High-Power Laser Versus Pulsed Eectromagnetic Therapy on Pain and Hoffman Reflex in Lumbar Radiculopathy.

Lumbar radiculopathy is one of the most common complaints evaluated by a spine surgeon. Its prevalence has been estimated to be 3%-5% of the population, affecting both men and women. Age is a primary risk factor, as it occurs secondary to the degenerative process within the spinal column. Symptoms typically begin in midlife, with men often affected in the 40s while women are affected in the 50s and 60s. Disc herniation is one of the primary causes of lumbar radiculopathy.

The pressure exerted by the herniated disc on the longitudinal ligament and the local inflammation results in localized back pain. The lumbar radicular pain arises when disc material exerts pressure or contacts the thecal sac or lumbar nerve roots, resulting in nerve root ischemia and inflammation. The annulus fibrosus is thinner on the posterolateral aspect and lacks support from the posterior longitudinal ligament, making it vulnerable to herniations. Due to the proximity of the nerve root, a posterolateral herniation is more likely to result in nerve root compression.

High Intensity Power Laser (HILT) delivers high-intensity light energy to deep tissues in short pulses (120-200 µs). It causes minor and slow light absorption by the chromophores, which increases mitochondrial bioenergetics by causing extra adenosine triphosphate synthesis and oxygen consumption, as well as RNA and DNA production, resulting in tissue stimulation. Various studies have shown that laser light has anti-inflammatory and analgesic effects and that it reduces edema. HILT also has photothermal properties, resulting from the transformation of high-energy light into heat in tissue.

Magnetic therapy is considered as a safe, easy and non-invasive physical therapy modality used to treat pain, inflammation and other types of pathologies and diseases. Pulsed electromagnetic field (PEMF) refers to a basic law of electromagnetism that describes how a magnetic field interacts with an electric circuit to produce an electromotive force known as electromagnetic induction. Exposure to PEMF has been reported to modulate neuronal excitation and neurogenesis related to Na+ channel activity. Neurons excited by the exogenous electromagnetic force can also affect neighboring cells by ephaptic interaction. They also modulate levels of various growth factors that prevent autoimmune disease and inhibit tissue degeneration.

The H-reflex or "Hoffmann reflex" is obtained by electrode stimulation of the posterior tibial nerve in the popliteal space-at a slow rate with long duration-submaximal electrical shock, and recorded with surface electrodes over the gastrocnemius-soleus complex. The impulse travels up the sensory fibers to the spinal cord, synapses with the alpha motor neuron and returns down the motor fibers to the calf muscle. H-reflex latencies are long, in the 40 to 45 msec range. They are mostly carried out in the S1 root distribution and cannot be recorded consistently from other muscles.