BIOPHYSICAL AND PHYSIOLOGICAL MECHANISMS OF LOW ENERGY LASERS INTERACTIONS WITH LIVING CELLS AND THEIR IMPLICATIONS IN PAIN TREATMENT

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1 ANALELE ŞTIINŢIFICE ALE UNIVERSITĂŢII AL. I. CUZA IAŞI Tomul I, s. Biofizică, Fizică medicală şi Fizica mediului 2005 BIOPHYSICAL AND PHYSIOLOGICAL MECHANISMS OF LOW ENERGY LASERS INTERACTIONS WITH LIVING CELLS AND THEIR IMPLICATIONS IN PAIN TREATMENT Laura Marinela Ailioaie 1, D.A. Chiran 2, C. Ailioaie 3 KEYWORDS: pain, biophysical mechanisms, low energy lasers, low level lasers. The biostimulative effects exerted by various low energy lasers in the visible and infrared range are used in medicine for treating a wide range of pathological conditions. Low level laser therapy (LLLT) is effective in a number of clinical situations e.g. pain relief, soft tissues injuries, severe wounds and more. 21 patients aged years were included in the study, and divided randomly into two groups. The main inclusion criterion was the diagnostic of pain, as a consequence of one of the following conditions: posttraumatic pain, myofascial pain, lumbalgia, cervical pain, sciatica, neuralgia, peripheral neuropathy, mononeuropathy, radiculopathy, myelopathy, wounds and fractures. Group I (11 patients) received LLLT together with conventional medication and physical therapy. The control group (Group II 10 patients) was submitted only to classical treatment. The evaluation was based on objective criteria, as well as on a subjective self-assessment, which was graded under four categories (very good, good, satisfactory, no influence). The successful treatments were up to 81.8% of the patients in the group I, and of 60% in the control group, treated only by conventional therapy. The mechanism and effectiveness of LLLT should be considered as an extension to the accepted physiotherapy modalities. 1. INTRODUCTION Phototherapy is based on the effects of light energy on cell metabolism of living systems. It has long been assumed that visible and near infrared light cannot interact with non-pigmented and non-stained tissues. Nowadays the biostimulative effects exerted by various low energy lasers in the visible and infrared are used in medicine for treating a wide range of pathological conditions [1-3]. Low level laser therapy (LLLT) is effective in a number of clinical situations (e.g. pain relief, soft tissues injuries, severe wounds and more), but the photobiological basis of this therapy is not yet well understood. The most important question is why a human body responds to this therapy and how both visible and infrared radiations can trigger similar results clinically, that have been shown to be beneficial, even though these two radiations differ dramatically in their photophysical properties [4]. 1 Al. I. Cuza University of Iasi, Faculty of Physics & Laser Clinic, Iasi. 2 Gr. T. Popa University of Medicine and Pharmacy Iasi, Faculty of Medicine. 3 Laser Clinic & Gr. T. Popa University of Medicine and Pharmacy Iasi, Faculty of Medicine.

2 LAURA MARINELA AILIOAIE, D.A. CHIRAN, C. AILOAIE 68 Biological responses of cells to visible and near-ir (laser) radiation occur due to physical and/or chemical changes in photoacceptor molecules, components of respiratory chains (T. Karu) [3,4]. Some of the major changes induced by laser in the irradiated cell are shown in Fig. 1. Fig.1. Major changes in the cell metabolism induced by laser radiation [3]. Cellular macroeffect is the result of primary reactions, like modulation of PGE. The modulation of PGE 2 levels, increased production of nitric oxide and also of indirect reactions like improved blood flow. The nitric oxide enhances the endogenous opioid system via cgmp. The increased blood flow decreases ischemia, increases oxygen and nutrients levels in the irradiated area and normalizes ATP Na + /K + homeostasis (Fig. 2). There is no single simple definition of pain: however, as with other medical disease entities, pain is usually a symptom of some other physical or even mental Fig. 2 Result of cellular macroeffect (after T. Karu, Lasers in Medicine, p.109 [3] ).

3 69 BIOPHYSICAL AND PHYSIOLOGICAL MECHANISMS abnormality [5,6]. Pain is one of the major reasons for which a patient addresses the physician. To realize that pain is a debilitating disease in its own right has taken hundreds of years for the medical school. Nociceptive experiences during childhood could influence, sometimes dramatically, the architecture and the organization of the cortex through ways not completely elucidated yet (Fig 3). The treatment of pain is of great concern for the modern medicine. Laser therapy is a good solution when it is associated with the classical treatment [7,8]. Study Design 2. PATIENTS AND METHODS In the study were included 21 patients aged years of both sexes. The main inclusion criterion was the diagnostic of pain, as a consequence of one of the following conditions: posttraumatic pain, myofascial pain, lumbalgia, cervical pain, sciatica, neuralgia, peripheral neuropathy, mononeuropathy, radiculopathy, myelopathy, wounds and fractures. Pain was classified according to history, characteristics of pain, manual examination, and radiological findings. The patients were randomly divided into two groups. Group I (11 patients) received LLLT together with conventional medication and physical therapy. The control group (Group II 10 patients) was submitted only to classical treatment. Treatment Protocol Fig. 3. Pathways of Pain to Cortex. LLLT was applied six times weekly, over four weeks, as a complementary therapy. The work was performed with a GaAlAs laser device (670 nm and 830 nm wavelengths), with a modulation frequency from 0 to 15 Hz, in order to obtain the optimal perturbation of the nociceptive transmission. As a rule, each procedure included a localized treatment that involved irradiation with contact technique of the trigger or acupuncture points (Fig. 4), specified in the protocol, and followed by irradiation of larger tissue areas using static irradiation (Fig 5) or scanning laser devices (Fig. 6). The delivered energy varied from 4 J up to 10 J, with an average

4 LAURA MARINELA AILIOAIE, D.A. CHIRAN, C. AILOAIE 70 energy density of 4 J/cm 2. The scanned areas were irradiated for 20 minutes, with an average power density not exceeding 30 mw/cm 2. Fig. 4. IR Laser Irradiation Contact Technique Fig. 5. Visible Laser Irradiation Non-contact Static Technique Fig. 6. Visible Laser Irradiation Scanning Technique Classical medication given to patients consisted in non-steroidal antiinflammatory drugs and physical therapy, and was applied in order to reduce anxiety associated with pain and to stimulate tissue relaxation. Specific aspects of the examination, history, imaging, treatment of patients with pain and evaluation were applied. 3. RESULTS AND DISCUSSIONS The evaluation was based on objective criteria (e.g. restoration of mobility and improved range of motion after several laser procedures), as well as on a subjective self-assessment, which was graded under four categories (very good, good, satisfactory, no influence). Short-term and long-term side effects as well as conditions responding to LLLT were recorded. The successful treatments were up to 81.8% of

5 71 BIOPHYSICAL AND PHYSIOLOGICAL MECHANISMS the patients in the group I, and of 60.0% in the control group, treated only by conventional therapy (Fig. 7) % Group I Group II Fig. 7. Percentage of Patients with positive Outcome at the End of the Treatment LLLT had the following biophysical and physiological effects: Increased vascularity (normalizing the circulation by triggering the formation of new capillaries, which replaced the damaged ones). Stimulated the production of collagen. Stimulated the release of adenosine triphosphate (ATP). Increased lymphatic system activity. Increased RNA and DNA synthesis and thus helped the damaged cells to be replaced more promptly. Reduced the excitability of nervous tissue. The photons of light energy enter the body and call upon the body to send positive ions (like calcium among others) to go to the area being treated. These ions assist in firing the nerves thereby relieving pain. LLLT also induced the effects: Stimulated fibroblastic activity which aids in the repair process. Increased phagocytosis of dead or degenerated cells. Induced a thermal-like effect in the tissue through photo-chemical reactions. Stimulated tissue granulation and connective tissue projections, which are part of the healing process of wounds, ulcers or inflamed tissue. Stimulated acetylcholine release with parasympathetic effects. Stimulated production of endorphins and enkephalins from the brain as well as chemicals from other areas of the body like the adrenals which facilitate long term pain relief. Activated the acupuncture points and induced the relaxation of the muscles. Regarding the side effects of the laser therapy the most important ones are: Sleeplessness

6 LAURA MARINELA AILIOAIE, D.A. CHIRAN, C. AILOAIE 72 Tiredness Nausea / vomiting Euphoria Skin reactions Arrhythmia The results of the study are relevant for the implementation of laser irradiation in patients with acute or chronic pain. All patients in Group I significantly improved their pain status and 81.8% of the subjects in this group had a complete positive outcome compared to only 60.0% of the subjects in Group II. The rest of 40.0% of the patients in the control group displayed inconsistent improvement. 4. CONCLUSIONS The mechanism and effectiveness of LLLT in pain management should be considered as an extension to the accepted physiotherapy modalities. Laser therapy can be successfully associated with classic medication for pain because it increases the efficiency of the treatment. LLLT actions on pain on the free endings level, by preferential stimulation action laser emission on the fibers A alpha, A delta, B beta against the C fibers, which are nociceptive. Other surveys show that an increasing number of physicians are using laser light treatment modalities. Although the percentage is still small, it is growing each year. REFERENCES 1. G.D. Baxter, C. Diamantopoulos, S. O Kane, Therapeutic lasers. Theory and Practice. Churchill Livingstone, New York, T. Oshiro, R.G. Calderhead, Progress in Laser Therapy, London: John Wiley, Z. Simunovic and all, Lasers in Medicine and Dentistry. Zagreb, Croatia, Rijeka:Vitagraf, T. Karu, The Science of Low Power Laser Therapy, Overseas Publishers Association, Amsterdam, L.M. Ailioaie, C. Ailioaie, Biofizica locomotiei umane, Ed. Vasiliana 98, Iaşi, L.M. Ailioaie, C. Ailioaie, A.D. Chiran, Proceedings of the Annual Symposium on Mathematics Applied in Biology & Biophysics, Iaşi, 2004, Tom XLVII, pp L.M. Ailioaie, C. Ailioaie, A.D. Chiran, Laser therapy in neurophatic pain, Proceedings of the Annual Symposium on Mathematics Applied in Biology & Biophisics, Iaşi, 2004, Tom XLVII, pp L.M. Ailioaie, C. Ailioaie, V. Bălteanu, A.D. Chiran, Importance of the lasertherapy and eccentric exercises in Achilles tendinopathy, Rev. Med. Chir. Soc. Med. Nat, Iaşi, 2005, Vol. 109, Supl. Nr. 1, pp , ISSN