Pain Modulation: Lower Back Pain Case Study

The complete eradication of chronic pain is rarely achieved and is not the goal of most interventions. The goal is the modification of pain to a tolerable level. A comprehensive pain management program utilizes an array of modalities to accomplish this goal.

Nonpharmacological methods are usually adjunctive therapies and do not necessarily substitute for pharmacological interventions. For the chronic pain population, the optimal techniques are those that can be used by the patient in the home setting, are active rather than passive, and can be used for the shortest time possible or gradually weaned.

Tanscutaneous electrical nerve stimulation - TENS, biofeedback, and thermal modalities fulfill these criteria. Pain modulation techniques take advantage of the body's endogenous pain-modulating abilities first postulated and implied by the gate theory of pain of Melzack and Wall.

This theory supports the observation that a direct correlation does not always exist between the extents of organic injury and the expression of pain. Melzack and Wall proposed that pain information was modulated at the level of the "target cell" in the substansia gelatinosa, or laminae II and III of the dorsal horn, by afferent information from A delta and C sensory fibers.

This gaiting effect on the target cell modulates input before it evokes pain perception. Since the description of the gat theory, modulation events higher in the neuroaxis and modulation by descending or efferent mechanisms have been proposed.

Pain modulation occurs at the periaqueductal gray area of the midbrain by descending efferent tracts. The modulation of pain information and pain perception occurs at multiple sites along the neuroaxis and by afferent and efferent pathways.

The pain modulation network can be activated by the administration of spinal opiates. It can also be activated by electrical stimulation (transcutaneously or percutaneously) to peripheral nerves, or epidurally at the level of the spinal cord or brain.

Lets take the most popular type of pain prevalent in the majority of the population - Low Back Pain. Most patient with discogenic low back pain responds to conservative management. Studies show that most patients with low back pain can be treated using non-surgical treatment.

Surgery is considered when definite radiculopathy and neurological deficits are present, especially when they are persistent or progressive. However, in the spectrum of discogenic low back pain, patients in this group are a definite minority.

Progressive and significant neurological deficits justify early surgical intervention. Large midline disc protrusions with cauda equina syndrome require urgent treatment and decompression.

The success of surgical treatment is greatest when there are bona fide objective neurological deficits. With proper patient proper selection, about two-thirds have excellent results, and half of the remaining one-third has improvement to some extent.

However, in many patients with back pain, the major difficulty is radiculopathy. Most of these patients respond to conservative management. Lumbar laminectomy and disketomy for the sole complaint of low back pain are often unjustified.