Cutaneous anaesthesia of the lower leg can improve sensibility in the diabetic foot. A double-blind, randomized clinical trial

Diabetes-induced Neuropathic Mechanical Hyperalgesia Depends on P2X4 Receptor Activation in Dorsal Root Ganglia

Peripheral diabetic neuropathy (PDN) manifests in 50-60% of type I and II diabetic patients and is the major cause of limb amputation. Adequate therapy for PDN is a current challenge. There are evidences that the activation of the P2X4 receptor (P2X4R) expressed on microglial cells of the central nervous system takes part in the development of neuropathic pain. However, there is an open question: Is P2X4R activation on dorsal root ganglia (DRG) involved in the development of neuropathic pain? To answer this question, this study verified the involvement of P2X4R expressed in DRG cells on diabetes-induced neuropathic mechanical hyperalgesia in rats. We found that intrathecal or ganglionar (L5-DRG) administration of a novel P2X4R antagonist (PSB-15417) or intrathecal administration of oligodeoxynucleotides (ODN)-antisense against the P2X4R reversed diabetes-induced neuropathic mechanical hyperalgesia. The DRG of the diabetic neuropathic rats showed an increase in P2X4R expression, and the DRG immunofluorescence suggested that P2X4R is expressed mainly in satellite glial cells (SGC). Finally, our study showed a functional expression of P2X4R in SGCs of the rat's DRG, because the P2X4R agonist BzATP elicits an increase in intracellular calcium concentration in SGCs, which was reduced by PSB-15417. These findings indicate that P2X4R activation in DRG is essential to diabetes-induced neuropathic mechanical hyperalgesia. Therefore, this purinergic receptor in DRG could be an interesting therapeutic target for quaternary P2X4R antagonists that do not cross the hematoencephalic barrier, for the control of neuropathic pain, preserving central nervous system functions.

Herbal medicine foot bath for the treatment of diabetic peripheral neuropathy: protocol for a randomized, double-blind and controlled trial

Background

As a common complication of diabetes, the incidence of diabetic peripheral neuropathy (DPN) is 60–70% worldwide. DPN is a major risk factor for diabetic foot, which may lead to foot ulceration and even amputation. The treatment of DPN remains challenging. Our preliminary study demonstrated that the external application of Tangbi Waixi (TW) decoction to the lower extremities relieved clinical symptoms and improved nerve conduction velocity in DPN patients. The aim of this study was to verify the efficacy of TW among DPN patients and evaluate the herb mixture’s safety using rigorous methodological designs.

Methods/design

This study is a multicenter, double-blind, randomized controlled trial. A total of 640 DPN patients will be recruited and randomized to receive a foot bath with either the TW decoction or control drug. Participants will be assessed at baseline and 12 and 24 weeks after treatment. The primary outcome was the change of the Toronto Clinical Scoring System (TCSS). Secondary outcomes were nerve conduction velocity, blood glucose, blood lipids, serum inflammatory cytokines, and the European Quality of Life Five-Dimension Scale (EQ-5D) and TCM symptom scores.

Discussion

This multicenter, prospective, randomized clinical trial will provide valuable data regarding the efficacy and safety of foot bath treatment with TW decoction. Positive results would provide a novel treatment regimen for DPN patients.

Trial registration

Chinese Clinical Trial Registry, ChiCTR-IOR-16009331. Registered on 8 October 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2856-4) contains supplementary material, which is available to authorized users.

Cutaneous sensitivity in unilateral trans-tibial amputees

Aim

To examine tactile sensitivity in the leg and foot sole of below-knee amputees (diabetic n = 3, traumatic n = 1), and healthy control subjects (n = 4), and examine the association between sensation and balance.

Method

Vibration perception threshold (VPT; 3, 40, 250Hz) and monofilaments (MF) were used to examine vibration and light touch sensitivity on the intact limb, residual limb, and homologous locations on controls. A functional reach test was performed to assess functional balance.

Results

Tactile sensitivity was lower for diabetic amputee subjects compared to age matched controls for both VPT and MF; which was expected due to presence of diabetic peripheral neuropathy. In contrast, the traumatic amputee participant showed increased sensitivity for VPT at 40Hz and 250Hz vibration in both the intact and residual limbs compared to controls. Amputees with lower tactile sensitivity had shorter reach distances compared to those with higher sensitivity.

Conclusion

Changes in tactile sensitivity in the residual limb of trans-tibial amputees may have implications for the interaction between the amputee and the prosthetic device. The decreased skin sensitivity observed in the residual limb of subjects with diabetes is of concern as changes in skin sensitivity may be important in 1) identification/prevention of excessive pressure and 2) for functional stability. Interestingly, we saw increased residual limb skin sensitivity in the individual with the traumatic amputation. Although not measured directly in the present study, this increase in tactile sensitivity may be related to cortical reorganisation, which is known to occur following amputation, and would support similar findings observed in upper limb amputees.

Systematic review of treatments for diabetic peripheral neuropathy

AIM

To evaluate treatment options for neuropathic pain and sensory symptoms resulting from diabetic peripheral neuropathy of the feet.

METHODS

The databases PubMed, Embase and Web-of-Science were searched for randomized controlled trials, published in the period from database inception to 2 July 2015, that evaluated treatments for diabetic peripheral neuropathy of the feet with placebo or standard treatment as comparators. Participants in these trials included people with diabetes mellitus and diabetic peripheral neuropathy who were given any treatment for diabetic peripheral neuropathy. Risk of bias was assessed using the Delphi list of criteria. Data from the trials were extracted using standardized data extraction sheets by two authors independently. All analyses were performed using RevMan 5.2. In case of clinical homogeneity, statistical pooling was performed using a random effects model.

RESULTS

This review included 27 trials on pharmacological, non-pharmacological and alternative treatments. In the meta-analysis of trials of α-lipoic acid versus placebo, total symptom score was reduced by -2.45 (95% CI -4.52; -0.39) with 600 mg i.v. α-lipoic acid (three trials), and was reduced by -1.95 (95% CI -2.89; -1.01) with 600 mg oral α-lipoic acid (two trials). Significant improvements in diabetic peripheral neuropathy symptoms were found with opioids, botulinum toxin A, mexidol, reflexology and Thai foot massage, but not with micronutrients, neurotrophic peptide ORG 2677 and photon stimulation therapy.

CONCLUSION

In this review, we found that α-lipoic acid, opioids, botulinum toxin A, mexidol, reflexology and Thai foot massage had significant beneficial results.

Retrospective Study on the Analgesic Activity of a Topical (TT-CTAC) Cream in Patients With Diabetic Neuropathy and Other Chronic Pain Conditions

Treatment of chronic pain in diabetic neuropathy or neuropathic pain of other origins is challenging. Compounded topical formulations have evolved as potential treatment options. The objective of this retrospective study was to evaluate the efficacy of a compounded topical cream (Transdermal Therapeutics). Two versions of TT-CTAC cream were evaluated: cream 6B and cream 7B. Both creams contain ketamine (10%), baclofen (2%), gabapentin (6%), amitriptyline (4%), bupivacaine (2%), and clonidine (0.2%). Additionally, one cream (7B) contains nifedipine (2%). The primary efficacy outcome was the change in numeric pain intensity score from pretreatment to posttreatment. Secondary outcomes were qualitative grading (excellent, good, poor, or no effect), reduction in oral medication, and avoiding referral to a pain specialist. Information on 283 patients was evaluated, 205 received the 7B and 78 received 6B creams. The pain score decreased by 2.4 ± 2.4 (35%) with the 6B cream (from 7.8 ± 1.6 to 5.4 ± 2.0, P < 0.001) and by 3.0 ± 2.4 (40%) with the 7B cream (from 7.5 ± 1.7 to 4.5 ± 2.2, P < 0.001). Excellent or good effects were reported in 82% of the patients in the 6B and in 70% in the 7B groups. Reduction in oral pain medication was seen in 35% of the patients in the 7B and in 20% in the 6B groups. In the opinion of the treating physicians, the cream therapy caused the avoidance of a pain specialist referral in 53% of the patients in the 6B and in 39% in the 7B groups. The creams were equally effective in diabetic neuropathy, neuropathic pain, or other chronic pain states. We conclude that both creams provided excellent pain relief in the majority of the patients studied and may be a useful modality for pain therapy.

Improvement of hand sensibility resulting from application of anaesthetic cream on the forearm: importance of dose and time

Introduction

A local anaesthetic cream, EMLA®, applied temporarily to the forearm can improve sensory functions in the hands, both in healthy individuals and in patients with nerve injury. The treatment concept is an example of guided plasticity where the dynamic capacity of the central nervous system is used for therapeutic purposes. However, the optimal dose and duration of the anaesthetic cream is not known and this is addressed here.

Methods

Sixty healthy volunteers participated in this experimental study. They were randomised to one of six groups of 10 and received either 10 g or 20 g of EMLA® on the volar part of the forearm for either 60, 90 or 120 min, respectively. Outcome measures were touch thresholds and discriminative touch in digits II and V.

Results

There was a statistically significant improvement in touch threshold as well as discriminative touch in all six groups. However, there were no statistically significant differences between the six different dose and duration combinations.

Conclusions

It is concluded that 10 g of EMLA® applied to the volar part of the forearm for 60 min may be adequate to induce improved hand sensibility.

Vibrotactile perception in finger pulps and in the sole of the foot in healthy subjects among children or adolescents

Aims

To evaluate vibrotactile perception at different frequencies in fingers and in foot in healthy girls and boys.

Methods

Vibration perception thresholds (VPTs) were measured in 283 healthy (8–20 years), consecutively included, girls (n=146) and boys (n=137); i.e., 269 children after excluding those with diseases or disorders possibly affecting the nervous system. Thresholds were measured in finger pulps of index and little fingers (seven frequencies; 8–500 Hz) and at first and fifth metatarsal head and at heel in the sole of the foot (six frequencies; 8–250 Hz;) using Multi Frequency Tactilometry.

Results

VPTs, divided in six groups by age and gender (i.e., 8–10 years, 11–15 years and 16–20 years), at all three sites in the sole increased with higher frequencies, but without gender differences. Thresholds at 64 and 125 Hz were generally higher at heel compared to metatarsal heads. VPTs in finger pulps of index and little fingers, with no finger differences, had a different pattern with increasing thresholds with frequency, but with lower thresholds at 64 and 125 Hz. Thresholds at lower frequencies were higher in finger pulps, while at higher frequencies VPTs were lower in finger pulps than in the sole of the foot; thus, vibration perception in the sole was better than perception in finger pulps at lower frequencies and opposite at higher frequencies. VPTs were higher among adolescents than in younger children in the foot, while thresholds were lower in the finger pulps among adolescents, particularly in index finger. Thresholds in finger pulps of index and little fingers, particularly at higher frequencies, correlated with each other, which the three sites in the sole also did.

Conclusions

VPTs in fingers and in feet are different as related to frequency in healthy girls and boys. Multi Frequency Tactilometry is a future valuable method to detect neuropathy in children and adolescents.

Vibration thresholds are increased at low frequencies in the sole of the foot in diabetes-a novel multi-frequency approach

AIMS

To evaluate multi-frequency tactilometry as a method to measure vibrotactile sense in the sole of the foot in subjects with diabetes.

METHODS

Vibration thresholds were investigated at five frequencies (8, 16, 32, 64 and 125 Hz) at three sites (first and fifth metatarsal heads and heel) in the sole of the foot in subjects with Type 1 and Type 2 diabetes (n = 37). Thresholds were compared with healthy, age- and gender-matched subjects (n = 37) and related to glycaemic levels, subjective estimation of sensation in the feet and to perception of touch.

RESULTS

Vibration thresholds were significantly higher in subjects with diabetes compared with healthy subjects at low frequencies (8, 16 and 32 Hz) at all measured sites, and also at 64 Hz for the metatarsal heads. Perception of touch and subjective estimation of sensation were significantly impaired in subjects with diabetes. Glycaemic levels, which were higher in subjects with diabetes, did not correlate with vibration thresholds at 32 Hz (most sensitive to Meissner's corpuscles) or with touch thresholds in subjects with diabetes. Vibration thresholds at 32 Hz correlated significantly with perception of touch (rho = 0.45-0.65; P < 0.01) and with subjective sensation (rho = -0.38 to -0.52; P < 0.001) in subjects with diabetes. Perception of touch and subjective estimation of sensation did also correlate (rho = -0.51 to -0.80; P < 0.002).

CONCLUSIONS

Tactilometry is effective in detecting neuropathy in the sole of the foot at low frequencies of mainly 8-32 Hz, indicating that at least Meissner's corpuscles, or their related large nerve fibres, are affected by diabetes.

Principles of brain plasticity in improving sensorimotor function of the knee and leg in patients with anterior cruciate ligament injury: a double-blind randomized exploratory trial

Background

Severe traumatic knee injury, including injury to the anterior cruciate ligament (ACL), leads to impaired sensorimotor function. Although improvements are achieved by training, impairment often persists. Because good sensorimotor function is associated with better patient-reported function and a potential lower risk of future joint problems, more effective treatment is warranted. Temporary cutaneous anesthesia of adjacent body parts was successfully used on the hand and foot to improve sensorimotor function. The aim of this study was to test whether this principle of brain plasticity could be used on the knee. The hypothesis was that temporary anesthesia of the skin area above and below the knee would improve sensorimotor function of the ipsilateral knee and leg in subjects with ACL injury.

Methods

In this double-blind exploratory study, 39 subjects with ACL injury (mean age 24 years, SD 5.2, 49% women, mean 52 weeks after injury or reconstruction) and self-reported functional limitations and lack of trust in the knee were randomized to temporary local cutaneous application of anesthetic (EMLA®) (n = 20) or placebo cream (n = 19). Fifty grams of EMLA®, or placebo, was applied on the leg 10 cm above and 10 cm below the center of patella, leaving the area around the knee without cream. Measures of sensory function (perception of touch, vibration sense, knee kinesthesia) and motor function (knee muscle strength, hop test) were assessed before and after 90 minutes of treatment with EMLA® or placebo. The paired t-test was used for comparisons within groups and analysis of variance between groups, except for ordinal data where the Wilcoxon signed rank test, or Mann–Whitney test, was used. The number of subjects needed was determined by an a priori sample size calculation.

Results

No statistically significant or clinically relevant differences were seen over time (before vs. after) in the measures of sensory or motor functions in the EMLA® group or in the placebo group. There were no differences between the groups due to treatment effect (EMLA® vs. placebo).

Conclusions

Temporary cutaneous anesthesia of adjacent body parts had no effect in improving sensorimotor function of the knee and leg in subjects with severe traumatic knee ligament injury.