Lumbar radiculopathy involves the symptoms of lower back pain as well as pain that radiates down the hip(s) and leg(s) as a result of irritation or compression of the nerve roots in the lumbar spine or the nerve roots between the last lumbar vertebra (L5) and the first sacral body (S1). The nerve roots associated with lumbar radiculopathy are the spinal nerves that leave the spine, either through the intervertebral foramina or the sacral foramina of the sacrum. These spinal nerves may be irritated or compressed for a number of reasons, though disc herniations are the back conditions that are the most often responsible for this condition. A disc herniation, or herniated disc, is an intervertebral disc in which the outer membrane (annulus fibrosis) becomes torn or ripped causing the inner material of its core (nucleus pulposus) to seep out. This material is not easily reabsorbed by the body, so when it leaks through a tear in the disc it tends to just stay there, possibly affecting the structures around it. When this disc material pushes towards the back of the disc and into the nerve root, it may result in pain in that level of the back, as well as pain along the pathway that nerve travels. Because the spinal nerves in the lower part of the lumbar spine travel as far as the lower leg and feet, nerve root compression in these nerve roots may result in pain and weakness that radiates down to the bottom of the leg.
Lumbar Radiculopathy often involves back pain with associated radiating pain down one or both legs. This condition may also involve a neurologic component to the condition, involving symptoms such as burning pain, muscle weakness, numbness, and tingling in these same structures. When neurologic conditions are also involved, in addition to pain, the condition is of great concern to doctors because nerve root compression may progress to permanent nerve damage and loss of functioning, if the cause of the nerve compression is not corrected. For this reason, lumbar radiculopathy which also includes symptoms such as numbness and weakness in the leg or foot is one of the most common reasons why doctors consider back surgery to correct the condition.
Location and Labeling of the Lumbar Spine Nerve Roots: The lumbar spine includes the last five vertebrae that aren't naturally fused to one another following adulthood. The vertebral bones in the lumbar spine are labeled L1-L5, with L1 being the highest spinal bone in this section. The nerve root is named for the upper segment that it runs between. For example, the L2 nerve root is the nerve root at the L2-L3 segment.
The nerve root, which becomes the nerve and its thousands of nerve branches, may become compressed, irritated, or injured in any location once it leaves the spinal cord. That being said, the nerve is usually the most vulnerable to irritation where it runs over a weak spot in the disc space. When the disc that is closest to this disc space herniates, the nerve behind it may be affected, causing lower back pain, leg pain, sciatica, and lumbar radiculopathy.
Lumbar Nerves Associated with Radiculopathy and Sciatica: Though we also fancy ourselves as unique individuals, the map of our nervous system is actually identical across all people. This means that we all share the same number of spinal nerves, and they all travel to exactly the same spots in the body once they leave the spine. Each of these nerve roots supplies specific sections of the body, which enable us to have sensation, motor control, reflexes, and our bodily functions.
Doctors may use this information and understanding of the mapping of the nervous system to predict which nerves in the lumbar spine are compressed, based on the patient's signs and symptoms. When patients present with lumbar radiculopathy in the front and lateral side (the side away from the midline of the body), it is likely that the S1 or L5 nerve roots are compressed irritated. Signs and symptoms of lumbar radiculopathy in the calf and heel of the foot indicate nerve compression at L4.