Mechanical stimulation of the disc (touching the disc or pressure on the disc) can cause back pain but not leg pain. Pain down the leg is a sign that the spinal nerve root is being compressed or irritated as it leaves the spinal cord. A herniated disc can cause this type of spinal nerve root compression. A damaged disc can also release chemicals that irritate the spinal nerve roots.
But very often, the back pain is a separate problem from the leg pain. Removing the disc removes the compression and irritation on the spinal nerve root. Suddenly the shooting pain down the leg is gone. But when the back pain remains, it’s a sure sign that something else is going on.
And that something else could be anything affecting the spinal ligaments, spinal joints, tendons, muscles, or other soft tissue structures in the spine. Finding the cause of the separate back pain can be difficult. Imaging studies such as X-rays, MRIs, ultrasonography, and CT scans may not show any changes in the soft tissue structures that point to the underlying problem.
Scientists are working hard to unravel the complexities of the nervous system — especially as it relates to back pain that doesn’t go away easily or with a variety of treatment approaches. Surgeons try to avoid operating if there’s a large chance that the surgery won’t yield the desired results (pain relief).
Physicians must carefully evaluate each patient individually. The goal is to determine the type of pain patterns present and their cause(s) before selecting the most appropriate and successful treatment.