Radiculopathy Health Article

Definition

Radiculopathy refers to disease of the spinal nerve roots (from the Latin radix for root). Radiculopathy produces pain, numbness, or weakness radiating from the spine.

Description

At the joints between the vertebrae, sensory nerves (nerves conducting sensory information toward the central nervous system) and motor nerves (nerves conducting commands to muscles away from the central nervous system) connect to the spinal cord. Each spinal nerve divides or fans out just before merging with the spinal cord. These smaller, separate nerve bundles are termed the roots of the nerve because they are reminiscent of the way the roots of a plant divide in the ground.

Damage to the spinal nerve roots can lead to pain, numbness, weakness, and paresthesia (abnormal sensations in the absence of stimuli) in the limbs or trunk. Pain may be felt in a region corresponding to a dermatome, an area of skin innervated by the sensory fibers of a given spinal nerve or a dynatome, an area in which pain is felt when a given spinal nerve is irritated. Dynatomes and dermatomes may overlap, but do not necessarily coincide.

Radiculopathies are categorized according to which part of the spinal cord is affected. Thus, there are cervical (neck), thoracic (middle back), and lumbar (lower back) radiculopathies. Lumbar radiculopathy is also known a sciatica. Radiculopathies may be further categorized by what vertebrae they are associated with. For example, radiculopathy of the nerve roots at the level of the seventh cervical vertebra is termed C7 radiculopathy; at the level of the fifth cervical vertebra, C5 radiculopathy; at the level of the first thoracic vertebra, T1 radiculopathy; and so on.

Radiculopathy is to be distinguished from myelopathy, which involves pathological changes in or functional problems with the spinal cord itself rather than the nerve roots. Sometimes, radiculopathy is also distinguished from radiculitis, the latter being defined as irritation (hence the "itis" suffix) of a nerve root that causes pain in the dermatome or dynatome corresponding to that nerve. Radiculopathy, on the other hand, denotes spinal nerve dysfunction (not just irritation) presenting with pain, altered reflex, weakness, and nerve-conduction abnormalities. Pain may not be present with radiculopathy, but is always present with radiculitis.

Demographics

Millions of persons experience some form of radiculopathy at some point in their lives. Because many of the causes of radiculopathy are long-term diseases (e.g., ankylosing spondylosis, diabetes) or diseases that tend to affect the elderly (e.g., arthritis), radiculopathy occurs more often in the middle-aged and elderly than in the young. However, injuries due to sports, heavy lifting, or bad posture affect the young as well. Cervical disc herniation with radiculopathy (mostly involving the C4 to C5 levels) affects 5.5 per 100,000 adults every year, with the highest risk being for adults 35 to 55 years year old.

Causes and symptoms

Radiculopathy can be caused by any disease or injury process that compresses or otherwise injures the spinal nerve roots. Violent blows or falls, cancer, some infections such as flu and Lyme disease, diseases that lead to degeneration of the vertebrae and/or intervertrebral discs (osteoarthritis), slipped or herniated discs, scoliosis, and other factors can cause radiculopathy. For example, extreme backward bending of the neck can trigger cervical radiculopathy. This has given rise to a recently-recognized category of radiculopathy termed "salon sink radiculopathy," so-called because salon patrons are asked to tip their heads sharply backward into sinks for shampooing. Spondylosis (immobilization and growing-together of one or more vertebral joints, often due to osteoarthritis) can deform the structures of bone, cartilage, and ligament through which spinal nerves must pass, leading to cervical and lumbar radiculopathy. Thoracic and lumbar radiculopathies are a common result of diabetes, which can impair blood flow to the spinal nerve roots.