Laser treatment of sciatica and autonomic effects

It was brought to my attention by my colleague that laser through the lumbosacral junction can produce a transient sensation of warmth in the lower extremity and that this phenomenon can be useful in the treatment of sciatica or radicular pain.

One theory to explain the distant thermal changes caused by laser is via its effects on the sympathetic chain and ganglia¹. The effects of laser of the lumbar sympathetic ganglia on raising skin temperature in the legs has been published previously², and similar reports have noted the warming effects of laser in the upper extremity (or entire body) seen when the stellate ganglion is targeted in the neck using phototherapy^1,3,4. In a rat model, infrared light targeting the lumbar sympathetic ganglia has been shown to have anti-nociceptive effects in treatment of sciatic nerve injury⁵. One author states that the effects of laser on the sympathetic ganglia leads to parasympathetic dominance, relaxation of arterial walls, and oxygenation of tissues¹.

Treatment of sciatica using laser: Knowledge of neuroanatomy will aid in targeting specific structures of the lumbar spine. Flexion of the lumbar spine may boost penetration depth and allow for the thermal effects in the lower extremity and anti-nociceptive benefits. At the time of this photograph, the patient (me) felt warmth in the right anterior thigh and anteromedial leg.

 This phenomenon could be analogous to the warming effects seen with anesthetic sympathetic blockade, which is used to alleviate neuropathic pain⁶. There is growing evidence that the sympathetic nervous system is an integral component of lumbosacral radicular pain⁷, and thus could become an important therapeutic target for this condition.

We have found that the lower extremity warming induced by laser is very pleasant and often inhibits pain. A patient I treated today with a lumbar disc herniation stated that it felt like he was "in a hot tub". It is important to note that there is another phenomenon that can occur called a laser evoked potential. This happens when the energy from the laser stimulates an action potential and may be slightly painful⁸. The tool we use to elicit the warming effects is a 30W dual-wavelength (810 & 980nm) GaAlAs laser, while lasers designed to elicit action potentials and muscle twitch responses have a much higher wavelength^9,10.

The recognition of the ability of laser to effect the sympathetic nervous system is important in treatment of sciatica and lumbosacral radiculopathy because there are so many diverse etiologies and pathomechanisms of pain. Laser has been shown to be beneficial in treatment of lumbar radiculopathy¹¹ and in my opinion the phenomenon described above could partially explain why.

1.            Ohshiro, T. The Proximal Priority Theory: An Updated Technique in Low Level Laser Therapy with an 830 nm GaAlAs Laser. LASER Ther. 21, 275–285 (2012).

2.            Ide, Y. et al. [Effects of linear polarized light irradiation around the lumbar sympathetic ganglion area upon the skin temperature of lower extremities]. Masui. 56, 706–707 (2007).

3.            Otsuka, H., Okubo, K., Imai, M., Kaseno, S. & Kemmotsu, O. [Polarized light irradiation near the stellate ganglion in a patient with Raynaud’s sign]. Masui. 41, 1814–1817 (1992).

4.            Wajima, Z., Shitara, T., Inoue, T. & Ogawa, R. [Linear polarized light irradiation around the stellate ganglion area increases skin temperature and blood flow]. Masui. 45, 433–438 (1996).

5.            Muneshige, H. et al. Antinociceptive effect of linear polarized 0.6 to 1.6 microm irradiation of lumbar sympathetic ganglia in chronic constriction injury rats. J. Rehabil. Res. Dev. 43, 565–572 (2006).

6.            K M Tran, S. M. F. Lumbar sympathetic block for sympathetically maintained pain: changes in cutaneous temperatures and pain perception. Anesth. Analg. 90, 1396–401 (2000).

7.            Mizuno, S. et al. The effects of the sympathetic nerves on lumbar radicular pain A BEHAVIOURAL AND IMMUNOHISTOCHEMICAL STUDY. J. Bone Joint Surg. Br. 89-B, 1666–1672 (2007).

8.            Quante, M., Lorenz, J. & Hauck, M. Laser-evoked potentials: prognostic relevance of pain pathway defects in patients with acute radiculopathy. Eur. Spine J. 19, 270–278 (2010).

9.            Wells, J., Konrad, P., Kao, C., Jansen, E. D. & Mahadevan-Jansen, A. Pulsed laser versus electrical energy for peripheral nerve stimulation. J. Neurosci. Methods 163, 326–337 (2007).

10.          McCaughey, R. G., Chlebicki, C. & Wong, B. J. Novel wavelengths for laser nerve stimulation. Lasers Surg. Med. 42, 69–75 (2010).

11.          Konstantinovic, L. M. et al. Acute low back pain with radiculopathy: a double-blind, randomized, placebo-controlled study. Photomed. Laser Surg. 28, 553–560 (2010).