(See also Overview of Peripheral Nervous System Disorders Overview of Peripheral Nervous System Disorders The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves and spinal nerves from their origin to their end. The anterior... read more .)
Nerve root disorders (radiculopathies) are precipitated by acute or chronic pressure on a nerve root in adjacent to the spinal column (see figure Spinal nerve roots Spinal nerve roots Nerve root disorders result in segmental radicular deficits (eg, pain or paresthesias in a dermatomal distribution, weakness of muscles innervated by the root). Diagnosis may require neuroimaging... read more ).
Spinal nerve roots
Etiology of Nerve Root Disorders
The most common cause of radiculopathies is
Bone changes due to rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that primarily involves the joints. RA causes damage mediated by cytokines, chemokines, and metalloproteases. Characteristically... read more (RA) or osteoarthritis Osteoarthritis (OA) Osteoarthritis is a chronic arthropathy characterized by disruption and potential loss of joint cartilage along with other joint changes, including bone hypertrophy (osteophyte formation). Symptoms... read more , especially in the cervical and lumbar areas, may also compress isolated nerve roots.
Less commonly, carcinomatous meningitis causes patchy multiple root dysfunction. Rarely, spinal mass lesions (eg, epidural abscesses Spinal Epidural Abscess A spinal epidural abscess is an accumulation of pus in the epidural space that can mechanically compress the spinal cord. Diagnosis is by MRI or, if unavailable, myelography followed by CT.... read more and tumors Spinal Cord Tumors Spinal cord tumors may develop within the spinal cord parenchyma, directly destroying tissue, or outside the cord parenchyma, often compressing the cord or nerve roots. Symptoms can include... read more , spinal meningiomas Extramedullary tumors Spinal cord tumors may develop within the spinal cord parenchyma, directly destroying tissue, or outside the cord parenchyma, often compressing the cord or nerve roots. Symptoms can include... read more , neurofibromas Neurofibromatosis Neurofibromatosis refers to several related disorders that have overlapping clinical manifestations but that are now understood to have distinct genetic causes. It causes various types of benign... read more ) may manifest with radicular symptoms instead of the usual symptoms of spinal cord dysfunction Symptoms and Signs Spinal cord disorders can cause permanent severe neurologic disability. For some patients, such disability can be avoided or minimized if evaluation and treatment are rapid. The spinal cord... read more .
Diabetes Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more can cause a painful thoracic or extremity radiculopathy by causing ischemia of the nerve root.
Infectious disorders, such as those due to mycobacteria (eg, tuberculosis Tuberculosis (TB) Tuberculosis (TB) is a chronic, progressive mycobacterial infection, often with a period of latency following initial infection. TB most commonly affects the lungs. Symptoms include productive... read more [TB]), fungi (eg, histoplasmosis Histoplasmosis Histoplasmosis is a pulmonary and hematogenous disease caused by Histoplasma capsulatum; it is often chronic and usually follows an asymptomatic primary infection. Symptoms are those of pneumonia... read more ), or spirochetes (eg, Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by the spirochete Borrelia species. Early symptoms include an erythema migrans rash, which may be followed weeks to months later by neurologic... read more , syphilis Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential clinical, symptomatic stages separated by periods of asymptomatic latent infection. Common manifestations... read more ), sometimes affect nerve roots. Herpes zoster infection Herpes Zoster Herpes zoster is infection that results when varicella-zoster virus reactivates from its latent state in a posterior dorsal root ganglion. Symptoms usually begin with pain along the affected... read more usually causes a painful radiculopathy with dermatomal sensory loss and characteristic rash, but it may cause a motor radiculopathy with segmental weakness and reflex loss. Cytomegalovirus-induced polyradiculitis is a complication of AIDS.
Symptoms and Signs of Nerve Root Disorders
Radiculopathies tend to cause characteristic radicular syndromes of pain and segmental neurologic deficits based on the cord level of the affected root (see table Symptoms of Common Radiculopathies by Cord Level Symptoms of Common Radiculopathies by Cord Level Nerve root disorders result in segmental radicular deficits (eg, pain or paresthesias in a dermatomal distribution, weakness of muscles innervated by the root). Diagnosis may require neuroimaging... read more ). Muscles innervated by the affected motor root become weak and atrophy; they also may be flaccid with fasciculations. Sensory root involvement causes sensory impairment in a dermatomal distribution. Corresponding segmental deep tendon reflexes may be diminished or absent. Electric shock–like pains may radiate along the affected nerve root’s distribution.
Pain may be exacerbated by movements that transmit pressure to the nerve root through the subarachnoid space (eg, moving the spine, coughing, sneezing, doing the Valsalva maneuver).
Lesions of the cauda equina, which affect multiple lumbar and sacral roots, cause radicular symptoms in both legs and may impair sphincter and sexual function.
Findings indicating spinal cord compression Spinal Cord Compression Various lesions can compress the spinal cord, causing segmental sensory, motor, reflex, and sphincter deficits. Diagnosis is by MRI. Treatment is directed at relieving compression. (See also... read more include the following:
A sensory level (an abrupt change in sensation below a horizontal line across the spine)
Flaccid paraparesis or quadriparesis
Reflex abnormalities below the site of compression
Early-onset hyporeflexia followed later by hyperreflexia
Diagnosis of Nerve Root Disorders
Sometimes electrodiagnostic tests
Radicular symptoms require MRI or CT of the affected area. Myelography is needed only if MRI is contraindicated (eg, because of an implanted pacemaker or presence of other metal) and CT is inconclusive. The area imaged depends on symptoms and signs; if the level is unclear, electrodiagnostic tests should be done to localize the affected root, but they cannot identify the cause.
If imaging does not detect an anatomic abnormality, cerebrospinal fluid analysis is done to check for infectious or inflammatory causes, and fasting plasma glucose is measured to check for diabetes Diagnosis Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more .
Treatment of Nerve Root Disorders
Treatment of the cause and of pain
Surgery (as a last resort)
Specific causes of nerve root disorders are treated.
Acute pain requires appropriate analgesics (eg, acetaminophen, nonsteroidal anti-inflammatory drugs [NSAIDs], sometimes opioids). NSAIDs are particularly useful for disorders that involve inflammation. Muscle relaxants, sedatives, and topical treatments rarely provide additional benefit. If symptoms are not relieved with nonopioid analgesics, corticosteroids can be given systemically or as an epidural injection; however, analgesia tends to be modest and temporary. Methylprednisolone may be given, tapered over 6 days, starting with 24 mg orally once a day and decreased by 4 mg a day.
Management of chronic pain Treatment Chronic pain is pain that persists or recurs for > 3 months, persists > 1 month after resolution of an acute tissue injury, or accompanies a nonhealing lesion. Causes include chronic disorders... read more can be difficult; acetaminophen and NSAIDs are often only partly effective, and long-term use of NSAIDs has substantial risks. Opioids have a high risk of addiction. Tricyclic antidepressants and antiseizure drugs may be effective, as may physical therapy and consultation with a mental health practitioner. For a few patients, alternative medical treatments (eg, transdermal electrical nerve stimulation Electrical stimulation Treatment of pain and inflammation aims to facilitate movement and improve coordination of muscles and joints. Nondrug treatments include therapeutic exercise, heat, cold, electrical stimulation... read more , spinal manipulation Chiropractic In chiropractic (a manipulative and body-based practice), the relationship between the structure of the spine and other articulating surfaces and their interaction with the nervous system is... read more , acupuncture Acupuncture Acupuncture, a therapy within traditional Chinese medicine, is one of the most widely accepted components of integrative therapies in the western world. Specific points on the body are stimulated... read more , medicinal herbs Overview of Dietary Supplements Dietary supplements are the most commonly used of all integrative, complementary, and alternative therapies, primarily because they are widely available, relatively inexpensive, and can be bought... read more ) may be tried if all other treatments are ineffective.
If the pain is intractable or if progressive weakness or sphincteric dysfunction suggest spinal compression, surgical decompression may be necessary.
Suspect a nerve root disorder in patients who have segmental deficits such as sensory abnormalities in a dermatomal distribution (eg, pain, paresthesias) and/or motor abnormalities (eg, weakness, atrophy, fasciculations, hyporeflexia) at a nerve root level.
If patients have a sensory level, bilateral flaccid weakness, and/or sphincter dysfunction, suspect spinal cord compression.
If clinical findings suggest radiculopathy, do MRI or CT.
Use analgesics and sometimes corticosteroids for acute pain, and consider other drugs and other treatments, as well as analgesics, for chronic pain.
In patients with progressive weakness and sphincteric dysfunction, consider surgical decompression.