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13 Articles in Volume 11, Issue #3
Advances in Cranial Electrotherapy Stimulation
Chronic Migraine: An Interactive Case History, Part 3
Cost-effectiveness Of Treatments for Low Back Pain
Electrical Me
Lessons From The Father of Electromedicine — Dr. Luigi Galvani
Medications for Chronic Pain—Nonopioid Analgesics
Pulsed Radio Frequency Energy As an Effective Pain Treatment
The Role of Body Posture In Musculoskeletal Pain Syndromes
The Role of Body Posture In Musculoskeletal Pain Syndromes
Therapeutic Laser for the Treatment of Chronic Low Back Pain
Tolerance to Opioids
Understanding Electromagnetic Treatments
Update: Clinical Challenges in the Diagnosis And Management of Fibromyalgia

Therapeutic Laser for the Treatment of Chronic Low Back Pain

Researchers have noted multiple biochemical and physiologic effects of laser irradiation, including the anti-inflammatory effects, pain modulation, and accelerated tissue healing. These effects make laser therapy a safe and effective option for pain practitioners.

I first discussed some of the important aspects of low back pain and the use of therapeutic laser treatment protocols in the January 2007 issue of Practical Pain Management.1 I am revisiting the subject of chronic low back pain in this article because of new information about the relationship between chronic pain and brain atrophy.2 Tracey and Bushnell are using relatively new, noninvasive neuroimaging and electrophysiologic technologies to study how both acute and chronic pain affect signal processing (functionality), metabolic activity, and structural changes in the human brain.3

To date, various chronic pain conditions have been investigated, and a common finding is that, at some undetermined point in time, there is a degeneration of gray matter volume and density in critical brain regions that may become irreversible. Related research during the past decade has uncovered 3 trends establishing chronic pain as a brain disease (see Table 1). It is hypothesized that this may be due to excitotoxicity and inflammatory processes that result ultimately in neurodegeneration.4

Table 1. Three Trends That Established Chronic Pain as a Brain Disease

Low Back Pain

Low back pain continues to be epidemic, affecting 75% to 85% of all Americans at some point during their lifetime.5 The vast majority of acute low back pain is the result of injuries such as sprain or strain, whereas the cause of chronic low back pain is multifactorial.5 Chronic low back pain is defined as pain of more than 3 months’ duration. It occurs in 2% to 8% of those who experience low back pain.5

The exact causes of chronic low back pain continue to be a mystery. Recent scientific studies have implicated a number of chemical mediators as possible contributors to the production of chronic low back pain.6 These include:

  • Somatostatin
  • Pro-inflammatory cytokines such as interleukin (IL)-1, IL-6, IL-10, and tumor necrosis factor (TNF)–alpha
  • Prostaglandin E2 (PGE2)
  • Nitric oxide

Patients with chronic low back pain may also have emotional factors, such as depression. Studies have shown that 62% of the patients treated at pain clinics for low back pain have some type of depression.7

Biochemical Effects

Table 2. Biochemical Responses to Laser Therapy

There are a number of biochemical effects that have been observed with laser therapy/phototherapy.8,9 Several of these effects relate directly to the management of the patient with chronic low back pain. Three of the most prevalent features of patients suffering from chronic low back pain are inflammation, pain, and edema.6 Injured cells and tissues generate enzymes that encourage the receipt of photons more readily than healthy cells and tissues do. Primary photoacceptors, which are activated by light, are thought to be flavins, cytochromes, and porphorins.10-11

These photoacceptors are located in the mitochondria and can convert light energy into electrochemical energy. Chromophores, in the form of porphyrins, have been shown to play an important role. Small amounts of singlet oxygen have been shown to accumulate in tissues irradiated with laser light.8 Singlet oxygen affects the formation of adenosine-5’-triphosphate (ATP) in the mitochondria12-20 (see Table 2).

Research in laser and light therapy has documented that red and near infrared light reduce pain by a combination of these responses (see Figure 1).21-23

Neurologic Response

There are several neurologic responses to laser therapy that may influence brain recovery or prevent brain atrophy as well as several of the physiologic effects listed above. Oron et al studied the effects of gallium arsenide (GaAs) laser irradiation on ATP production in normal human neural progenitor (NHNP) cells.24 Tissue cultures were treated with the GaAs laser, and ATP levels were determined 10 minutes after laser application. The quantity of ATP in the treated cells was significantly higher than in the nontreated group. The application of laser to NHNP cells significantly increases ATP production (P<0.05). This may explain the beneficial effects of low-level laser therapy (LLLT) in stroked rats.24

Trimmer et al performed an in vitro study showing that a single, brief treatment with a gallium-aluminum-arsenide (GaAlAs) laser increased the velocity of mitrochondrial movement for 2 hours in cells taken from patients with sporadic Parkinson’s disease (PD).25 Treatment sped the velocity of mitrochondrial movement up to levels approximating those of disease-free, age-matched cells. Their findings provide early-stage confirmation that laser therapy has the potential to improve neuronal function in many patients with PD and other neurodegenerative diseases.25

Schiffer et al studied 10 patients with major depression. Each patient was given a baseline standard diagnostic interview, a Hamilton Depression Rating Scale (HAM-D), a Hamilton Anxiety Rating Scale (HAM-A), and a Positive and Negative Affect Schedule (PANAS).26 Patients were then randomly given four 4-minute treatments: near infrared (NIR) light radiation to left forehead at F3, to right forehead at F4, and placebo treatments (light off) at the same sites. Immediately following each treatment, PANAS was repeated, and at 2 and 4 weeks posttreatment, all 3 rating scales were repeated. At 2 weeks posttreatment, 6 of 10 patients had a remission (score ≤10) on the HAM-D, and 7 of 10 achieved remission on the HAM-A. Patients experienced highly significant reductions in both HAM-D and HAM-A scores following treatment, with the greatest reductions occurring at 2 weeks.

This small feasibility study suggests that NIR photobiomodulation (PBM) may have utility for the treatment of depression and other psychiatric disorders and that double-blind, randomized, placebo-controlled trials are indicated.26

Figure 1. Flowchart of some of the most commonly observed biochemical effects of therapeutic lasers.Figure 1. Flowchart of some of the most commonly observed biochemical effects of therapeutic lasers. (Figure courtesy of MedicalQuant). ATP, adenosine-5’-triphosphate; DNA, deoxyribonucleic acid; RNA, ribonucleic acid.

Tissue Penetration and Saturation

Chronic low back pain is a complex clinical condition that involves many different tissue levels—from subcutaneous and muscle tissues to the deeper tendons and ligaments, including the intervertebral disc. Laser therapy, if it is to be effective, must be applied in a way that will produce significant biochemical changes in the superficial, medium, and deep tissues. Red light will affect the skin and subcutaneous tissue to an approximate depth of 1 cm. Infrared light will affect deeper tissue structures from 1 to 5 cm depth. Comprehensive laser/light therapy for treating chronic low back pain must therefore include the use of both red and infrared wavelengths.

A GaAs superpulsed infrared laser, or high-output GaAlAs infrared laser, is necessary to obtain the deep tissue penetration needed to effectively treat the deeper structures of the back. Gruszka, using a GaAs superpulsed laser, found that 9 joules/cm2 of energy applied to appropriate points was effective at ameliorating pain in patients with herniated lumbar discs and radiculopathy.27 Most modern diode lasers use preprogrammed treatment settings that help ensure that adequate numbers of joules of light energy will be irradiated into the patient’s tissues. Tasaki found that pain relief was obtained in patients using a GaAlAs laser in the 30 to 80 mW output range.28 Reductions in the size of lumbar disc herniation have been demonstrated by Gruzska, Tatsuhide, and others.29 Tertiary effects by treating acupuncture points have been shown to be effective at decreasing low back pain. Nikolic found that treating acupoints with a 630-nm red laser was most effective.30

The results of laser therapy will be maximized by combining several laser techniques. Clinicians have found tissue saturation of the affected area of the low back to be the best place to begin. Stimulation of acupoints and/or reflex points is also valuable. The irradiation of lymphatic structures is beneficial, especially when edema is present. Pulse frequency is of some importance, especially when using a GaAs superpulsed laser.31 Pain relief is best achieved in the frequency range of 1 to 100 Hz. Inflammation responded well to the 3000- to 5000-Hz range. Edema responds well to 1000 Hz (see Table 3).

Table 3. Pulse Frequency SettingsFigure 2. Image Courtesy of MedicalQuant-West.

The amount of time it takes to adequately treat an area of involvement (therapeutic levels of joules of photon energy) in the low back depends on the size of the area and the power output of the laser/light therapy device. This is known as photon or power density (see Figure 2). Table 4 can be used as a general guide for average duration of treatment at different penetration depths versus laser power output.12

Table 4: Treatment Time

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Treatment Modality

A typical treatment approach for a patient with chronic low back pain would involve the following:

1. History of the condition and physical examination of the low back, paying particular attention to the level of abnormal muscle, nerve, and joint function, as well as pain level. This would include lumbar and pelvic range of motion, lumbar and pelvic orthopedic tests, lower extremity deep tendon reflexes, and Visual Analogue Scale.

2. The initial treatment aim is to saturate the primary area of involvement. A good choice would be to use 3000 to 5000 Hz for 5 to 10 minutes with a GaAs laser to help reduce inflammation. A scanning contact is used for this technique to maximize the tertiary or systemic effects (see Figure 1). Note that treating the lymph nodes proximal to the area of involvement with a 3000 Hz laser emitter using a pumping action—prior to treating the area of involvement—will enhance the reduction of edema (see Figure 2).

3. The secondary treatment aim is to reduce pain and stimulate healing in the deeper tissue of the right low back. A GaAs superpulsed laser at 5 to 50 Hz for 5 to 10 minutes is the best choice to get the deepest penetration.1 This is performed with stationary contact with the emitter. Note that patients with chronic low back pain can become exacerbated after the initiation of laser therapy, so it is advisable to use one half of the above dose during the first treatment and until the individual patient’s response can be determined on the first follow-up visit (see Figure 3).

4. A third technique often applied during a treatment session is stimulation of acupoints with the laser emitter. The exact points used are dependent on the clinician’s training and experience with acupuncture or acupressure. Treatment involves stimulation of each acupoint for 1 minute at 1000 Hz (see Figure 4).

Laser therapy treatment usually lasts 10 to 20 minutes per session. Chronic low back pain patients will usually respond best to 3 to 4 treatments per week. Maximum effect is often reached in 3 to 4 weeks, but several months of care may be necessary in extremely complex cases. It is important to allow for both delayed and cumulative effects, which commonly occur in patients receiving laser therapy. Treating a patient too frequently actually can slow down the recovery process and increase symptoms.2 Although laser therapies can often produce results as a stand-alone therapy, they also work very well adjunctively with other therapies, such as physical therapy, manipulation, exercise, and stretching. The wound-healing effects of therapeutic lasers are well documented in laser-related literature, suggesting it is also a valuable adjunct during postoperative recovery.3 Laser therapy is extremely safe and has few contraindications, as described in Figure 5.

Conclusion

Therapeutic lasers and other phototherapy devices have been shown to be safe, often effective, easily used primary or adjunctive therapy that is relatively cost-effective to both the clinician and patient. The multiple biochemical and physiologic effects of laser irradiation, including the anti-inflammatory effects, pain modulation, accelerated tissue healing, and immune and neurological modulation mentioned in this article, are cause for contemplation and further investigation, especially as they relate to the possible causal and developmental factors of brain atrophy in chronic pain patients.

There are 2 types of responses that have been observed in laser-related research regarding chronic pain that are especially interesting: effective pain modulation and alterations in brain function, such as increased cerebral blood flow and blood flow velocity.31 If chronic pain indeed causes brain atrophy, we owe it to our pain patients to explore every possible clinical modality and procedure that may prove to be an asset in preventing or controlling this condition.

 

Last updated on: November 28, 2011
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