有效地排除其对鲎试验的干扰作用。结论注射用萘普生钠可用细菌内毒素检查法进行检测。     

Correlation between change in pain,disability, and surface electromyography topographic parameters after interferential current treatment in patients with chronic low back pain

[Purpose] Surface electromyography (SEMG) topography is used to objectively assess patients with low back pain (LBP). This study aimed to investigate the correlation between SEMG topographic variables, pain, and disability in patients with chronic LBP (CLBP) after interferential current (IFC) treatment, and to evaluate IFC treatment efficacy using SEMG topography. [Participants and Methods] Twenty nine patients with CLBP were recruited for a 6-week IFC treatment. Pain and disability scores, and the root-mean-square difference (RMSD) of SEMG topographic variables (relative areas [RAs] at flexion and extension) were compared before and after the intervention by repeated measures ANOVA; the correlation between variables was also explored and p-value was set at 0.001. [Results] Significant positive correlations between changes in pain score and the RMSD of RA at flexion (r(29)=0.593), and between changes in pain and disability scores (r(29)=0.426) were observed. All participants showed statistically significant improvements in the RMSD of RA at flexion, pain score, and disability score after IFC treatment. [Conclusion] SEMG topographic variables are closely associated with changes in pain score in patients with CLBP after IFC treatment. The RMSD of RA at flexion can be used as an objective marker in IFC treatment efficacy evaluation.     

Temporal interference stimulation targets deep brain regions by modulating neural oscillations

BackgroundTemporal interference (TI) stimulation of the brain generates amplitude-modulated electric fields oscillating in the kHz range with the goal of non-invasive targeted deep brain stimulation. Yet, the current intensities required in human (sensitivity) to modulate deep brain activity and if superficial brain region are spared (selectivity) at these intensities remains unclear.ObjectiveWe developed an experimentally constrained theory for TI sensitivity to kHz electric field given the attenuation by membrane low-pass filtering property, and for TI selectivity to deep structures given the distribution of modulated and unmodulated electric fields in brain.MethodsThe electric field threshold to modulate carbachol-induced gamma oscillations in rat hippocampal slices was determined for unmodulated 0.05–2 kHz sine waveforms, and 5 Hz amplitude-modulated waveforms with 0.1–2 kHz carrier frequencies. The neuronal effects are replicated with a computational network model to explore the underlying mechanisms, and then coupled to a validated current-flow model of the human head.ResultsAmplitude-modulated electric fields are stronger in deep brain regions, while unmodulated electric fields are maximal at the cortical regions. Both experiment and model confirmed the hypothesis that spatial selectivity of temporal interference stimulation depends on the phasic modulation of neural oscillations only in deep brain regions. Adaptation mechanism (e.g. GABA_b) enhanced sensitivity to amplitude modulated waveform in contrast to unmodulated kHz and produced selectivity in modulating gamma oscillation (i.e. Higher gamma modulation in amplitude modulated vs unmodulated kHz stimulation). Selection of carrier frequency strongly affected sensitivity to amplitude modulation stimulation. Amplitude modulated stimulation with 100 Hz carrier frequency required ∼5 V/m (corresponding to ∼13 mA at the scalp surface), whereas, 1 kHz carrier frequency ∼60 V/m (∼160 mA) and 2 kHz carrier frequency ∼80 V/m (∼220 mA) to significantly modulate gamma oscillation. Sensitivity is increased (scalp current required decreased) for theoretical neuronal membranes with faster time constants.ConclusionThe TI sensitivity (current required at the scalp) depends on the neuronal membrane time-constant (e.g. axons) approaching the kHz carrier frequency. TI selectivity is governed by network adaption (e.g. GABA_b) that is faster than the amplitude-modulation frequency. Thus, we show neuronal and network oscillations time-constants determine the scalp current required and the selectivity achievable with TI in humans.     

Does amplitude-modulated frequency have a role in the hypoalgesic response of interferential current on pressure pain sensitivity in healthy subjects? A randomised crossover study

Objective

To investigate the hypoalgesic effect of amplitude-modulated frequency during interferential current therapy using an experimentally induced mechanical pain model in normal subjects. This study examined pain pressure sensitivities achieved when the amplitude-modulated frequency parameter was present (100 Hz) and absent (0 Hz).

Design

Randomised controlled crossover trial with repeated measures.

Setting

University research laboratory.

Participants

Forty-six healthy volunteers (23 males, 23 females).

Interventions

Two interferential therapy protocols (with and without amplitude-modulated frequencies) were applied to the lumbar area on two different days.

Main outcome measures

Pressure pain thresholds over the lumbar area were measured before, during and after application of the interferential therapy protocols.

Results

A three-way analysis of variance with repeated measures failed to show any statistically significant difference between the two protocols in modifying pressure pain threshold values (mean difference 0.017 kg/cm², 95% confidence interval −0.384 to 0.350, P = 0.93). Statistically significant differences were identified (P < 0.001) between measurements, indicating a comparable decrease in pain sensitivity in both groups. However, the increase in pressure pain thresholds (0.76 kg/cm²) failed to reach a level of clinical importance.

Conclusions

The addition of an amplitude-modulated frequency parameter to interferential therapy did not influence mechanical pain sensitivity in healthy subjects. Amplitude-modulated frequency is therefore unlikely to have a physiological hypoalgesic effect.     

综合治疗腰椎间盘突出症疗效观察

目的：观察单纯牵引与综合治疗腰椎间突出症的临床疗效,探索一种确切的有效方法。方法：腰椎间盘突出症患110例,分为单纯牵引组50例,综合治疗组60例。单纯牵引组采用红外线自动热疗推拿牵引床行腰椎牵引治疗,每日1次,每次30min,10次为1疗程,连续2－3个疗程;综合治疗组采用立体动态干扰电疗仪和牵引疗法,每日1次,每次各30min,疗程同上,治疗后进行疗效评定。结果：单纯牵引组临床治愈9例,显效13例,有效19例,无效9例,总有效率82％;综合治疗组临床治愈17例,显效22例,有效19例,无效2例,总有效率96．7％。组间差异有显性（P＜0．05）。结论：综合治疗腰椎间盘突出症是一种行之有效的手段,建议推广应用。     

维D2果糖酸钙注射液细菌内毒素检查法的实验研究

目的建立维D2果糖酸钙注射液细菌内毒素检查法。方法按照《中华人民共和国药典》2005年版二部附录细菌内毒素检查法1和2005年版《中国药品检验标准操作规范》细菌内毒素检查法2,确定维D2果糖酸钙注射液细菌内毒素限值,用3个厂家鲎试剂对两个厂家5个批次的维D2果糖酸钙注射液进行干扰试验考察。结果维D2果糖酸钙注射液的浓度稀释到300倍时进行细菌内毒素检查无干扰作用。结论维D2果糖酸钙注射液采用细菌内毒素检查法检查是可行的。