Spine Surgeon Partner
Bottom Line – Pain, motor weakness, and paresthesias of neurogenic origin can only come from one of two places, either the central nervous system or the peripheral nervous system. Once the central nervous system has been ruled out, it’s a peripheral nerve problem until proven otherwise. A significant amount of pathology that has traditionally been viewed as “coming from the spine,” particularly the low back, actually involves the peripheral nervous system.
Generally speaking, the default position of most physicians is to consider the presence of radiating pain, motor weakness, or paresthesias in the shoulder/pelvic girdles and upper/lower extremities to be due to “a spine problem,” period. This view has thrived mainly due to a widespread lack of knowledge regarding detailed peripheral nerve anatomy and how peripheral nerve problems typically present. While CT and MRI imaging can render detailed views of the skull, brain, spine, spinal cord, and nerve roots, allowing for close examination of these structures, no such corollary exists for interrogating the peripheral nervous system. Practically speaking, peripheral nerves are essentially “invisible” to the same imaging systems that give such detailed information regarding the components of the central nervous system. In addition, although regularly utilized, electromyography and nerve conduction studies tend to add little diagnostic information in the setting of complex peripheral nerve pathology.
Compounding these issues is the fact that overwhelmingly, the main byproduct of peripheral nerve pathology is essentially chronic pain. The history of pain management has, to a greater or lesser degree, been the story of “one size fits all.” While pain medication has been very successful in the area of treating acute pain, for many patients suffering with chronic pain, it has failed miserably. Despite this reality, a dogged persistence in doling out narcotics, primarily for lack of a better option, has remained the approach for treating the chronic pain patient.
General physician ignorance regarding peripheral nerve anatomy, the lack of reliable techniques to obtain “objective” data about peripheral nerves, and the traditional focus on managing symptoms, the pain, rather than trying to discover and eliminate the source, the pain generator, has essentially resulted in the peripheral nervous system assuming the role of a medical “black box.” The key to stripping the shroud of mystery away from the peripheral nervous system is to have an intimate knowledge of peripheral nerve anatomy. This is really the “Rosetta Stone” that unlocks the secrets of many chronic pain problems which have traditionally been considered untreatable.
For the spine surgeon in particular, trying to diagnose the source of pain in a patient whose primary issue involves upper or lower extremity pain, by relying solely on MRI imaging or physical exam maneuvers designed to unmask or confirm a radiculopathy, without having a clear picture of the status of the peripheral nervous system, certainly increases the risk of error. Very often a patient may have a lesion at the spine level coexisting with one or more peripheral nerve compressions or peripheral nerve damage. Operating on the spine will likely resolve the spine issue but may leave the patient unsatisfied if the peripheral pain remains. In situations where the peripheral pain is not clearly due to a radiculopathy, having the patient undergo a comprehensive peripheral nerve evaluation can set realistic expectations for both the spine surgeon and patient in terms of what’s achievable with spine surgery alone. Likewise, if a patient who has already undergone spine surgery and demonstrates no further compressive lesions at the spine level, continues to experience peripheral symptoms, then the spine surgeon can discuss the possibility of ongoing peripheral nerve pathology and refer the patient for consultation. This tends to increase patient satisfaction while at the same time making life easier on the spine surgeon.
For the spine surgeon, keeping the possibility of a peripheral nerve lesion at the forefront of the differential diagnosis, especially in patients with extremity pain or “atypical” pain symptoms from a spine standpoint, is always a good idea. In reality, any patient who has undergone the prescribed course of treatment or surgery from a spine approach, or who clearly has no identifiable lesion involving the spine, but who still experiences extremity or lumbosacral low back pain is a good candidate for a peripheral nerve evaluation.