Herniated Lumbar Disc Symptoms
The most common symptoms of a herniated disc are back and leg pain. The location of the leg pain depends upon which nerve is pinched. There are five discs and vertebral bones in the lumbar spine. These are numbered from the top down. The discs are numbered by the bones they separate. Each nerve lies on the behind and slightly above the disc and exits the spine from the side. Due to the position of the nerve it is very common for a disc herniation to actually pinch the nerve just below the disc. For example, a L4/5 disc herniation will often pinch the L5 nerve more than the L4 nerve. Although each person’s nervous system is unique, there are regular patterns of pain that occur with pinching of each of the individual nerves in the lower back. We call these nerve patterns dermatomes. A dermatome is the area of the leg that the nerve travels to. There are dermatomal “maps” that show the general area covered by each nerve. In the above example of an L4/5 disc pinching the L5 nerve, the pain and numbness generally travels to the side of the calf into the top of the foot. As the L5 nerve is also responsible for the muscles that lift the toe and foot, in more severe disc herniation the person can develop weakness of these muscles resulting in a “drop foot”.
The pain from a disc herniation can start very abruptly or more slowly over a period of time. In larger acute disc herniations, the tissue of the disc quickly pinches the nerve causing a rapid onset of symptoms. This often occurs with lifting heavy objects or injuries. In this case the person almost immediately knows that something is wrong as their back and leg become painful very quickly. Other times, the person will notice a period of back or hip pain that gradually becomes worse and over a period of days or weeks will more gradually develop pain and symptoms into the leg. There are many theories trying to explain the different characteristics of disc herniations. One thought is that with very acute onset, that the mechanical effect of the disc tissue upon the nerve causes the sudden pain. In the case of more gradual onset of symptoms, it may be that the inflammation caused by the herniated disc is a more important cause of the pain. As inflammation and swelling of the disc and nerve do not occur immediately, it takes time for the nerve to become gradually pinched by the disc herniation.