Shashi Kumar C G
Manipal University, India
Scientific Tracks Abstracts: J Diabetes Metab
The prevalence of type 2 diabetes mellitus (T2DM) is rapidly rising worldwide. It has been associated with many micro-vascular and macro-vascular complications1. Among all the complications, peripheral neuropathy is considered to be the most common with prevalence 60 to 65% and 11% patients with diabetic neuropathy complaining of pain2, where 50% of all the inpatient admissions are due to foot complications caused by peripheral neuropathy (DPN)3,4 DPN is a result of injury to the Vasa nervorum, axons and atrophy of the axons leading to tissue damage5. All nerve fibres may be injured, but small myelinated and unmyelinated fibre�??s that transmit pain and temperature are most affected6. In association with injury to the nerves, reduced microcirculation of the blood is responsible for the development of ulcers, and infections of skin and bone in T2DM subjects with long duration of diabetes mellitus7. In many subjects with diabetic neuropathy, pain will develop as a symptom localized to the lower extremities, primarily the soles and toes8. Evidences suggest that long term complications of diabetes mellitus are associated with depressive symptoms, the neuropathic pain considered to be one of the major cause for the depression9,10. Current therapy for DPN is purely aiming to symptomatic relief of the pain through various drug administration. These drugs are effective, but often associated with central nervous system side effects and do not retard the advancement of the underlying neuropathy11. Other than pharmacological treatment, non-pharmacological management have also been suggested, including acupuncture12, infrared therapy13, and various electrotherapies, including transcutaneous electrical nerve stimulation (TENS) 14, and spinal cord electro stimulation 15. The efficacy of most conservative treatment options for painful DPN is still little known. Among the different alternatives for treatment, low-level laser therapy (LLLT) may hold the potential to induce a biostimulational effect on the nervous system16,17,18,19 The typical aetiology of DPN pain starts with injury to a peripheral nerve, the majority of research into the management of DPN pain is focused on the nerves themselves. Various clinical and observational research studies on peripheral nerve injuries used LLLT because it promotes microcirculation in the irradiated area, increases nerve functional activity increases the rate of axon growth and myelinisation and improves regeneration of the injured nerve20, 21,22,23. In addition, LLLT has also been used for the handling of other diabetic complications, such as foot ulcers24, diabetic microangiopathy and wound healing25. Therefore the objective of this study is to evaluate the effect of LLLT on pain intensity and foot skin microcirculation in patients with painful DPN. Methods: After abstaining approval by the Institutional Ethical Committee (IEC) and informed written consent from the subjects, 19 T2DM subjects were screened for DPN in an outpatient setting using Michigan Neuropathy Screening Instrument (MNSI), Vibration Perception Threshold (VPT) using Biothesiometer and DPN was assessed using Visual Analog Scale (VAS). Subjects with T2DM with clinically detected DPN on analgesics, antidepressants were recruited in the study and medications remained unchanged for at least 2weeks. Subjects with malignancy, thyroid disease or other neurological problems, pregnancy, old fractures of lower leg, metallic implants and alcohol or drug abuse were excluded from the study. The detailed clinical evaluation was done to identify the evidence of dry skin, callus formation, fissures, ulceration or deformities like hammer toes, overlapping toes, hallux valgus, prominent metatarsal heads. MNSI was administered following clinical evaluation consist of two components.During the examination, subject�??s foot was inspected for abnormalities in the foot. Each foot with any abnormality received a mark of 1. Each foot was also examined for ulcers and each foot with an ulcer receives a score of 1. The ankle reflexes were elicited. If the reflex is present and it�??s scored as 0, the reflex designated as present with reinforcement and was scored as 0.5. If the reflex is absent and is scored as 1. Vibration sensation tested same as above mention in VPT. Vibration is scored as present if the subject was able to feel within 8Mv and scored as 0, if the subject is able to sense from 15mv- 24mv scored as 0.5 and if the subject was not able to feel or feel in within an above 25mv was scored as 1. The total potential score is 8 and, in the published score algorithm, a score �?� 2.5 is considered presence of DPN. The vibration threshold was examined using Biothesiometer with the subject in supine lying and the result is recorded and >25mVolts is considered presence of DPN Temperature of the foot was examined using Infrared thermal imaging was done using infrared thermal camera (GUIDE ® EASIR-4, Wuhan Guide Infrared Co., Ltd., China) with sensitivities of 0.08 and 0.010C, a temperature range between -200C to 2500C and accuracy of ±20C or ±20C of reading. Laser therapy was given (EC LASER 306 ELECTROCARE SYSTEMS& SERVICES PVT.LTS. Chennai-India) with dosage (wavelength 632.8nm, power output 10mw, laser diode 830nm) on the plantar and dorsum of metatarsals and toes of the foot. For 10days and reassessed at the ends of the 10th session by using VAS, MNSI, VPT and temperature by thermal imaging. Data was analyzed using descriptive statistics and paired�??t�?? test. Level of significance was set at p<0.05 is considered presence of DPN Temperature of the foot was examined using Infrared thermal imaging was done using infrared thermal camera (GUIDE ® EASIR-4, Wuhan Guide Infrared Co., Ltd., China) with sensitivities of 0.08 and 0.010C, a temperature range between -200C to 2500C and accuracy of ±20C or ±20C of reading. Laser therapy was given (EC LASER 306 ELECTROCARE SYSTEMS& SERVICES PVT.LTS. Chennai-India) with dosage (wavelength 632.8nm, power output 10mw, laser diode 830nm) on the plantar and dorsum of metatarsals and toes of the foot. For 10days and reassessed at the ends of the 10th session by using VAS, MNSI, VPT and temperature by thermal imaging. Data was analyzed using descriptive statistics and paired�??t�?? test. Level of significance was set at p<0.05. Results: Nineteen T2DM subjects (12 males and 7females) with mean age 49.58 ± 6.89 were examined and DPN with mean duration of 7.84 ± 3.77 years. Table 1 shows the demographic characteristics of the T2DM subjects. The efficacy parameter was the change in VAS, MNSI, VPT and temperature before and after the low level laser therapy (LLLT). All the subjects showed a significant improvement in symptoms after the therapy. Pain in VAS scale was significantly reduced from 6.47 ± 0.84 to 1.21 ± 0.78 (p<0.001). Whereas MNSI score was also showed a significant reduction from 5.52 ± 1.26 to 2.71 ± 0.97 (<0.001).Vibration perception threshold also reduced post laser therapy from 32.68 ± 6.08 to 24.84 ± 4.29 (<0.001). Significant increase in the temperature of the foot was observed from 30.01 ± 2.11 to 31.75 ± 1.03 (p=0.001). Discussion: DPN is one of the commonly seen complications in subjects with T2DM. From a pathophysiological standpoint, DPN is derived not only from injury to peripheral nerves, most commonly of micro vascular origin26,27. So the treatment of DPN pain could be directed to improve microcirculation, enhance regeneration of nerve injury and reduce pain. The present study tested LLLT to determine its effect on subjects with painful DPN. The study results showed statistically and clinically significant reduction in the DPN pain. Pain was significantly reduced after LLLT, the possible explanatory factor for reduction in pain is due to increased blood supply to the periphery28. The degree of improvement in the blood circulation is comparable with the previously published data28,29. LLLT stimulates the release of cytokines and growth factors into the circulation which are responsible for the vasodilatation of the vessels and formation of new capillaries. This results were supported by the results found in a study conducted by Funk et al. who documented the induction of increased levels of cytokines such as IL-1α, IL-2, IFN-γ and TNF- α after they exposed to HeNe laser30,31. Subjects received LLLT had a significant decrease in the pain level through 7days treatment. Many studies reported significant reduction with LLLT in acute and chronic painful conditions32, 33. But the exact mechanism is remains unclear. I t may be due to increased blood supply by vasodilatation , increased ATP production by mitochondria and increased cellular oxygen consumption by nerve regeneration. LLLT increases blood circulation to the periphery where, in the present study we used Infrared thermal camera to examine the foot temperature. Infrared thermal camera is a non-invasive, convenient, non-harmful and indirect method of quantifying skin blood circulation. Our results not only supports the previous finding about the improvement of microcirculation at the irradiation site but also suggest the possibility of causing systemic effect on microcirculation29. Many studies reported that neuropathic pain was associated with depression. In line with previous study, subjects in the present study were on antidepressant medications, after the LLLT all the subjects discontinued taking antidepressant agents due to significant reduction in pain. LLLT can effectively reduce neuropathic pain thereby by increasing the microcirculation to the nerves. Conclusion: The present study conclude that LLLT can be used as an effective therapeutic modality in the treatment of DPN in that it is able to reduce neuropathic pain, increase microcirculation. Also LLLT can reduce the symptoms of depression which is caused due to neuropathic pain and this can help in discontinuing antidepressants.
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