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.
Anatomy of the Spinal Cord
The spinal cord extends caudally from the medulla at the foramen magnum and terminates at the upper lumbar vertebrae, usually between L1 and L2, where it forms the conus medullaris. In the lumbosacral region, nerve roots from lower cord segments descend within the spinal column in a nearly vertical sheaf, forming the cauda equina.
The white matter at the cord’s periphery contains ascending and descending tracts of myelinated sensory and motor nerve fibers. The central H-shaped gray matter is composed of cell bodies and nonmyelinated fibers (see figure Spinal nerve Spinal nerve "Numbness" can be used by patients to describe various symptoms, including loss of sensation, abnormal sensations, and weakness or paralysis. However, numbness is actually loss of sensation... read more ). The anterior (ventral) horns of the “H” contain lower motor neurons, which receive impulses from the motor cortex via the descending corticospinal tracts and, at the local level, from internuncial neurons and afferent fibers from muscle spindles. The axons of the lower motor neurons are the efferent fibers of the spinal nerves. The posterior (dorsal) horns contain sensory fibers that originate in cell bodies in the dorsal root ganglia. The gray matter also contains many internuncial neurons that carry motor, sensory, or reflex impulses from dorsal to ventral nerve roots, from one side of the cord to the other, or from one level of the cord to another.
The spinothalamic tract transmits pain and temperature sensation contralaterally in the spinal cord; most other tracts transmit information ipsilaterally. The cord is divided into functional segments (levels) corresponding approximately to the attachments of the 31 pairs of spinal nerve roots.
Etiology of Spinal Cord Disorders
Spinal cord disorders usually result from conditions extrinsic to the cord, such as the following:
Less commonly, disorders are intrinsic to the cord. Intrinsic disorders include spinal cord infarction Spinal Cord Infarction Spinal cord infarction usually results from ischemia originating in an extravertebral artery. Symptoms include sudden and severe back pain, followed immediately by rapidly progressive bilateral... read more , hemorrhage, transverse myelitis Acute Transverse Myelitis Acute transverse myelitis is acute inflammation of gray and white matter in one or more adjacent spinal cord segments, usually thoracic. Causes include multiple sclerosis, neuromyelitis optica... read more , HIV infection, poliovirus infection Poliomyelitis Poliomyelitis is an acute infection caused by a poliovirus (an enterovirus). Manifestations include a nonspecific minor illness (abortive poliomyelitis), sometimes aseptic meningitis without... read more , West Nile virus infection, syphilis (which can cause tabes dorsalis Late or tertiary 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 ), trauma Spinal Trauma Trauma to the spine may cause injuries involving the spinal cord, vertebrae, or both. Occasionally, the spinal nerves are affected. The anatomy of the spinal column is reviewed elsewhere. Spinal... read more , vitamin B12 deficiency Vitamin B12 Deficiency Dietary vitamin B12 deficiency usually results from inadequate absorption, but deficiency can develop in vegans who do not take vitamin supplements. Deficiency causes megaloblastic anemia, damage... read more (which causes subacute combined degeneration Subacute Combined Degeneration Subacute combined degeneration refers to degenerative changes in the nervous system due to vitamin B12 deficiency; the degenerative changes affect mostly brain and spinal cord white matter.... read more ), decompression sickness Decompression Sickness Decompression sickness occurs when rapid pressure reduction (eg, during ascent from a dive, exit from a caisson or hyperbaric chamber, or ascent to altitude) causes gas previously dissolved... read more , lightning injury Lightning Injuries Lightning injuries include cardiac arrest, loss of consciousness, and temporary or permanent neurologic deficits; serious burns and internal tissue injury are rare. Diagnosis is clinical; evaluation... read more (which can cause keraunoparalysis Symptoms and Signs Lightning injuries include cardiac arrest, loss of consciousness, and temporary or permanent neurologic deficits; serious burns and internal tissue injury are rare. Diagnosis is clinical; evaluation... read more [transient paralysis and sensory deficits with ischemia]), radiation therapy (which can cause myelopathy), syrinx Syrinx of the Spinal Cord or Brain Stem A syrinx is a fluid-filled cavity within the spinal cord (syringomyelia) or brain stem (syringobulbia). Predisposing factors include craniocervical junction abnormalities, previous spinal cord... read more , and spinal cord tumor 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 . Arteriovenous malformations Spinal Cord Arteriovenous Malformations (AVMs) Arteriovenous malformations (AVMs) in or around the spinal cord can cause cord compression, ischemia, parenchymal hemorrhage, subarachnoid hemorrhage, or a combination. Symptoms may include... read more may be extrinsic or intrinsic. Copper deficiency Copper Deficiency Copper is a component of many body proteins; almost all of the body’s copper is bound to copper proteins. Copper deficiency may be acquired or inherited. (See also Overview of Mineral Deficiency... read more may result in myelopathy similar to that caused by vitamin B12 deficiency.
Symptoms and Signs of Spinal Cord Disorders
Neurologic dysfunction due to spinal cord disorders occurs at the involved spinal cord segment (see table Motor and Reflex Effects of Spinal Cord Dysfunction by Segmental Level Motor and Reflex Effects of Spinal Cord Dysfunction by Segmental Level 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 ) and at all segments below it. The exception is the central cord syndrome (see table Spinal Cord Syndromes Spinal Cord Syndromes 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 ), which may spare segments below.
Spinal cord disorders cause various patterns of deficits depending on which nerve tracts within the cord or which spinal roots outside the cord are damaged. Disorders affecting spinal nerves, but not directly affecting the cord, cause sensory or motor abnormalities or both only in the areas supplied by the affected spinal nerves.
Spinal cord dysfunction causes
Loss of sensation
Autonomic dysfunction (eg, bowel, bladder, and erectile dysfunction; loss of sweating)
Dysfunction may be partial (incomplete). Autonomic and reflex abnormalities are usually the most objective signs of cord dysfunction; sensory abnormalities are the least objective.
Corticospinal tract lesions cause upper motor neuron dysfunction. Acute, severe lesions (eg, infarction, traumatic lesions) cause spinal shock with flaccid paresis (decreased muscle tone, hyporeflexia, and no extensor plantar responses). After days or weeks, upper motor neuron dysfunction evolves into spastic paresis (increased muscle tone, hyperreflexia, and clonus). Extensor plantar responses and autonomic dysfunction are present. Flaccid paresis that lasts more than a few weeks suggests lower motor neuron dysfunction (eg, due to Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is an acute, usually rapidly progressive but self-limited inflammatory polyneuropathy characterized by muscular weakness and mild distal sensory loss. Cause is thought... read more ).
Specific cord syndromes include the following (see table Spinal Cord Syndromes Spinal Cord Syndromes 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 ):
Central cord syndrome
Anterior cord syndrome
Conus medullaris syndrome
Cauda equina syndrome Cauda Equina Syndrome Cauda equina syndrome occurs when the nerve roots at the caudal end of the cord are compressed or damaged, disrupting motor and sensory pathways to the lower extremities and bladder. (See also... read more , which involves damage to nerve roots at the caudal end of the cord, is not a spinal cord syndrome. However, it mimics conus medullaris syndrome, causing leg paresis and sensory loss involving the affected nerve roots (often in the saddle area), as well as bladder, bowel, and pudendal dysfunction.
Diagnosis of Spinal Cord Disorders
Neurologic deficits at segmental levels suggest a spinal cord disorder. Similar deficits, especially if unilateral, may result from nerve root or peripheral nerve disorders, which can usually be differentiated clinically. Level and pattern of spinal cord dysfunction help determine presence and location of a spinal cord lesion but not always type of lesion.
MRI is the most accurate imaging test for spinal cord disorders; MRI shows spinal cord parenchyma, soft-tissue lesions (eg, abscesses, hematomas, tumors, abnormalities involving intervertebral disks), and bone lesions (eg, erosion, severe hypertrophic changes, collapse, fracture, subluxation, tumors).
Myelography with a radiopaque agent followed by CT is used less often. It is not as accurate as MRI and is more invasive but may be more readily available and may be needed for patients who are unable to undergo MRI (eg, due to permanent pacemaker).
Plain x-rays may help detect bone lesions.
Treatment of Spinal Cord Disorders
Treatment of the cause when possible
Prevention of complications
Physical and occupational therapy
If symptoms of a spinal cord disorder (eg, paralysis loss of sensation) occur suddenly, emergency treatment is required.
If possible, the cause is treated or corrected.
Measures to prevent problems due to bed rest Bed Rest Effects A hospital may provide emergency medical care, diagnostic testing, intensive treatment, or surgery, which may or may not require admission. Older patients use hospitals more than younger patients... read more are essential if patients are paralyzed or confined to bed.
Extensive loss of body functions can be devastating, causing depression and loss of self-esteem. Formal counseling can help patients cope with loss of function and prepare them for rehabilitation.
Rehabilitation Spinal cord injury Rehabilitation aims to facilitate recovery from loss of function. (See also Overview of Rehabilitation.) Patients with arthritis can benefit from activities and exercises to increase joint range... read more is best provided by an interdisciplinary team (nurses, physical therapist Physical Therapy (PT) Physical therapy aims to improve joint and muscle function (eg, range of motion, strength) and thus improve the patient’s ability to stand, balance, walk, and climb stairs. For example, physical... read more , occupational therapist Occupational Therapy (OT) Occupational therapy (OT) focuses on self-care activities and improvement of fine motor coordination of muscles and joints, particularly in the upper extremities. Unlike physical therapy, which... read more , social worker, nutritionist, psychologist, counselor); the team also includes the patient and family members.