Spinal Cord Injury

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Spinal Cord Injury

Definition

Spinal cord injury is damage to the spinal cord that causes loss of sensation and motor control.

Description

Approximately 11,000 new spinal cord injuries (SCIs) occur each year in the United States. About 200,000 people are currently affected. Spinal cord injuries can happen to anyone at any time of life. The typical patient, however, is a man between the ages of 19 and 26, injured in a motor vehicle accident (about 35% of all SCIs), a fall (20%), an act of violence (15%), most often related to firearms use or a sporting accident (14%). According to the Centers for Disease Control, violence-related SCIs have been increasing steadily since 1980, and in 2001, violence was associated with 30% of all SCI cases.

Most SCI patients are white, but the nonwhite fraction of SCI patients is larger than the nonwhite fraction of the general population. In fact, the SCI rate among blacks, who are at higher risk for SCI than whites, has been rising in recent years. Alcohol or other drug abuse plays an important role in a large percentage of all spinal cord injuries. Six percent of people who receive injuries to the lumbar spine die within a year, and 40% of people who sustain the more frequent higher, or rostral injuries, also die within a year.

Short-term costs for hospitalization, equipment, and home modifications are approximately $140,000 for an SCI patient capable of independent living. Lifetime costs may exceed one million dollars. Costs may be three to four times higher for the SCI patient who needs long-term institutional care. Overall costs to the American economy in direct payments and lost productivity are more than $10 billion per year.

Causes and symptoms

Causes

The spinal cord descends from the brain down the back through the spinal canal that lies within the bony spinal column. The spinal cord is composed of neurons and axons (nerve cells). The neurons carry sensory data from the areas outside the spinal cord (periphery) to the brain, and convey motor commands from brain to periphery. Peripheral neurons are bundled together to comprise the 31 pairs of peripheral nerve roots. The peripheral nerve roots enter and exit the spinal cord by passing through the spaces between the stacked vertebrae (the neural foramen). Each pair of nerves is named for the vertebra from which it exits. These are known as:

C1-8. These nerves enter from the seven cervical or neck vertebrae.
T1-12. These nerves enter from the thoracic or chest vertebrae.
L1-5. These nerves enter from the lumbar vertebrae of the lower back.
S1-5. These nerves enter through the sacral, or pelvic vertebrae.
Coccygeal. These nerves enter through the coccyx, or tailbone.

Peripheral nerves carry motor commands to the muscles and internal organs, and transmit sensations from these areas and from the body's surface. (Sensory data from the head, including sight, sound, smell, and taste, do not pass through the spinal cord and are not affected by most SCIs. These nerves, called the cranial nerves, pass through the brain stem.) Damage to the spinal cord interrupts these signals. The interruption damages motor functions that enable the muscles to move, sensory functions (e.g., feeling heat and cold), and autonomic functions (e.g., urination, sexual function, sweating, and blood pressure ).

Spinal cord injuries most often occur where the spine is most flexible, in the regions of C5-C7 of the neck, and T10-L2 at the base of the rib cage.

Several physically distinct types of damage are recognized. Sudden and violent jolts to nearby tissues can jar the cord. This jarring causes a transient neurological deficit, known as temporary spinal concussion. Concussion symptoms usually disappear completely within several hours of injury. A spinal contusion, or bruise, is bleeding within the spinal column. The pressure from the excess fluid may kill spinal cord neurons. Spinal compression is caused by an object, such as a tumor, pressing on the cord. Lacerations, or tears, cause direct damage to cord neurons. Lacerations may be caused by bone fragments or missiles, such as bullets. Spinal transection describes the complete severing of the cord. Most spinal cord injuries involve two or more of these types of damage.

Symptoms

PARALYSIS AND LOSS OF SENSATION. The extent to which movement and sensation are damaged depends on the level of the spinal cord injury. Nerves leaving the spinal cord at different levels control sensation and movement in different parts of the body. The distribution is roughly as follows:

C1-C4: head and neck
C3-C5: diaphragm (chest and breathing)
C5-T1: shoulders, arms and hands
T2-T12: chest and abdomen (excluding internal organs)
L1-L4: abdomen (excluding internal organs), buttocks, genitals, and upper legs
L4-S1: legs
S2-S4: genitals and muscles of the perineum

Damage below T1, which lies at the top of the rib cage, causes paralysis and loss of sensation in the legs and trunk below the injury. Injury at this level usually does no damage to the arms and hands. Paralysis of the legs is called paraplegia. Damage above T1 involves the arms as well as the legs. Paralysis of all four limbs is called quadriplegia.

Cervical, or neck injuries, not only cause quadriplegia, but also may cause difficulty in breathing. Damage in the lower part of the neck may leave enough diaphragm control to allow unassisted breathing. Patients with damage at C3 or above, just below the base of the skull, require mechanical assistance from a ventilator or a diaphragmatic nerve stimulation to breathe.

Symptoms also depend on the extent of the SCI. A completely severed cord causes paralysis and loss of sensation below the wound. If the cord is only partially severed, some function will remain below the injury. Damage limited to the front portion of the cord causes paralysis and loss of sensations of pain and temperature. Other sensation may be preserved. Damage to the center of the cord may spare the legs, but paralyze the arms. Damage to the right or left half causes loss of position sense, paralysis on the side of the injury, and loss of pain and temperature sensation on the opposite side.

AUTONOMIC DYSREFLEXIA. Body organs that self-regulate, such as the heart, gastrointestinal tract, and glands, are controlled by autonomic nerves. Autonomic nerves emerge from three different places: above the spinal column, in the lower back from vertebrae T1-L4, and from the lowest regions of the sacrum at the base of the spine. In general, these three groups of autonomic nerves operate in balance. Spinal cord injury can disrupt this balance, a condition called autonomic dysreflexia or autonomic hyperreflexia. Patients with injuries at T6 or above are at greatest risk.

SPASTICITY AND CONTRACTURE. A paralyzed limb is incapable of active movement, but the muscle still has tone, a constant low level of contraction. Normal muscle tone requires communication between the muscle and the brain. Spinal cord injury prevents the brain from telling the muscle to relax. The result is prolonged muscle contraction or spasticity. Since the muscles that extend and those that bend a joint are not usually equal in strength, the involved joint is bent, often severely. This constant pressure causes deformity. As the muscle remains in the shortened position over several weeks or months, the tendons remodel and cause permanent muscle shortening or contracture. When muscles have permanently shortened, the inner surfaces of joints, such as armpits or palms, cannot be cleaned and the skin breaks down in that area.

HETEROTOPIC OSSIFICATION. Heterotopic ossification is an abnormal deposit of bone in muscles and tendons that may occur after injury. It is most common in the hips and knees. Initially heterotopic ossification causes localized swelling, warmth, redness, and stiffness of the muscle. It usually begins one to four months after the injury and is rare after one year.

In autonomic dysreflexia, irritation of the skin, bowel, or bladder causes a highly exaggerated response from autonomic nerves. This response is caused by the uncontrolled release of norepinephrine, a hormone similar to adrenaline. Uncontrolled release of norepinephrine causes a rapid rise in blood pressure and a slowing of the heart rate. These symptoms are accompanied by throbbing headache, nausea, anxiety, sweating, and goose bumps below the level of the injury. The elevated blood pressure can rapidly cause loss of consciousness, seizures, cerebral hemorrhage, and death. Autonomic dysreflexia is most often caused by an over-full bladder or bladder infection, impaction or hard, impassable fecal mass in the bowel, or skin irritation from tight clothing, sunburn, or other irritant. Inability to sense these irritants before the autonomic reaction begins is a major cause of dysreflexia.

LOSS OF BLADDER AND BOWEL CONTROL. Bladder and bowel control require both motor nerves and the autonomic nervous system (ANS). Both of these systems may be damaged by SCI. When the ANS triggers an urge to urinate or defecate, continence is maintained by contracting the anal or urethral sphincter, respectively. The sphincter is a ring of muscle that contracts to close off a passage or opening in the body. When the neural connections to these muscles are severed, conscious control is lost. In addition, loss of feeling may prevent sensations of fullness from reaching the brain. To compensate, the patient may help empty the bowel or bladder by using physical maneuvers that stimulate autonomic contractions before they would otherwise begin. The patient may not, however, be able to relax the sphincters. If the sphincters cannot be relaxed, the patient will retain urine or feces.

Retention of urine may cause muscular changes in the bladder and urethral sphincter that make the problem worse. Urinary tract infection is common. Retention of feces can cause impaction. Symptoms of impaction include loss of appetite and nausea. Untreated impaction may cause perforation of the large intestine and sepsis (rapid overwhelming infection).

Complications

DEEP VENOUS THROMBOSIS. Blood does not flow normally through a paralyzed limb that is inactive for long periods. The blood pools in the deep veins and forms clots, a condition known as deep vein thrombosis. A clot, or thrombus, can break free and lodge in smaller arteries in the brain (causing a stroke), or in the lungs (causing pulmonary embolism).

DECUBITUS ULCERS (PRESSURE ULCERS). Inability to move may also lead to decubitus ulcers (pressure ulcers or bedsores). Decubitus ulcers form where skin remains in contact with a bed or chair for a long time. The most common sites of pressure ulcers are the buttocks, hips, and heels. Decubitus ulcers can cause sepsis (infection) and may seriously jeopardize recovery.

Diagnosis

The location and extent of SCI is determined by obtaining a history, performing a physical examination, and ordering appropriate imaging studies. Imaging studies usually include a combination of computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and traditional x rays. Computed tomography or MRI scans may be enhanced with an injected contrast dye. These diagnostic imaging studies are explained to patients by nurses and radiologic technicians. The studies are usually performed by these technicians, and are read, or interpreted, by a radiologist and/or a neuroradiologist.

Treatment

Acute care of SCI

Onlookers should not move a person who may have sustained SCI. Emergency medical personnel are best equipped to transport the injured patient. Treatment of SCI begins with immobilization. This strategy prevents partial injuries of the cord from severing it completely. Since the early 1980s, the use of splints to completely immobilize suspected SCI at the scene of the injury has helped reduce the severity of spinal cord injuries. Intravenous methylprednisolone, a steroidal anti-inflammatory drug, is given during the first 24 hours to reduce inflammation and limit tissue destruction.

Restoration of function and mobility

Rehabilitation after SCI seeks to prevent complications, promote recovery, and make the most of remaining function. Rehabilitation is a complex and long-term process; it requires a team of professionals, including a neurologist, physiatrist (or rehabilitation specialist), physical therapist, and occupational therapist. Other specialists who may be needed include a respiratory therapist, vocational rehabilitation counselor, social worker, speech-language pathologist, nutritionist, special education teacher, recreation therapist, and clinical psychologist. Support groups provide a critical source of information, advice, and support for SCI patients and their families. While the possibility of using functional electrical stimulation (FES) for ambulation (outside of the laboratory) remains distant, the use of FES to deal with other aspects of SCI (such as loss of grasp capabilities in quadriplegia) is actually more advanced and more likely to be in common use in the forseeable future.

Instruction in activities of daily living

Physical therapy focuses on mobility to maintain range of motion of affected limbs and reduce contracture and deformity. Additionally, it helps to compensate for lost skills by using those muscles that are still functional, and helps to increase any residual strength and control in affected muscles. Adaptive equipment such as braces, canes, or wheelchairs can be suggested by a physical therapist.

The goal of occupational therapy is to restore the ability to perform the activities of daily living, such as eating and grooming, with tools and new techniques. Modifications of the home and workplace to accommodate and address the individual impairment are also addressed by the occupational therapist.

Treatment of sexual dysfunction

Men who have sustained SCI may be unable to achieve an erection or ejaculate. Sperm formation may be abnormal and fertility may be compromised. Fertility and the ability to achieve orgasm are less impaired for women. Women may still be able to become pregnant and deliver vaginally.

Prevention of complications

DECUBITUS ULCERS (PRESSURE ULCERS). Turning the patient in bed at least every two hours prevents the formation of decubitus ulcers. The patient should be turned more frequently when redness begins to develop in sensitive areas. Special mattresses and chair cushions can distribute weight more evenly to reduce pressure. Skin should be carefully attended to by nurses and other caregivers in order to maintain skin integrity and prevent ulcers from developing. Electrical stimulation is sometimes used to promote muscle movement to prevent decubitus ulcers.

SPASTICITY AND CONTRACTURE. Range of motion (ROM) exercises help to prevent contracture. Chemicals can be used to prevent contractures from becoming fixed when ROM exercise is inadequate. Phenol or alcohol can be injected into the nerve, or botulinum toxin can be injected directly into the muscle. Botulinum toxin is associated with fewer complications, but it is more expensive than phenol and alcohol. Contractures can be released by cutting the shortened tendon or transferring it surgically to a different site on the bone, where deformity will be lessened by its pull. Such tendon transfers may also be used to increase strength in partially functional extremities.

DEEP VENOUS THROMBOSIS. Deep venous thrombosis may be prevented by using passive ROM exercises, sequential compression stockings, intermittent pneumatic compression devices, and kinetic (movement) therapies. Heparin and aspirin may also be administered to prevent deep venous thrombosis.

HETEROTOPIC OSSIFICATION. Etidronate disodium (Didronel), a drug that regulates the body's use of calcium, is used to prevent heterotopic ossification. Treatment begins three weeks after the injury and continues for 12 weeks. Surgical removal of ossified tissue is possible.

AUTONOMIC DYSREFLEXIA. Bowel and bladder care and attention to potential irritants prevent autonomic dysreflexia. It is treated by prompt removal of the irritant. Drugs to lower blood pressure are used when necessary. Patients and friends and families of the patient should be educated about the symptoms and treatment of dysreflexia, because immediate intervention is usually necessary.

LOSS OF BLADDER AND BOWEL CONTROL. Normal bowel function is promoted through adequate fluid intake and a diet rich in fiber. Evacuation is stimulated by deliberately increasing the abdominal pressure, either voluntarily or by using an abdominal binder.

Bladder care involves continual or intermittent catheterization. The full bladder may be detected by feeling its bulge against the abdominal wall. Urinary tract infection is a significant complication of catheterization and requires frequent monitoring.

SEXUAL DYSFUNCTION. Counseling can help patients to adjust to changes in sexual function after SCI. Erection may be enhanced through the same means used to treat erectile dysfunction in the general population.

Prognosis

The prognosis for SCI depends on the site and extent of injury. Injuries of the neck above C4 with significant involvement of the diaphragm hold the gravest prognosis. Respiratory infection is one of the leading causes of death in long-term SCI. Overall, 85% of SCI patients who survive the first 24 hours are alive ten years after their injuries. Recovery of function is impossible to predict. Partial recovery is more likely after an incomplete wound than after the spinal cord has been completely severed.

Health care team roles

Initial medical management, including immobilization and transport of SCI patients, is usually provided by emergency medical personnel. Upon arrival, the physicians and nurses in the hospital emergency department assess the nature and extent of the injury. Imaging studies are performed by radiologic technicians and interpreted by radiologists and neuroradiologists. Consultation with a neurosurgeon determines whether surgical intervention will be beneficial in treating the injury.

Following emergency treatment, assessment and completion of the diagnostic work-up, critical care vigilant monitoring of SCI patients is provided by the nurses. The aim of monitoring is to identify the decreased cardiac output that may result from sympathetic nerve blockade; excessive autonomic nerve responses (i.e., distended bladder or bowel); problems associated with breathing; and the risk of aspiration.

Nurses, social workers, physical and occupational therapists, pastoral counselors, and other medical and mental health professionals may be called upon to help patients and families manage their emotional responses to the injury. Feelings of anxiety, anger, and denial may be experienced by hopeless patients and families.

Patient education

Patient education is an essential part of the rehabilitation process. Every member of the treatment team is involved in patient education. Patients and families are taught by nurses to recognize symptoms requiring immediate medical attention, and to provide selected care (e.g., a bowel program to prevent impaction). They may be instructed by physical and occupational therapists to use adaptive devices and equipment. Education may help to reduce feelings of powerlessness and hopelessness, and can assist in the creation of realistic expectations about recovery.

Many SCI patients also benefit from participation in peer support groups. They are enabled by the groups to meet others with comparable conditions, thereby reducing feelings of isolation, and allowing them to share experience-tested coping strategies.

KEY TERMS

Autonomic nervous system— The part of the nervous system that controls involuntary functions such as sweating and blood pressure.

Botulinum toxin— Any of a group of potent bacterial toxins or poisons produced by different strains of the bacterium Clostridium botulinum.

Computed tomography (CT)— An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures.

Magnetic resonance imaging (MRI)— An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Motor— Of or pertaining to motion, the body apparatus involved in movement, or the brain functions that direct purposeful activity.

Motor nerve— Motor or efferent nerve cells carry impulses from the brain to muscle or organ tissue.

Peripheral nervous system— The part of the nervous system that is outside the brain and spinal cord. Sensory, motor, and autonomic nerves are included.

Postural drainage— The use of positioning to drain secretions from the bronchial tubes and lungs into the trachea or windpipe.

Range of motion (ROM)— The range of motion of a joint from full extension to full flexion (bending) measured in degrees like a circle.

Sensory nerves— Sensory or afferent nerves carry impulses of sensation from the periphery or outward parts of the body to the brain. Sensations include feelings, impressions, and awareness of the state of the body.

Voluntary— An action or thought undertaken or controlled by a person's free will or choice.

Prevention

Risk of spinal cord injury can be reduced through prevention of the accidents that lead to it. Chances of injury from automobile accidents, the major cause of SCIs, can be significantly reduced by driving at safe speeds, avoiding alcohol while driving, not talking on mobile phones while driving, and using seat belts.

Paralysis and loss of sensation

Some limited mobility and sensation may be recovered, but the extent and speed of recovery cannot be predicted with any accuracy. Experimental electrical stimulation has been demonstrated to allow some control of muscle contraction in paraplegia. This experimental technique offers the possibility of unaided walking. Further development of current control systems will be needed before useful movement is possible outside the laboratory.

A pulmonologist, or respiratory therapist, can promote airway hygiene through instruction in assisted coughing techniques and postural drainage. Ventilators, facial or nasal masks, and tracheostomy equipment, where necessary, can also be prescribed by the respiratory professional. He or she can provide instruction in their use, as well.