Back Pain Treatment - Treatment Of Spinal Cord Injury

Treatment of Spinal Cord Injury

Accounts of spinal cord injuries and their treatment date back to ancient times, even though there was little chance of recovery from such a devastating injury. The earliest is found in an Egyptian papyrus roll manuscript written in approximately 1700 B.C. that describes two spinal cord injuries involving fracture or dislocation of the neck vertebrae accompanied by paralysis. The description of each was "an ailment not to be treated."

Centuries later in Greece, treatment for spinal cord injuries had changed little. According to the Greek physician Hippocrates (460-377 B.C.) there were no treatment options for spinal cord injuries that resulted in paralysis; unfortunately, those patients were destined to die. But Hippocrates did use rudimentary forms of traction to treat spinal fractures without paralysis. The Hippocratic Ladder was a device that required the patient to be bound, tied to the rungs upside-down, and shaken vigorously to reduce spinal curvature. Another invention, the Hippocratic Board, allowed the doctor to apply traction to the immobilized patient's back using either his hands and feet or a wheel and axle arrangement. Hindu, Arab, and Chinese physicians also developed basic forms of traction to correct spinal deformities. These same principles of traction are still applied today.

In about 200 A.D., the Roman physician Galen introduced the concept of the central nervous system when he proposed that the spinal cord was an extension of the brain that carried sensation to the limbs and back. By the seventh century A.D., Paulus of Aegina was recommending surgery for spinal column fracture to remove the bone fragments that he was convinced caused paralysis. In his influential anatomy textbook published in 1543, the Renaissance physician and teacher Vesalius described and illustrated the spinal cord in all its parts. The illustrations in his books, based on direct observation and dissection of the spine, gave physicians a way to understand the basic structure of the spine and spinal cord and what could happen when it was injured. The words we use today to identify segments of the spine - cervical, thoracic, lumbar, sacral, and coccygeal - come directly from Vesalius.

With the widespread use of antiseptics and sterilization in surgical procedures in the late nineteenth century, spinal surgery could finally be done with a much lower risk of infection. The use of X-rays, beginning in the 1920s, gave surgeons a way to precisely locate the injury and also made diagnosis and prediction of outcome more accurate. By the middle of the twentieth century, a standard method of treating spinal cord injuries was established - reposition the spine, fix it in place, and rehabilitate disabilities with exercise. In the 1990s, the discovery that the steroid drug methylprednisolone could reduce damage to nerve cells if given early enough after injury gave doctors an additional treatment option.

What Is a Spinal Cord Injury?

Although the hard bones of the spinal column protect the soft tissues of the spinal cord, vertebrae can still be broken or dislocated in a variety of ways and cause traumatic injury to the spinal cord. Injuries can occur at any level of the spinal cord. The segment of the cord that is injured, and the severity of the injury, will determine which body functions are compromised or lost. Because the spinal cord acts as the main information pathway between the brain and the rest of the body, a spinal cord injury can have significant physiological consequences.

Catastrophic falls, being thrown from a horse or through a windshield, or any kind of physical trauma that crushes and compresses the vertebrae in the neck can cause irreversible damage at the cervical level of the spinal cord and below. Paralysis of most of the body including the arms and legs, called quadriplegia, is the likely result. Automobile accidents are often responsible for spinal cord damage in the middle back (the thoracic or lumbar area), which can cause paralysis of the lower trunk and lower extremities, called paraplegia. Other kinds of injuries that directly penetrate the spinal cord, such as gunshot or knife wounds, can either completely or partially sever the spinal cord and create life-long disabilities.

Most injuries to the spinal cord don't completely sever it. Instead, an injury is more likely to cause fractures and compression of the vertebrae, which then crush and destroy the axons, extensions of nerve cells that carry signals up and down the spinal cord between the brain and the rest of the body. An injury to the spinal cord can damage a few, many, or almost all of these axons. Some injuries will allow almost complete recovery. Others will result in complete paralysis.

Until World War II, a serious spinal cord injury usually meant certain death, or at best a lifetime confined to a wheelchair and an ongoing struggle to survive secondary complications such as breathing problems or blood clots. But today, improved emergency care for people with spinal cord injuries and aggressive treatment and rehabilitation can minimize damage to the nervous system and even restore limited abilities. Advances in research are giving doctors and patients hope that all spinal cord injuries will eventually be repairable. With new surgical techniques and exciting developments in spinal nerve regeneration, the future for spinal cord injury survivors looks brighter every day.

Facts and Figures About Spinal Cord Injury

* There are an estimated 10,000 to 12,000 spinal cord injuries every year in the United States.

* A quarter of a million Americans are currently living with spinal cord injuries.

* The cost of managing the care of spinal cord injury patients approaches $4 billion each year.

* 38.5 percent of all spinal cord injuries happen during car accidents. Almost a quarter, 24.5 percent, are the result of injuries relating to violent encounters, often involving guns and knifes. The rest are due to sporting accidents, falls, and work-related accidents.

* 55 percent of spinal cord injury victims are between 16 and 30 years old.

* More than 80 percent of spinal cord injury patients are men.

Spine Anatomy

The soft, jelly-like spinal cord is protected by the spinal column. The spinal column is made up of 33 bones called vertebrae, each with a circular opening similar to the hole in a donut. The bones are stacked one on top of the other and the spinal cord runs through the hollow channel created by the holes in the stacked bones. The vertebrae can be organized into sections, and are named and numbered from top to bottom according to their location along the backbone:

* Cervical vertebrae (1-7) located in the neck

* Thoracic vertebrae (1-12) in the upper back (attached to the ribcage)

* Lumbar vertebrae (1-5) in the lower back

* Sacral vertebrae (1-5) in the hip area

* Coccygeal vertebrae (1-4 fused) in the tailbone

Although the hard vertebrae protect the soft spinal cord from injury most of the time, the spinal column is not all hard bone. Between the vertebrae are discs of semi-rigid cartilage, and in the narrow spaces between them are passages through which the spinal nerves exit to the rest of the body. These are places where the spinal cord is vulnerable to direct injury.

The spinal cord is also organized into segments and named and numbered from top to bottom. Each segment marks where spinal nerves emerge from the cord to connect to specific regions of the body. Locations of spinal cord segments do not correspond exactly to vertebral locations, but they are roughly equivalent.

* Cervical spinal nerves (C1 to C8) control signals to the back of the head, the neck and shoulders, the arms and hands, and the diaphragm.

* Thoracic spinal nerves (T1 to T12) control signals to the chest muscles, some muscles of the back, and parts of the abdomen.

* Lumbar spinal nerves (L1 to L5) control signals to the lower parts of the abdomen and the back, the buttocks, some parts of the external genital organs, and parts of the leg.

* Sacral spinal nerves (S1 to S5) control signals to the thighs and lower parts of the legs, the feet, most of the external genital organs, and the area around the anus.

The single coccygeal nerve carries sensory information from the skin of the lower back.

Spinal Cord Anatomy

The spinal cord has a core of tissue containing nerve cells, surrounded by long tracts of nerve fibers consisting of axons. The tracts extend up and down the spinal cord, carrying signals to and from the brain. The average size of the spinal cord varies in circumference along its length from the width of a thumb to the width of one of the smaller fingers. The spinal cord extends down through the upper two thirds of the vertebral canal, from the base of the brain to the lower back, and is generally 15 to 17 inches long depending on an individual's height.

The interior of the spinal cord is made up of neurons, their support cells called glia, and blood vessels. The neurons and their dendrites (branching projections that help neurons communicate with each other) reside in an H-shaped region called "grey matter."

The H-shaped grey matter of the spinal cord contains motor neurons that control movement, smaller interneurons that handle communication within and between the segments of the spinal cord, and cells that receive sensory signals and then send information up to centers in the brain.

Surrounding the grey matter of neurons is white matter. Most axons are covered with an insulating substance called myelin, which allows electrical signals to flow freely and quickly. Myelin has a whitish appearance, which is why this outer section of the spinal cord is called "white matter."

Axons carry signals downward from the brain (along descending pathways) and upward toward the brain (along ascending pathways) within specific tracts. Axons branch at their ends and can make connections with many other nerve cells simultaneously. Some axons extend along the entire length of the spinal cord.

The descending motor tracts control the smooth muscles of internal organs and the striated (capable of voluntary contractions) muscles of the arms and legs. They also help adjust the autonomic nervous system's regulation of blood pressure, body temperature, and the response to stress. These pathways begin with neurons in the brain that send electrical signals downward to specific levels of the spinal cord. Neurons in these segments then send the impulses out to the rest of the body or coordinate neural activity within the cord itself.

The ascending sensory tracts transmit sensory signals from the skin, extremities, and internal organs that enter at specific segments of the spinal cord. Most of these signals are then relayed to the brain. The spinal cord also contains neuronal circuits that control reflexes and repetitive movements, such as walking, which can be activated by incoming sensory signals without input from the brain.

The circumference of the spinal cord varies depending on its location. It is larger in the cervical and lumbar areas because these areas supply the nerves to the arms and upper body and the legs and lower body, which require the most intense muscular control and receive the most sensory signals.

The ratio of white matter to grey matter also varies at each level of the spinal cord. In the cervical segment, which is located in the neck, there is a large amount of white matter because at this level there are many axons going to and from the brain and the rest of the spinal cord below. In lower segments, such as the sacral, there is less white matter because most ascending axons have not yet entered the cord, and most descending axons have contacted their targets along the way.

To pass between the vertebrae, the axons that link the spinal cord to the muscles and the rest of the body are bundled into 31 pairs of spinal nerves, each pair with a sensory root and a motor root that make connections within the grey matter. Two pairs of nerves - a sensory and motor pair on either side of the cord - emerge from each segment of the spinal cord.

The functions of these nerves are determined by their location in the spinal cord. They control everything from body functions such as breathing, sweating, digestion, and elimination, to gross and fine motor skills, as well as sensations in the arms and legs.

The Nervous Systems

Together, the spinal cord and the brain make up the central nervous system (CNS). The CNS controls most functions of the body, but it is not the only nervous system in the body. The peripheral nervous system (PNS) includes the nerves that project to the limbs, heart, skin, and other organs outside the brain. The PNS controls the somatic nervous system, which regulates muscle movements and the response to sensations of touch and pain, and the autonomic nervous system, which provides nerve input to the internal organs and generates automatic reflex responses. The autonomic nervous system is divided into the sympathetic nervous system, which mobilizes organs and their functions during times of stress and arousal, and the parasympathetic nervous system, which conserves energy and resources during times of rest and relaxation.

The spinal cord acts as the primary information pathway between the brain and all the other nervous systems of the body. It receives sensory information from the skin, joints, and muscles of the trunk, arms, and legs, which it then relays upward to the brain. It carries messages downward from the brain to the PNS, and contains motor neurons, which direct voluntary movements and adjust reflex movements. Because of the central role it plays in coordinating muscle movements and interpreting sensory input, any kind of injury to the spinal cord can cause significant problems throughout the body.

What Happens When the Spinal Cord Is Injured?

A spinal cord injury usually begins with a sudden, traumatic blow to the spine that fractures or dislocates vertebrae. The damage begins at the moment of injury when displaced bone fragments, disc material, or ligaments bruise or tear into spinal cord tissue. Axons are cut off or damaged beyond repair, and neural cell membranes are broken. Blood vessels may rupture and cause heavy bleeding in the central grey matter, which can spread to other areas of the spinal cord over the next few hours.

Within minutes, the spinal cord swells to fill the entire cavity of the spinal canal at the injury level. This swelling cuts off blood flow, which also cuts off oxygen to spinal cord tissue. Blood pressure drops, sometimes dramatically, as the body loses its ability to self-regulate. As blood pressure lowers even further, it interferes with the electrical activity of neurons and axons. All these changes can cause a condition known as spinal shock that can last from several hours to several days.

Although there is some controversy among neurologists about the extent and impact of spinal shock, and even its definition in terms of physiological characteristics, it appears to occur in approximately half the cases of spinal cord injury, and it is usually directly related to the size and severity of the injury. During spinal shock, even undamaged portions of the spinal cord become temporarily disabled and can't communicate normally with the brain. Complete paralysis may develop, with loss of reflexes and sensation in the limbs.

The crushing and tearing of axons is just the beginning of the devastation that occurs in the injured spinal cord and continues for days. The initial physical trauma sets off a cascade of biochemical and cellular events that kills neurons, strips axons of their myelin insulation, and triggers an inflammatory immune system response. Days or sometimes even weeks later, after this second wave of damage has passed, the area of destruction has increased - sometimes to several segments above and below the original injury - and so has the extent of disability.

Changes in blood flow cause ongoing damage

Changes in blood flow in and around the spinal cord begin at the injured area, spread out to adjacent, uninjured areas, and then set off problems throughout the body.

Immediately after the injury, there is a major reduction in blood flow to the site, which can last for as long as 24 hours and becomes progressively worse if untreated. Because of differences in tissue composition, the impact is greater on the interior grey matter of the spinal cord than on the outlying white matter.

Blood vessels in the grey matter also begin to leak, sometimes as early as 5 minutes after injury. Cells that line the still-intact blood vessels in the spinal cord begin to swell, for reasons that aren't yet clearly understood, and this continues to reduce blood flow to the injured area. The combination of leaking, swelling, and sluggish blood flow prevents the normal delivery of oxygen and nutrients to neurons, causing many of them to die.

The body continues to regulate blood pressure and heart rate during the first hour to hour-and-a-half after the injury, but as the reduction in the rate of blood flow becomes more widespread, self-regulation begins to turn off. Blood pressure and heart rate drop.

Excessive release of neurotransmitters kills nerve cells

After the injury, an excessive release of neurotransmitters (chemicals that allow neurons to signal each other) can cause additional damage by overexciting nerve cells.

Glutamate is an excitatory neurotransmitter, commonly used by nerve cells in the spinal cord to stimulate activity in neurons. But when spinal cells are injured, neurons flood the area with glutamate for reasons that are not yet well understood. Excessive glutamate triggers a destructive process called excitotoxicity, which disrupts normal processes and kills neurons and other cells called oligodendrocytes that surround and protect axons.

An invasion of immune system cells creates inflammation

Under normal conditions, the blood-brain barrier (which tightly controls the passage of cells and large molecules between the circulatory and central nervous systems) keeps immune system cells from entering the brain or spinal cord. But when the blood-brain barrier is broken by blood vessels bursting and leaking into spinal cord tissue, immune system cells that normally circulate in the blood - primarily white blood cells - can invade the surrounding tissue and trigger an inflammatory response. This inflammation is characterized by fluid accumulation and the influx of immune cells - neutrophils, T-cells, macrophages, and monocytes.

Neutrophils are the first to enter, within about 12 hours of injury, and they remain for about a day. Three days after the injury, T-cells arrive. Their function in the injured spinal cord is not clearly understood, but in the healthy spinal cord they kill infected cells and regulate the immune response. Macrophages and monocytes enter after the T-cells and scavenge cellular debris.

The up side of this immune system response is that it helps fight infection and cleans up debris. But the down side is that it sets off the release of cytokines - a group of immune system messenger molecules that exert a malign influence on the activities of nerve cells.

For example, microglial cells, which normally function as a kind of on-site immune cell in the spinal cord, begin to respond to signals from these cytokines. They transform into macrophage-like cells, engulf cell debris, and start to produce their own pro-inflammatory cytokines, which then stimulate and recruit other microglia to respond.

Injury also stimulates resting astrocytes to express cytokines. These "reactive" astrocytes may ultimately participate in the formation of scar tissue within the spinal cord.

Whether or not the immune response is protective or destructive is controversial among researchers. Some speculate that certain types of injury might evoke a protective immune response that actually reduces the loss of neurons.

* Free radicals attack nerve cells

Another consequence of the immune system's entry into the CNS is that inflammation accelerates the production of highly reactive forms of oxygen molecules called free radicals. Free radicals are produced as a by-product of normal cell metabolism. In the healthy spinal cord their numbers are small enough that they cause no harm. But injury to the spinal cord, and the subsequent wave of inflammation that sweeps through spinal cord tissue, signals particular cells to overproduce free radicals. Free radicals then attack and disable molecules that are crucial for cell function - for example, those found in cell membranes - by modifying their chemical structure. Free radicals can also change how cells respond to natural growth and survival factors, and turn these protective factors into agents of destruction.

* Nerve cells self-destruct

Researchers used to think that the only way in which cells died during spinal cord injury was as a direct result of trauma. But recent findings have revealed that cells in the injured spinal cord also die from a kind of programmed cell death called apoptosis, often described as cellular suicide, that happens days or weeks after the injury.

Apoptosis is a normal cellular event that occurs in a variety of tissues and cellular systems. It helps the body get rid of old and unhealthy cells by causing them to shrink and implode. Nearby scavenger cells then gobble up the debris. Apoptosis seems to be regulated by specific molecules that have the ability to either start or stop the process. For reasons that are still unclear, spinal cord injury sets off apoptosis, which kills oligodendrocytes in damaged areas of the spinal cord days to weeks after the injury. The death of oligodendrocytes is another blow to the damaged spinal cord, since these are the cells that form the myelin that wraps around axons and speeds the conduction of nerve impulses. Apoptosis strips myelin from intact axons in adjacent ascending and descending pathways, which further impairs the spinal cord's ability to communicate with the brain.

* Secondary damage takes a cumulative toll

All of these mechanisms of secondary damage - restricted blood flow, excitotoxicity, inflammation, free radical release, and apoptosis - increase the area of damage in the injured spinal cord. Damaged axons become dysfunctional, either because they are stripped of their myelin or because they are disconnected from the brain. Glial cells cluster to form a scar, which creates a barrier to any axons that could potentially regenerate and reconnect. A few whole axons may remain, but not enough to convey any meaningful information to the brain. Researchers are especially interested in studying the mechanisms of this wave of secondary damage because finding ways to stop it could save axons and reduce disabilities. This could make a big difference in the potential for recovery.

What Are the Immediate Treatments for Spinal Cord Injury?

The outcome of any injury to the spinal cord depends upon the number of axons that survive: the higher the number of normally functioning axons, the less the amount of disability. Consequently, the most important consideration when moving people to a hospital or trauma center is preventing further injury to the spine and spinal cord.

Spinal cord injury isn't always obvious. Any injury that involves the head (especially with trauma to the front of the face), pelvic fractures, penetrating injuries in the area of the spine, or injuries that result from falling from heights should be suspect for spinal cord damage.

Until imaging of the spine is done at an emergency or trauma center, people who might have spinal cord injury should be cared for as if any significant movement of the spine could cause further damage. They are usually transported in a recumbent (lying down) position, with a rigid collar and backboard immobilizing the spine.

Respiratory complications are often an indication of the severity of spinal cord injury. About one third of those with injury to the neck area will need help with breathing and require respiratory support via intubation, which involves inserting a tube connected to an oxygen tank through the nose or throat and into the airway.

Methylprednisolone, a steroid drug, became standard treatment for acute spinal cord injury in 1990 when a large-scale clinical trial supported by the National Institute of Neurological Disorders and Stroke showed significantly better recovery in patients who were given the drug within the first 8 hours after their injury. Methylprednisolone appears to reduce the damage to nerve cells and decreases inflammation near the injury site by suppressing activities of immune cells.

Realignment of the spine using a rigid brace or axial traction is usually done as soon as possible to stabilize the spine and prevent additional damage.

On about the third day after the injury, doctors give patients a complete neurological examination to diagnose the severity of the injury and predict the likely extent of recovery. The ASIA Impairment Scale is the standard diagnostic tool used by doctors. X-rays, MRIs, or more advanced imaging techniques are also used to visualize the entire length of the spine.

ASIA (American Spinal Injury Association) Impairment Scale, Classification and Description

A: Complete: no motor or sensory function is preserved below the level of injury, including the sacral segments S4-S5

B: Incomplete: sensory, but not motor, function is preserved below the neurologic level and some sensation in the sacral segments S4-S5

C: Incomplete: motor function is preserved below the neurologic level, however, more than half of key muscles below the neurologic level have a muscle grade less than 3 (i.e., not strong enough to move against gravity)

D: Incomplete: motor function is preserved below the neurologic level, and at least half of key muscles below the neurologic level have a muscle grade of 3 or more (i.e., joints can be moved against gravity)

E: Normal: motor and sensory functions are normal

Spinal cord injuries are classified as either complete or incomplete, depending on how much cord width is injured. An incomplete injury means that the ability of the spinal cord to convey messages to or from the brain is not completely lost. People with incomplete injuries retain some motor or sensory function below the injury. A complete injury is indicated by a total lack of sensory and motor function below the level of injury.

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