Herniations occur most commonly through a posterolateral defect, but midline herniations may occur. Resulting compression of the spinal nerve root causes inflammation and pain, usually along the anatomic course of the nerve. In the lumbar spine, this most often occurs at the L4 and L5 disc levels, causing pressure on the corresponding L5 and S1 nerve roots. As a result of both mechanical and biochemical changes around the nerve root, the injured worker will experience pain, paresthesia, and possibly weakness in the leg or legs usually below the knee. The rare herniations at the L1, L2 and L3 levels are usually associated with pain, paresthesia, and weakness above the knee. Back pain may or may not be a presenting complaint with any herniated lumbar disc.
Back pain is usually the first symptom and may or may not abate as the pain and paresthesias begin to radiate down the leg. The leg pain is often described as a sharp, shooting pain that radiates along the anatomic course of the nerve from proximal to distal. The onset may be sudden or insidious. The injured worker often has difficulty getting up from sitting or supine positions and commonly leans or lists to one side or the other. Motion of the spine is limited due to pain and muscle spasm. The neurological examination may be normal if the compressed nerve is still functional, or it may yield objective evidence of impaired nerve function (e.g. atrophy, weakness, sensory alteration or diminished reflex) depending upon the nerve root affected. Signs of nerve root tension (e.g. positive straight leg raising) may also be present.
When the L4 disc herniates, it usually causes pressure on the L5 nerve root resulting in weakness of the great toe extensor or other dorsiflexor muscles of the foot and sensory loss along the medial aspect of the foot to the great toe, but it is usually not associated with reflex abnormality. When the L5 disc herniates, it usually causes pressure on the S1 nerve root, resulting in a sensory deficit in the posterior calf area and lateral aspect of the foot in addition to a diminished Achilles' reflex and occasional weakness of the plantar flexors of the foot.
The value of periods of bed rest has not been demonstrated. Complete bed rest for prolonged periods may be deleterious to the body and should be closely monitored. A significant number of injured workers will respond to a nonoperative treatment program for herniated lumbar disc. The physician should be aware that those injured workers who have marked, early limitation of straight leg raising and those injured workers who have symptoms or physical findings suggestive of cauda equina syndrome may need early surgery. Close monitoring is indicated in those settings.
W. Va. Code R. § 85-20-38