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Therapeutic Laser Evolution—Part 2

This retrospective observational study of patients with unresolved wrist pain noted improvements in many quality of life parameters after Hackett-Hemwall dextrose prolotherapy.
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This is part two of the article that Doug Johnson presented in the last issue of Practical Pain Management (October 2008). I am pleased to have contributed to this article because it introduces a new technology that holds great promise for faster and more effective clinical results. I have been using combination laser/phototherapy and electrical stimulation for many months and am finding that has produced unique results beyond what I have previously observed.

William J. Kneebone, CRNA, DC, CNC, DIHom

The recent introduction of Fourth Generation (G4) technology— mechanical and electrical laser hybrids—have inspired a whole new classification of light therapy and opened up a new realm of possibilities. These new technologies offer the promise of improved effectiveness and clinical outcomes.1 However, the research supporting these new combinations remains sparse. One of the most intriguing of these new devices is the laser and electrical stimulation combination. Even with a lack of clinical trials, this newest of the G4 electrical modalities has some practical applications that all laser clinicians should be aware of.


Both electrical muscle stimulation (EMS) and laser therapy have been studied extensively over the last few decades. EMS has long been a clinical favorite of therapists and staple of most rehabilitation centers. The use of transcutaneous electrical nerve stimulation (TENS) as a modality for pain relief dates back to the 1960s—when it was used as a presurgical screening tool for patients with chronic pain in order to evaluate them for possible dorsal column stimulator implantation. Many of those patients experienced substantial relief and did not require dorsal column implatation.2 One of first TENS studies was published in 1966 by Wall and Street.3

Studies historically refer to the gate control theory of pain to explain the effects of high frequency TENS.4 The theory suggests that stimulating large diameter afferent fibers inhibits input from small diameter afferent fibers in the substantia gelatinosa of the spinal cord. A commonly held theory for the mechanism of action of low-frequency TENS is biochemical activation of endogenous opioid pathways. Analgesia produced by low-frequency, high-intensity TENS—but not high-frequency, low-intensity TENS—is reversed by administration of naloxone, an opioid receptor antagonist.5Increased concentrations of beta endorphins have been observed in the blood and cerebral spinal fluid of healthy patients after both low and high frequency TENS.6,7

Clinical studies of TENS have been done on a wide variety of painful disorders. With TENS, Melzack found an average reduction in pain of 75% following peripheral nerve injuries, 66% for phantom limb pain, 62% for should-arm pain, and 60% for low back pain following a brief, intense burst of TENS to trigger points or acupoints.8 Likewise, Meyler et al9 observed pain reduction in 211 patient with various types of painful conditions. These included favorable responses in 53% of peripheral nerve damage sufferers, 75% of ischemic heart disease patients, 69% of patients with mechanical/degenerative musculoskeletal disorders.9 Long term pain relief in patients with chronic pain was evaluated by Fishbain et al.10 They interviewed 506 chronic pain patients that had purchased home TENS devices and found that 74.3% of them had used the devices for six months or longer. These users reported less pain at rest and during activity, decreased use of other therapies such as PT, chiropractic, OT, etc., and decreased reliance on NSAIDs, opioids, anti-inflammatory drugs, or steroids.10 Barr et al11 found that age-related changes in the elderly did not significantly alter the applicability of TENS. There was no difference found in effectiveness or tolerance in these elderly patients with chronic pain.10

Laser therapy, with its minimal contraindications, is gaining some popularity in the rehabilitation market. Enwemeka et al found that laser therapy was highly effective for tissue repair and pain relief12 and Ferreira et al demonstrated its positive effects on the inflammatory process.13 These studies—combined with an ever-expanding body of scientific evidence—validate the conclusion that radiation by red and near infrared light reduces pain by a combination of processes:

  • increase in b-endorphins
  • blocked depolarization of C-fiber afferent nerves14
  • increased nitric oxide production
  • increased nerve cell action potential15
  • axonal sprouting and nerve cell regeneration16
  • decreased bradykinin levels
  • increased release of acetylcholine
  • ion channel normalization17

Though critics of phototherapy may continue to debate its overall effectiveness, the overwhelming scientific and clinical outcomes support the successful use of this new modality. Phototherapy has been shown to be effective in the management of ankle sprains,18 Achilles’ tendonitis,19 shoulder tendonitis,20 medial and lateral epicondylitis,21 cervical pain,22 and wounds/abrasions.23

Figure 1. Method sensitivity S=Zindif / Zactiv versus frequency.

Combined Therapy Effect

While their use as monotherapies has been extensively investigated, the combined application of both laser/light and electrical muscle stimulation research is just in the initial stages. Clinical trials of the FDA-cleared LaserStim24 were conducted at the Burdenko Head Veterans/Military Clinical Hospital by V.M. Kliujev in Moscow, Russia. A group of 68 patients, suffering from osteochondrosis of cervical, thoracic and lumbosacral sections of the vertebral column and accompanied by moderate cervicalgia, thoracalgia, lumbalgia, were treated with a combined therapy of laser and LED radiation in a static magnetic field. In the case of acute pain syndromes, a pulse electrical current was used in addition to the magnetic field and laser radiation

The researchers reported that all patients endured the treatment procedures and noted that, in the middle of the treatment course, the pain syndrome intensity significantly decreased and, at the end of the course, the pain syndrome essentially regressed while joint mobility increased. Myofascial pain syndrome associated with acute radiculitis was improved. In cases of radicular syndrome and polyneuropathy, greater improvement was provided by the use of light and infrared laser radiation in a static magnetic field in combination with a low frequency pulse electric current. A favorable therapeutic effect as a result of LaserStim use was obtained in 82% of patients with a satisfactory effect in 18% of patients. No negative results were observed.

G4 Hybrid Technology

Acupuncture shares some similarities to laser/light therapy applications. Many successful phototherapy treatment protocols are derived from acupuncture therapies.25 In fact, Dr. Kneebone, in a prior article in this journal, discussed a variation on laser therapy called laser acupuncture.26

Last updated on: January 4, 2012
First published on: November 1, 2008