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Spinal Cord Injury

Spinal cord injury

Definition

Spinal cord injury (SCI) is damage to the spinal cord that results in a loss of function such as mobility or feeling. The spinal cord does not have to be severed in order for a loss of function to occur. In most SCI cases, the spinal cord is intact, but the damage to it results in loss of function.

Description

The spinal cord and the brain are the two components of the central nervous system (CNS). The spinal cord extends from the base of the brain, down the middle of the back, to the lower back, and it coordinates movement and sensation in the body. It contains nerve cells, supporting cells, and long nerve fibers (axons) that connect to the brain and carry signals downward from the brain along descending pathways and upward to the brain along ascending pathways. Axons are covered by sheaths of an insulating whitish substance called myelin, and the region in which they lie is accordingly called white matter. The nerve cells themselves, with long branches (dendrites) that receive signals from other nerve cells, make up the gray matter that lies in a butterfly-shaped region in the center of the spinal cord. Like the brain, the spinal cord is enclosed in three membranes (meninges). The innermost layer is called the pia mater, the middle layer is the arachnoid, and the dura mater is the tougher outer layer. The spinal cord consists of several segments along its length, with higher segments controlling movement and sensation in upper parts of the body and lower segments controlling the lower parts of the body. The segments in the neck (cervical region), referred to as C1 to C8, control signals to the neck, arms, and hands. Those in the thoracic or upper back region (T1 to T12) control signals to the torso and some parts of the arms. Those in the mid-back (upper lumbar region) just below the ribs (L1 to L5) control signals to the hips and legs. Finally, the sacral segments (S1 to S5) lie just below the lumbar segments in the mid-back and control signals to the groin, toes, and some parts of the legs.

The types of disability associated with SCI thus depend directly on the type and severity of the injury, the level of the cord at which the injury occurs, and the nerve fiber pathways that are damaged. Severe injury to the spinal cord causes paralysis and complete loss of sensation to the parts of the body controlled by the spinal cord segments below the point of injury. Spinal cord injuries also can lead to many complications, including pressure sores and increased susceptibility to respiratory diseases.

Demographics

According to the National Institute of Neurological Disorders and Stroke (NINDS), accidents and violence cause an estimated 10,000 spinal cord injuries each year, and more than 200,000 Americans live day-to-day with the disabling effects of SCI. The incidence of spinal cord injuries peaks among people in their early 20s, with a small increase in the elderly population due to falls and degenerative diseases of the spine. SCI is an uncommon source of morbidity and mortality in children.

Causes and symptoms

According to the National Spinal Cord Injury Association (NSCIA), spinal cord injuries are caused in the United States by motor vehicle accidents (44%), acts of violence (24%), falls (22%), sports (8%), and other causes (2%) such as abscesses, tumors, polio , spina bifida and Friedrich's Ataxia, a rare inherited disorder. For infants, motor vehicle crash is the leading cause of SCI. Falls rank highest for ages two to nine years and sports for the 10 to 14 age group. The most common injury level for the five to 13 age group is the high cervical spine (C1-C4).

SCI symptoms usually appear immediately after the injury. However, symptoms can develop slowly, if an infection or tumor is gradually increasing pressure on the spinal cord. General symptoms are as follows:

  • weakness, poor coordination or paralysis, particularly below the level of the injury
  • numbness , tingling, or loss of sensation
  • loss of bowel or bladder control
  • pain

When to call the doctor

Immediate medical attention is required if a parent suspects a child may have injured his or her neck or back, or if a child has poor coordination or paralysis in any part of the body. Spinal cord injury is not always obvious: numbness or paralysis may result immediately after SCI or later on as swelling gradually occurs in or around the spinal cord. In either case, the time between injury and treatment is critical and can significantly influence the extent of complications and the level of recovery. Any child who has experienced significant trauma to the head, back, or neck should be medically evaluated for the possibility of SCI.

Diagnosis

The possibility of SCI is usually suspected in anyone with significant trauma to the head and/or neck. Physicians accordingly assume that such patients have a spine fracture until proven otherwise.

Diagnosis is established with the help of x-rays of the spine that allow doctors to determine the extent of the damage. The following imaging tests are also used: CT scan (computed tomography ), MRI (magnetic resonance imaging ), and myelogram (x ray after injection of dye into the spinal canal).

Treatment

A person suspected of having a spinal cord injury should not be moved and treatment of SCI begins with immobilization , commonly achieved by enclosing the cervical spine in a rigid collar and use of rigid backboards. Paramedics and other rescue workers receive extensive training in immobilizing the spine. Immobilization prevents further injuries to the cord at the scene of the injury and has helped reduce worsening of any neurological SCI injury. At the time of injury, treatment is focused on stabilizing the spine and relieving cord compression. Prompt steroid drug injections (within eight hours of the injury) are also used to minimize cell damage and improve the chance of recovery.

Surgery cannot reverse damage to the spinal cord but is often needed to stabilize the spine to prevent future pain or deformity. It may involve fusing together vertebrae or inserting metal pins; or removing bone chips, bullets, or other foreign objects ; or draining fluid to relieve pressure. Long-term treatment of spinal cord injuries usually involves drug therapy, the use of neural prostheses, and rehabilitation. Complementary treatment includes nutrition management, psychological counseling, and careful monitoring by physicians.

Drug therapy

Effective drug therapy for spinal cord injury was demonstrated in 1990, when methylprednisolone, the first drug shown to improve recovery from spinal cord injury, was approved for standard use. Completely paralyzed patients given methylprednisolone recover an average of about 20 percent of their lost motor function, compared to only 8 percent recovery of function in untreated patients. Partially paralyzed patients recover an average of 75 percent of their function, compared to 59 percent in patients who do not receive the drug.

Neural prostheses

Neural prostheses are used to compensate for lost function resulting from SCI. These sophisticated electrical and mechanical devices connect with the nervous system to supplement or replace lost motor and sensory functions. Neural prostheses contain many intricate components, such as implanted stimulators, electrodes, leads and connectors, sensors, and programming systems. There are many technical considerations in selecting each component. The electronic components must be as small as possible. Biocompatibility between electrodes and body tissue is also required to prevent the patient from being harmed by contact with the device. One device, a neural prosthesis that allows rudimentary hand control, was approved by the United States Food and Drug Administration (FDA). Patients control the device using shoulder muscles. With training, most patients can open and close their hand in two different grasping movements and lock the grasp in place by moving their shoulder in different ways.

Rehabilitation

Rehabilitation techniques can greatly improve patients' health and quality of life by helping them learn to use their remaining abilities. They start by setting functional goals. Functional goals are a realistic expectation of activities that a person with SCI eventually should be able to do with a particular level of injury. These goals are set during rehabilitation with the medical team. They help the patient with SCI learn new ways to manage his/her daily activities and stay healthy. Developing independence is especially important to kids, particularly teenagers. Many hospitals have SCI units geared to help patients develop their independence, and SCI treatment centers are operational in several states with special programs for children. The SCI units include kitchens and laundry facilities and other equipment so that patients can learn independent living skills, such as cooking meals or ironing clothes. A spinal cord injury can also affect the nerves and muscles and can cause bowel and bladder problems and skin problems. Children are prepared for these changes during rehabilitation and are taught the self-care skills needed to deal with these problems. Parents of spinal cord injured children also need to learn how to take care of their spinal-cord injured child. Having a spinal cord injury does not mean that children have to stop participating in games and enjoyable activities. Most SCI units have recreational therapists on staff to show kids how to play wheelchair basketball, volleyball, and tennis, as well as specially adapted games.

Alternative treatment

People with spinal cord injuries caused by traumatic events have in the past been considered hopeless cases destined to a life of paralysis. But in the last decades of the twentieth century there were dramatic advances in spinal cord regeneration research. For example, Swiss scientist Martin Schwab actually managed to heal spinal cords in rats and restored their ability to walk. At the Swedish Karolinska Institute, scientists succeeded in constructing a bridge of slender nerve filaments to connect a once-severed spinal cord in rats that subsequently were able to flex their legs. These developments and others offer paralyzed people some hope. In the early 2000s envisioned treatments include an immune therapy procedure that has been tested in Israel with human subjects and possibilities for mechanical neural prostheses.

Acupuncture is a more conservative form of alternative treatment with documented evidence for the reduction of SCI-related muscle spasms , increased level of sensation, improved bladder and bowel function, improvement in lower limb paralysis, with younger patients reported to have better outcomes.

Nutritional concerns

Because of the changes that occur in the body after SCI, parents need to understand the role that nutrition can play in the overall health of a child following a spinal cord injury.

Special health concerns resulting from SCI are as follows:

  • Bowel management. Individuals with SCI may have neurogenic bowel, with the result that the messages from the brain that control the downward muscular movements of the bowel are either absent or not working properly, making it difficult for stool to move through the intestines. SCI diets accordingly include high fiber and plenty of fluids to regulate bowel movements.
  • Heart problems. SCI presents a greater risk for cardiovascular and heart problems, hence the necessity to limit salt and cholesterol intake.
  • Pressure ulcers. Pressure ulcers are always a concern to individuals with SCI and a diet high in protein, vitamins , and minerals is recommended to promote skin healing.
  • Kidney or bladder stones. Individuals with SCI may be prone to developing calcium stones. Certain beverages can cause crystals to form in the urine and excessive consumption of dairy products is accordingly avoided with water highly recommended as the best drink.
  • Urinary tract infection. The loss of normal bladder function after SCI places an individual at risk for urinary tract infection. A high fluid intake every day has been shown to reduce the problem of infections.
  • Weight control. After SCI, the metabolic rate is usually lower. Metabolic rate is how fast a body burns ingested calories. A lower muscle mass and a decrease in activities cause a lower metabolic rate, meaning that fewer calories are needed each day to maintain a desirable weight. After rehabilitation, the ideal body weight of a person with SCI is lower than for a nondisabled individual. Dieticians normally decrease the amount of calories by 5 percent for those with paraplegia and 10 to 15 percent for those with tetraplegia (quadriplegia).

Prognosis

The prognosis of SCI depends on the location and extent of injury. Once the initial injury heals, functional improvements may continue for at least six months. Any disability that remains after that point is likely to be permanent. Injuries of the neck above C4 with significant involvement of the diaphragm have worse outcomes. Although SCI often results in permanent disability, rehabilitation can maximize the level of function and help patients adapt and lead independent, productive lives.

According to the American Association of Neurological Surgeons, mortality from SCI is influenced by several factors, the most important being the severity of associated injuries. Because of the force that is required to fracture the spine, it is not uncommon for the patient to suffer significant damage to the chest and/or abdomen. Many of these associated injuries are fatal. For isolated SCIs, the mortality after one year is roughly 5 to 7 percent. If a patient survives the first 24 hours after injury, the probability of survival for ten years is approximately 75 to 80 percent. Likewise, the ten-year survival rate for patients who survived the first year after injury is 87 percent.

Prevention

The following guidelines have been shown to help prevent SCI:

  • use of safe driving practices
  • avoidance of situations that may become violent
  • keeping firearms locked away
  • taking precautions to prevent falls around the home (walkways free from obstacles, non-slip materials in bathtubs, etc)
  • use of proper safety equipment for sports

The American Academy of Orthopedic Surgeons (AAOS) also recommends that playgrounds be made safe to prevent spinal cord injuries. It offers the following checklist to help parents assess the safety of their child's playground:

  • Are any pieces of playground equipment missing supports, anchors, or footings?
  • Are any supports, anchors, or footings damaged or loose?
  • Has the wood started to splinter or rot?
  • Are surface materials missing or damaged?
  • Are there any missing, loose, or damaged nuts and bolts on the equipment?
  • Are any seats broken?
  • Are swing hangers and chains broken or worn?
  • Are hooks, rings, or links misshapen or deformed?
  • Are there any broken, missing, or loose steps?
  • Are any ladder rungs missing, broken, or loose?
  • Are tree roots visible or rocks sticking up that could cause a child to trip and fall?

If the answer to any of these questions is "Yes," this playground is not safe for a child. The AAOS recommends that the playground be reported to local park or school officials or to contact a local orthopedic surgeon to enquire as how to build a safe, accessible playground for the area.

Parental concerns

In most cases, SCI requires that the home be modified to be fully accessible to the injured child. Bathrooms need to be fitted with a shower chair, grab bars, a shower wand, a tub lift, or a shower bench. Grab bars should be installed on three sides of the shower, and non-skid strips should be applied to the bottom of the shower or tub. Bedrooms should be located for convenient access to the bathroom and adequate space should be provided around the bed for wheelchair access with convenient storage near the bed for braces, prostheses, and clothing. Light switches should be lowered for easy access and ramps should be built to facilitate displacements.

KEY TERMS

Axon A long, threadlike projection that is part of a neuron (nerve cell).

Central nervous system Part of the nervous system consisting of the brain, cranial nerves, and spinal cord. The brain is the center of higher processes, such as thought and emotion and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. The cranial nerves and spinal cord link the brain to the peripheral nervous system, that is the nerves present in the rest of body.

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; also called computed axial tomography.

Dendrite A threadlike extension of the cytoplasm of a neuron that conducts electrical impulses toward the cell body of the neuron. Usually it spreads out into many branches..

Gray matter Areas of the brain and spinal cord that are comprised mostly of unmyelinated nerves.

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 detailed images of internal body structures and organs, including the brain.

Methylpredisolone A steroid drug. Methylpredisolone administered within eight hours of acute spinal cord trauma is the first drug shown to improve recovery from spinal cord injury.

Myelin A fatty sheath surrounding nerves throughout the body that helps them conduct impulses more quickly.

Myelogram An x-ray image of the spinal cord, spinal canal, and nerve roots taken with the aid of a contrast dye.

Spina bifida A birth defect (a congenital malformation) in which part of the vertebrae fail to develop completely so that a portion of the spinal cord, which is normally protected within the vertebral column, is exposed. People with spina bifida can suffer from bladder and bowel incontinence, cognitive (learning) problems, and limited mobility.

Vertebrae Singular, vertebra. The individual bones of the spinal column that are stacked on top of each other. There is a hole in the center of each bone, through which the spinal cord passes.

White matter A substance, composed primarily of myelin fibers, found in the brain and nervous system that protects nerves and allows messages to be sent to and from the brain and various parts of the body. Also called white substance.

See also Computed tomography; Magnetic resonance imaging.

Resources

BOOKS

Nesathurai, Shanker. The Rehabilitation of People with Spinal Cord Injury. Oxford, UK: Blackwell Science, 2000.

Palmer, Sara, et al. Spinal Cord Injury: A Guide for Living. Baltimore, MD: Johns Hopkins University Press, 2000.

Somers, Martha Freeman. Spinal Cord Injury: Functional Rehabilitation. New York: Pearson Education, 2001.

Vikhanski, Luba. In Search of the Lost Cord: Solving the Mystery of Spinal Cord Regeneration. Washington, DC: Joseph Henry Press, 2001.

PERIODICALS

Bakun, M. and K. Haddix. "Spinal cord injury prevention with children and adolescents." SCI Nursing 20, no. 2 (Summer, 2003): 116118.

Beck, T. "Current spasticity management in children with spinal cord injury." SCI Nursing 19, no. 1 (Spring, 2002): 2831.

Cirak, B., et al. "Spinal injuries in children." Journal of Pediatric Surgery 39, no. 4 (April, 2004): 60712.

Dias, M. S. "Traumatic brain and spinal cord injury." Pediatric Clinics of North America 51, no. 2 (April, 2004): 271303.

Merenda, L. A., et al. "Progressive treatment options for children with spinal cord injury." SCI Nursing 17, no. 3 (Fall, 2000): 10209.

Vogel, L. C., and C. J. Anderson. "Spinal cord injuries in children and adolescents: a review." Journal of Spinal Cord Medicine 26, no. 3 (Fall, 2003): 193203.

. "Self-injurious behavior in children and adolescents with spinal cord injuries." Spinal Cord 40, no. 12 (December, 2002): 66668.

Wang, M. Y., et al. "High rates of neurological improvement following severe traumatic pediatric spinal cord injury." Spine 29, no. 13 (July, 2004): 149397.

ORGANIZATIONS

American Spinal Injury Association (ASIA). 2020 Peachtree Road NW, Atlanta, GA 303091402. Web site: <www.asia-spinalinjury.org>.

International Spinal Cord Regeneration Center. PO Box 451, Bonita, California 91902. Web site: <www.electriciti.com/~spinal>.

National Association for Home Care (NAHC). 228 7th Street SE, Washington, DC 20003. Web site: <www.nahc.org>.

National Institute of Neurological Disorders and Stroke (NINDS). PO Box 5801, Bethesda, MD 20824. Web site: <www.ninds.nih.gov>.

National Spinal Cord Injury Association (NSCIA). 6701 Democracy Blvd, Suite 3009, Bethesda, MD 20817. Web site: <www.spinalcord.org>.

Spinal Cord Society. 19051 County Highway 1, Fergus Falls, MN 565377609. Web site: <http://users.aol.com/scsweb>.

WEB SITES

"Spinal Cord Injury Rehabilitation." Shriner's Hospitals for Children. Available online at <http://www.shrinershq.org/hospitals/sci.html> (accessed October 13, 2004).

Monique Laberge, Ph.D.

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Laberge, Monique. "Spinal Cord Injury." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Encyclopedia.com. 29 Sep. 2016 <http://www.encyclopedia.com>.

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Spinal Cord Injury

Spinal Cord Injury

Definition

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

Description

Approximately 10,000 new spinal cord injuries (SCIs) occur each year in the United States. About 250,000 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 50% of all SCIs), a fall (20%), an act of violence (15%), or a sporting accident (14%). 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 lower spine die within a year, and 40% of people who receive the more frequent higher injuries 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 is about as big around as the index finger. It descends from the brain down the back through hollow channels of the backbone. The spinal cord is made of nerve cells (neurons). The nerve cells carry sensory data from the areas outside the spinal cord (periphery) to the brain, and they carry motor commands from brain to periphery. Peripheral neurons are bundled together to make up 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. Each pair of nerves is named for the vertebra from which it exits. These are known as:

  • C1-8. These nerves enter from the eight 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 they carry 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.) Damage to the spinal cord interrupts these signals. The interruption damages motor functions that allow the muscles to move, sensory functions such as feeling heat and cold, and autonomic functions such as 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 temporary spinal concussion. Concussion symptoms usually disappear completely within several hours. 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 some object, such as a tumor, pressing on the cord. Lacerations or tears cause direct damage to cord neurons. Lacerations can 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 base 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 or tetraplegia. 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 to breathe.

Symptoms also depend on the extent of spinal cord injury. 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.

DEEP VENOUS THROMBOSIS. Blood does not flow normally to 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.

PRESSURE ULCERS. Inability to move also leads to pressure ulcers or bed sores. Pressure 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.

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. Because 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.

AUTONOMIC DYSREFLEXIA. Body organs that regulate themselves, such as the heart, gastrointestinal tract, and glands, are controlled by groups of nerves called 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.

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. Both of these systems may be damaged by SCI. When the autonomic nervous system triggers an urge to urinate or defecate, continence is maintained by contracting the anal or urethral sphincters. A 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. However, the patient may not 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 rapid overwhelming infection.

SEXUAL DYSFUNCTION. Men who have sustained SCI may be unable to achieve an erection or ejaculate. Sperm formation may be abnormal too, reducing fertility. Fertility and the ability to achieve orgasm are less impaired for women. Women may still be able to become pregnant and deliver vaginally with proper medical care.

Diagnosis

The location and extent of spinal cord injury is determined with computed tomography scans (CT scans), magnetic resonance imaging (MRI) scans, and x rays. X rays may be enhanced with an injected contrast dye.

Treatment

A person who may have a spinal cord injury should not be moved. Treatment of SCI begins with immobilization. This strategy prevents partial injuries of the cord from severing it completely. Use of splints to completely immobilize suspected SCI at the scene of the injury has helped reduce the severity of spinal cord injuries in the last two decades. Intravenous methylprednisone, a steroidal anti-inflammatory drug, is given during the first 24 hours to reduce inflammation and tissue destruction.

Rehabilitation after spinal cord injury 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.

Paralysis and loss of sensation

Some limited mobility and sensation may be recovered, but the extent and speed of this recovery cannot be predicted. Experimental electrical stimulation has been shown 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.

The physical therapist focuses on mobility, to maintain range of motion of affected limbs and reduce contracture and deformity. Physical therapy helps compensate for lost skills by using those muscles that are still functional. It also helps to increase any residual strength and control in affected muscles. A physical therapist suggests adaptive equipment such as braces, canes, or wheelchairs.

An occupational therapist works to restore ability to perform the activities of daily living, such as eating and grooming, with tools and new techniques. The occupational therapist also designs modifications of the home and workplace to match the individual impairment.

A pulmonologist or respiratory therapist promotes airway hygiene through instruction in assisted coughing techniques and postural drainage. The respiratory professional also prescribes and provides instruction in the use of ventilators, facial or nasal masks, and tracheostomy equipment where necessary.

Pressure ulcers

Pressure ulcers are prevented by turning in bed at least every two hours. 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. Electrical stimulation is sometimes used to promote muscle movement to prevent pressure 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 onto the nerve or botulinum toxin 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 its pull will not cause as much deformity. Such tendon transfers may also be used to increase strength in partially functional extremities.

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

Autonomic dysreflexia is prevented by bowel and bladder care and attention to potential irritants. It is treated by prompt removal of the irritant. Drugs to lower blood pressure are used when necessary. People with SCI should educate friends and family members about the symptoms and treatment of dysreflexia, because immediate attention is 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 in adjusting to changes in sexual function after spinal cord injury. Erection may be enhanced through the same means used to treat erectile dysfunction in the general population.

Prognosis

The prognosis of SCI depends on the location 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 10 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.

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, and using seat belts.

Resources

ORGANIZATIONS

National Spinal Cord Injury Association. 8300 Colesville Road, Silver Spring, Maryland 20910. (301) 588-6959. http://www.erols.com/nscia.

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.

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Spinal Cord Injury

Spinal cord injury

Definition

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

Description

Approximately 10,000 new spinal cord injuries (SCIs) occur each year in the United States. About 250,000 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 50% of all SCIs), a fall (20%), an act of violence (15%), or a sporting accident (14%). Most SCI patients are white, but the nonwhite fraction of SCI patients is larger than the nonwhite fraction of the general population. 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 lower spine die within a year, and 40% of people who receive the more frequent higher injuries 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

The spinal cord is about as big around as the index finger. It descends from the brain down the back through hollow channels of the backbone. The spinal cord is made of nerve cells (neurons). The nerve cells carry sensory data from the areas outside the spinal cord (periphery) to the brain, and they carry motor commands from brain to periphery. Peripheral neurons are bundled together to make up 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. Each pair of nerves is named for the vertebra from which it exits. These are known as:

  • C1-8. These nerves enter from the eight 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 they carry 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.) Damage to the spinal cord interrupts these signals. The interruption damages motor functions that allow the muscles to move, sensory functions such as feeling heat and cold, and autonomic functions such as 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 temporary spinal concussion. Concussion symptoms usually disappear completely within several hours. 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 some object, such as a tumor, pressing on the cord. Lacerations or tears cause direct damage to cord neurons. Lacerations can 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.

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 base 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 or tetraplegia. 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 to breathe.

Symptoms also depend on the extent of spinal cord injury. 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.

DEEP VENOUS THROMBOSIS Blood does not flow normally to 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 .

PRESSURE ULCERS Inability to move also leads to pressure ulcers or bed sores. Pressure 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.

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 . Because 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.

AUTONOMIC DYSREFLEXIA Body organs that regulate themselves, such as the heart, gastrointestinal tract, and glands, are controlled by groups of nerves called 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.

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. Both of these systems may be damaged by SCI. When the autonomic nervous system triggers an urge to urinate or defecate, continence is maintained by contracting the anal or urethral sphincters. A 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. However, the patient may not 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 rapid overwhelming infection.

SEXUAL DYSFUNCTION Men who have sustained SCI may be unable to achieve an erection or ejaculate. Sperm formation may be abnormal too, reducing fertility. Fertility and the ability to achieve orgasm are less impaired for women. Women may still be able to become pregnant and deliver vaginally with proper medical care.

Diagnosis

The location and extent of spinal cord injury is determined with computed tomography scans (CT scans), magnetic resonance imaging (MRI ) scans, and x rays. X rays may be enhanced with an injected contrast dye.

Treatment

A person who may have a spinal cord injury should not be moved. Treatment of SCI begins with immobilization . This strategy prevents partial injuries of the cord from severing it completely. Use of splints to completely immobilize suspected SCI at the scene of the injury has helped reduce the severity of spinal cord injuries in the last two decades. Intravenous methylprednisone, a steroidal anti-inflammatory drug, is given during the first 24 hours to reduce inflammation and tissue destruction.

Rehabilitation after spinal cord injury 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.

Paralysis and loss of sensation

Some limited mobility and sensation may be recovered, but the extent and speed of this recovery cannot be predicted. Experimental electrical stimulation has been shown 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.

The physical therapist focuses on mobility, to maintain range of motion of affected limbs and reduce contracture and deformity. Physical therapy helps compensate for lost skills by using those muscles that are still functional. It also helps to increase any residual strength and control in affected muscles. A physical therapist suggests adaptive equipment such as braces, canes, or wheelchairs.

An occupational therapist works to restore ability to perform the activities of daily living, such as eating and grooming, with tools and new techniques. The occupational therapist also designs modifications of the home and workplace to match the individual impairment.

A pulmonologist or respiratory therapist promotes airway hygiene through instruction in assisted coughing techniques and postural drainage. The respiratory professional also prescribes and provides instruction in the use of ventilators, facial or nasal masks, and tracheostomy equipment where necessary.

Pressure ulcers

Pressure ulcers are prevented by turning in bed at least every two hours. 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. Electrical stimulation is sometimes used to promote muscle movement to prevent pressure 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 onto the nerve or botulinum toxin 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 its pull will not cause as much deformity. Such tendon transfers may also be used to increase strength in partially functional extremities.

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

Autonomic dysreflexia is prevented by bowel and bladder care and attention to potential irritants. It is treated by prompt removal of the irritant. Drugs to lower blood pressure are used when necessary. People with SCI should educate friends and family members about the symptoms and treatment of dysreflexia, because immediate attention is 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 in adjusting to changes in sexual function after spinal cord injury. Erection may be enhanced through the same means used to treat erectile dysfunction in the general population.

Prognosis

The prognosis of SCI depends on the location 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 10 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.

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, and using seat belts.

Resources

BOOKS

Bradley, Walter G., et al., eds. Neurology in Clinical Practice. 2nd ed. Boston: Butterworth-Heinemann, 1996.

Martini, F. Fundamentals of Anatomy and Physiology. Englewood Cliffs, NJ: Prentice Hall, 1989.

Yarkony, Gary M., ed. Spinal Cord Injury: Medical Management and Rehabilitation. Gaithersburg, MD: Aspen Publishers, Inc., 1994.

ORGANIZATIONS

The National Spinal Cord Injury Association. 8300 Colesville Road, Silver Spring, Maryland 20910. (301) 588-6959. <http://www.erols.com/nscia>.

Richard Robinson

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spinal shock

spinal shock The term ‘spinal shock’ refers to the fact that transection of the spinal cord produces an initially complete but temporary absence of spinal reflexes in body parts whose innervation arises from levels of the spinal cord below the level of transection. In current clinical usage, the state of spinal shock would never be considered in isolation, but together with the absence of voluntary movement in, and the loss of sensation from, corresponding regions of the body, it forms the basis of the clinical diagnosis of a functionally-complete transection of the spinal cord. This distinction between current and past usage is not without academic interest, as, historically and conceptually, spinal shock could not be understood until the ‘spinal reflex’ itself was fully defined and its nature investigated by experiment. Thus, although the phenomena of spinal shock were first described and investigated by the physician Whytt in 1750, its naming as such, by the physician and physiologist Marshall Hall, did not occur until a hundred years later. That naming was the outcome of animal experiments in which he clearly defined spinal reflex for the first time and later their counterpart cranial reflexes, such as the blink reflex. Whytt had recognized that mechanical stimulation of the foot in a decapitated frog resulted in withdrawal of the hindlimb. He termed such movements ‘vital motions’ and recognized that they depended on the spinal cord. However, in accord with lingering ideas of ‘vitalism’ (for which ‘soul’ corresponds to the contemporary usage of ‘consciousness’), he deemed the spinal cord to contain a sentient principle or ‘soul’. Hall, who can be regarded as the first professional physiologist, and wedded therefore to functional explanations, conceived a distinct class of ‘involuntary motions’, the spinal reflexes, that depended on ingoing influences to the spinal cord on the spinal cord itself, and on outgoing influences to the muscles (and glands); such ‘reflected’ actions were purposive in nature, but not dependent on sensory experience and hence not involving consciousness, which he attributed to the brain alone. Indeed, these and related experiments and philosophical enquiry all contributed to the then current debate as to whether movements induced by touching a part of the body (e.g. the tail) which, together with the spinal cord, had been surgically isolated from the rest of the body, were the result of a sensory experience, i.e. whether they concerned the ‘soul’. In contrast, Hall believed reflex action to be a manifestation of sensitivity to the stimulus but without sensibility; for him the ‘soul’ could not be so divided between brain and spinal cord.

As evident from the early experiments on the frog, spinal shock can be very transitory, lasting only for a few minutes, but it is of increasing duration according to cerebral dominance, lasting weeks in monkeys and still longer in apes and humans. In man the effect of injury of the spinal cord depends on whether it is completely or incompletely divided and on the level of the spinal cord that is affected. For example, with transection at the third cervical level or above, functions depending on the cranial nerves, such as swallowing and facial movements, persist, but all breathing movements cease and life sup-port by artificial ventilation is necessary. Speech remains possible, so long as a source of air pressure is provided below the vocal cords, to energize their oscillation when they are brought together (through activity of the still intact cranial nerves serving the larynx) as the patient attempts to speak. With transection a little lower, below the fourth cervical level, speech and also breathing are now independent because the brain stem motor control of the diaphragm remains mainly intact, via the phrenic nerve, whose motor neurons leave the cord mainly above this level; however all active expiratory-dependent activities, such as coughing, straining in defecation, and vocal power, remain absent, because the motor innervation of the relevant muscles lies below the transection. Even one segmental level can make a remarkable difference in the person's dependence on others or independence. A lesion at the seventh thoracic segment would leave the person independent for much of his personal needs, but standing unassisted and walking would be impossible, as would normal control of defecation and micturition. The ‘tendon jerk’ is important to the assessment of spinal transection, because normally it would be present in a range of muscles in the arms and legs. This allows the level of transection to be identified, along with other features, based on knowledge of the spinal segmental motor nerve supply to the individual muscles. Furthermore, extensive anatomical and physiological research has clearly established that the reflex pathway of the tendon jerk is monosynaptic. This means that when the muscle receptors are briefly stretched by the tap, the nerve impulses in the afferent pathway travel directly to the motor neurons and excite them reflexly to cause the normally visible muscle twitch. Thus the complete absence of this particular class of spinal reflex activity, in the initial phase of spinal shock that follows spinal transection, indicates how strongly in man motor neuron excitability is dependent on impulses descending from the brain stem and above.

However, not all the pathways are necessarily excitatory. The spinal neural circuitry is itself extremely complex, and some descending pathways may equally normally inhibit ‘inhibitory’ interneurons whose activity is then ‘released’ by the loss of the descending inhibitory control, causing the motor neurons to be inhibited. It is not surprising, therefore, that the basis of spinal shock remains an enigma; its unravelling would undoubtedly contribute to future attempts to restore — prosthetically, or biologically by cell transplantation, for example — useful function to spinal man. But until more research is done, any such interventions when first undertaken would be unlikely to be introduced at the time of ‘spinal shock’, because at that stage the final clinical outcome would remain uncertain if not unknown.

With regard to the reflexes, spinal shock is not permanent and spinal reflex activity is restored; this is a gradual process starting some weeks following the lesion. It is not simply as before but has a distinct bias in which increasingly the flexor muscles are readily thrown into reflex contraction by cutaneous stimulation or muscle stretch, the process commonly being first seen in the big toe (Babinski's sign) and ankle, and later in the knee and hip. Still later, reflexes return in the extensor muscles. Another aspect of this functional recovery is the enlargement of the receptive field of the cutaneous reflexes so that they can be elicited by minimal stimulation from a progressively wider area of skin. Spinal reflexes involving micturition and defecation are also affected during spinal shock. In particular the bladder is completely without its normal ‘tone’ and the immediate loss of the ‘voiding’ reflex, whose reflex pathway normally involves the brain stem, can result in overfilling of the bladder, with urination only by overflow if not managed clinically. Eventually, as spinal shock diminishes, a wholly spinal reflex emerges to create an ‘automatic bladder,’ which the patient can learn to empty by manual stimulation in the groin.

The study of spinal shock indicates the extraordinary capacity of the nervous system to reorganize after a lesion, and raises many important questions and theoretical concepts about the way the central nervous system functions. The International Spinal Research Trust (now usually known as ‘Spinal Research’) funds the majority of research in spinal cord injury and for further information readers are referred to this Trust.

L. S. Illis

Bibliography

Manuel, D. E. (1980). Marshall Hall, F. R. S. (1700–1857): a conspectus of his life and work. The Royal Society Notes and Records, 35, 135–65.
International Spinal Research Trust, Station Road, Bramley, Surrey, GU5 0AZ, UK. e-mail: isrt@spinal-research.org


See also breathing; central nervous system; paralysis; reflexes; spinal cord.

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Spinal Cord Injury

SPINAL CORD INJURY

DEFINITION


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

DESCRIPTION


About ten thousand new spinal cord injuries (SPI) occur each year in the United States. About 250,000 people currently have this condition. Spinal cord injury can happen to anyone at any time of life. The typical patient, however, is a man between the ages of nineteen and twenty-six. The most common causes of SPI are motor vehicle accidents (which are responsible for 50 percent of all cases), a fall (20 percent), an act of violence (15 percent), or a sporting accident (14 percent). Alcohol or drug abuse is involved in many of the accidents that result in spinal cord injuries.

About 6 percent of those who suffer injury to the lower spine die within a year while approximately 40 percent of those who suffer injury to the upper spine die within a year.

CAUSES


The spinal cord is a long rope-like piece of nervous tissue. It runs from the brain down the back. It is contained within the spinal column. The spinal column consists of a set of bones known as vertebrae (pronounced VUR-tuh-bray).

Pairs of nerves travel from the spinal cord to muscles in the arms, legs, and other parts of the body. Messages travel from muscles to the spinal cord and then to the brain along one set of nerves. Messages travel in the opposite direction, from brain to spine to muscles, along the other set of nerves.

Each pair of nerves is connected to the spinal cord in the space between two adjacent vertebrae. The nerves are named for the vertebrae where they enter the spinal cord. The five sets of nerves connecting to the spinal cord are defined as follows:

  • C1-8 nerves enter the spine near the eighth cervical vertebrae, located in the neck.
  • T1-12 nerves enter the spine near the thoracic vertebrae, located in the chest.
  • L1-5 nerves enter the spine near the lumbar vertebrae, in the lower back.
  • S1-5 nerves enter the spine through the sacral vertebrae, located in the pelvis region.
  • The coccygeal nerves (pronounced kock-SIHJ-ee-uhl) enter the spine through the coccyx, or tailbone.

Injury to the spinal cord may damage any one or more of these nerves. When nerves are damaged, messages can not travel from the brain to the body's muscles, or from the muscles to the brain. For example, a person may lose their sense of touch if nerve messages are not able to travel from the fingers to the brain. Or a person may lose the ability to walk if nerve messages can not travel from the brain to leg and foot muscles. Other functions, such as urination, sexual function, sweating, and blood pressure, may also be affected.

Spinal Cord Injury: Words to Know

Autonomic responses:
Bodily responses that occur automatically, without the need for a person to think about it.
Contracture:
Permanent tightening and shortening of a muscle.
Contusion:
A bruise.
Motor function:
A body function controlled by muscles.
Spasticity:
The permanent tightening of a joint into an abnormal position.
Spinal cord:
A long rope-like piece of nervous tissue that runs from the brain down the back.
Spinal transection:
A complete break in the spinal column.
Vertebrae:
Bones that make up the spinal column.

The spinal cord can be damaged in many ways. A sudden and violent jolt can cause a temporary spinal concussion. The symptoms of a concussion usually disappear completely in a few hours. Or the spinal cord can suffer a contusion. A contusion is a bruise that can cause bleeding in the spinal column. Such bleeding can produce pressure on nerve cells that can cause those cells to die.

Spinal compression is caused when an object such as a tumor or abnormal growth puts pressure on the spinal column. This compression can cause the death of nerve cells.

Some injuries can cause a laceration (tear) in the spinal column. In the most serious cases, the spinal cord can be torn apart. This type of injury is known as a spinal transection. A spinal cord injury can consist of any one or combination of these types of damage.

SYMPTOMS


The symptoms of SCI depend on two factors: where the damage occurs and how serious it is. For example, damage below the T1 nerves causes loss

of feeling and paralysis in the legs and the lower body. The T1 nerves lie at the base of the ribs. Arm and upper body movement is not affected by this kind of injury.

Damage to nerves below the C3 level of nerves may cause loss of feeling and paralysis of the arms as well as the legs and upper body. The C3 nerves are located in the middle of the neck. This kind of injury may also damage a person's chest muscles, making breathing difficult, but not impossible.

Damage above the C3 level may cause loss of feeling and paralysis throughout the body below the neck. A person with this kind of damage is not able to breathe on his or her own.

A spinal transection causes complete loss of feeling and muscle control. A person is completely paralyzed in the part of the body below the injury. For example, a person whose spinal cord is severed at T1 will be unable to move his or her legs or the lower part of the body. If the spine is injured but not severed, some feeling may remain.

Spinal cord injuries can cause many other kinds of symptoms, including:

  • Blood clots. Blood clots may form in veins when an arm or leg has been inactive for a long time. The clot may break loose and cause damage to the heart or lungs.
  • Pressure ulcers. Pressure ulcers are sores that develop when a person can not move for long periods of time.
  • Muscle stiffness. Spinal cord damage may make it impossible to move muscles normally. After a while, the muscles tend to become tight and shortened. This process is called a contracture. Eventually, the muscles become frozen in an abnormal and awkward position. When this happens, the muscle is said to be spastic.
  • Calcium deposits in muscles and tendons. Spinal cord injury may cause the growth of bone-like material in muscles and tendons. This growth may produce swelling, redness, heat, and stiffness in a muscle.
  • Failure of autonomic responses. Some body organs regulate themselves. The heart is an example. It automatically increases or decreases its rate of beating based on outside conditions, such as temperature. A person doesn't have to think about making these changes. They occur automatically. They are known as autonomic (self-controlling) responses. SCI can damage these systems. An organ may not respond the way it is supposed to. For example, pressure on the skin can cause organs to produce wild and uncontrolled responses. The patient may experience terrible headaches, nausea, anxiety, seating, and goose bumps. In extreme cases, these abnormal responses may lead to seizures, loss of consciousness, and even death.
  • Loss of bladder and bowel control. Bladder and bowel control are maintained by the use of certain muscles. Young children have to learn how to use these muscles when they become toilet-trained. SCI can cause damage to the nerves that control these muscles. A person may urinate or defecate without wanting to, or may not be able to urinate or defecate when he or she needs to.
  • Sexual dysfunction. Maintaining an erection requires control over muscles in the penis. If nerves are damaged, this control may not be possible. A man may not be able to have an erection. Sexual intercourse may become impossible. Women with spinal cord injuries, however may still be able to become pregnant, and can usually deliver a child with proper medical care.

DIAGNOSIS


Symptoms such as those listed above may suggest the presence of spinal cord injury. A final diagnosis is usually made using some form of imaging technique. An imaging technique is any method for studying the structure of an internal organ. For example, X rays may show the location and extent of damage to the spinal cord.

TREATMENT


The first step in treating spinal cord injuries is immobilization. Immobilization involves the use of splints, braces, or a cast to prevent the patient from moving. It keeps a spinal tear or injury from becoming worse. Steroid injections (shots) may be given to the patient as well. Steroids reduce inflammation and swelling, and this can prevent further damage to cells and tissues in the spinal cord. Immobilization and drug injections have greatly reduced the severity of spinal cord injuries in the last few decades.

There are currently no treatments that will make a spinal cord grow back to its normal condition. The most that can be done is to help people with spinal cord injuries avoid complications and to make the best use of those bodily functions they still control. Programs of this type often require a variety of professional workers, including a neurologist (specialist in nerve disorders), psychiatrist or psychologist, physical therapist and occupational therapist. Depending on the type of injury, a patient might also need the help of a respiratory therapist, speech-language specialist, nutritionist, special education teacher, or recreation therapist. Support groups also provide important information, advice, and emotional support for SCI patients. Support groups are made up of other individuals who have the same medical problem.

Some specific forms of rehabilitation (recovery) treatment include the following:

Paralysis and loss of feeling

Many patients with SCI can recover at least some of their ability to move. Physical therapists can teach patients how to use muscles that are still functional to take over for those that are not. The therapist can also help with exercises that will strengthen muscles that can still move. He or she also suggests equipment that may aid the patient's ability to move, such as braces, canes, or wheelchairs.

An occupational therapist teaches patients how to perform normal daily activities, such as eating and caring for oneself. The therapist may suggest changes in the person's home or work to make routine activities easier to perform.

A respiratory therapist helps SCI patients learn how to function with a weakened breathing system. For example, patients may learn new methods of coughing to make sure that disease-causing agents are eliminated from the lungs.

Pressure ulcers

Pressure ulcers (bedsores) often develop when a person is confined to bed for long periods of time. The sores can be prevented by turning the patient every two hours. Special chairs and mattresses are available that make pressure ulcers less likely.

Contracture and spasticity

Patients can be taught exercises that keep their muscles from becoming too stiff. In some cases, drug injections can help relax the muscle tissue. In extreme cases, surgery may be necessary to cut and/or replace tendons that have become too stiff.

Abnormal calcium deposits

A drug known as etidronate disodium (Didronel) helps control the way calcium is used in the body. When injected into SCI patients, it prevents calcium from depositing in muscles and tendons. In some cases, doctors may decide to remove abnormal calcium deposits by surgery.

Failure of autonomic responses

Patients and their families should learn to detect signs that autonomic responses are failing.

If not treated quickly, these failures can cause serious damage or death. Patients may need to be protected from conditions, such as exposure to the sun and pressure on the skin that may cause abnormal responses.

Sexual dysfunction

Counseling may help SCI patients to learn other forms of sexual behavior than traditional forms of intercourse. These alternative sexual behaviors can often be as satisfying as those with which the patient was familiar.

PROGNOSIS


The prognosis for spinal cord injury depends on two factors: the location of the injury and its extent. Injuries of the neck above the C4 nerves are the most dangerous. Patients often lose the ability to breathe on their own. The infection of the respiratory (breathing) tract that can result is the leading cause of death among patients with this type of spinal cord injury.

Overall, 85 percent of SCI patients who survive the first twenty-four hours after being injured are still alive ten years after the injury. How much control over bodily functions a patient recovers is impossible to predict. There more moderate the injury to the spinal cord, the greater chance for recovery.

PREVENTION


The vast majority of spinal cord injuries occur during accidents. As a result, it is difficult to prevent such injuries. Perhaps the most important step one can take is to use safety precautions that are available. For example, one should always wear a seat belt when traveling in a car. Also, one should wear protective equipment, such as helmets, when engaging in certain types of sports such as bike riding, roller-blading, and mountain climbing.

FOR MORE INFORMATION


Books

Reeve, Christopher. Still Me. New York: Random House, 1998.

Senelick, Richard C., and Karla Dougherty. The Healthsouth Spinal Cord Injury Handbook for Patients and Their Families. Birmingham, AL: Healthsouth Corporation, 1998.

Williams, Margie. Journey to Well: Learning to Live After Spinal Cord Injury. Newcastle, CA: Altarfire Publishing, 1998.

Organizations

The National Spinal Cord Injury Association. 8300 Colesville Road, Silver Springs, MD 20910. (301) 5886959. http://www.erols.com/nscia.

Other

"Ask NOAH About: Spinal Cord and Head Injuries." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu/neuro/spinal.html (accessed on October 31, 1999).

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spinal shock

spinal shock n. a state of shock accompanied by temporary paralysis of the lower extremities that results from injury to the spine and is often associated with ileus. If the spinal cord is transected, permanent motor paralysis persists below the level of spinal-cord division.

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