Causes / typical injury mechanism: Lumbar radiculopathy (LR) results from irritation of a nerve that originates from the lumbar spine, including the L1-L5 nerve roots and the S1-S3 upper sacral nerve roots. The most common cause of LR is degenerative spondyloarthropathy, which includes disk herniation, facet hypertrophy, and spondylolisthesis. Inflammatory processes such as malignancies and infections may lead to similar symptoms.

The source of LR is irritation or compression of a particular nerve, which can occur in multiple places including the thecal sac, the lateral recess, and the neural foramen. LR is often referred to as sciatica when the neuropathic findings match the sciatic nerve roots' dermatomal pattern of L4-S1.

Classic history and presentation: Patients commonly present with back pain described as radiating down the leg with a sharp, electric-like, or burning sensation. A recent incident of trauma or heavy lifting and twisting of the spine with acute onset of symptoms can suggest acute disk herniation leading to radiculopathy. There may be associated numbness and weakness in the affected leg depending on the degree of nerve compression or irritation.

Prevalence: Up to 80% of adults will experience low back pain at some point in their lifetime, with prevalence of LR of 3%-5%. About 85% of LR cases are due to disk herniation at the L4-L5 or L5-S1 level.

• Age – Symptoms often begin in midlife, with peak incidence for men at about 45 years and for women at 64 years.
• Sex / gender – Men have a slightly higher predominance than women. However, women in careers that have high physical demands have a similar incidence to men.

Risk factors: The main risk factors for LR are those that lead to degenerative lumbar disk disease. These include older age, obesity, taller height, smoking, and occupational factors, including jobs that involve frequent lifting or driving. In addition, patients with osteoporosis are predisposed to vertebral body compression fractures and have increased risk of LR.

Pathophysiology: Age-related degenerative changes of the lumbar spinal column lead to
disk herniation. A herniated disk is a protrusion of the nucleus pulposus through the weakened annulus fibrosus between the vertebrae, which causes nerve root compression, irritation, and pain. Lumbar disk herniation most commonly occurs at the L4-L5 and L5-S1 levels, as most movement of the spine occurs in this region.

Related topic: axial low back pain without radiculopathy