Spinal cord 101

 

 

 

 

What is Spinal Cord Injury?   Spinal Cord Injury (SCI) is damage to the spinal cord that results in a loss of function such as mobility or feeling. Frequent causes of damage are trauma (car accident, gunshot, falls, etc.) or disease (polio, spina bifida, Friedreich's Ataxia, etc.). The spinal cord does not have to be severed in order for a loss of functioning to occur. In fact, in most people with SCI, the spinal cord is intact, but the damage to it results in loss of functioning. SCI is very different from back injuries such as ruptured disks, spinal stenosis or pinched nerves.
    A person can "break their back or neck" yet not sustain a spinal cord injury if only the bones around the spinal cord (the vertebrae) are damaged, but the spinal cord is not affected. In these situations, the individual may not experience paralysis after the bones are stabilized.
Vertebradiagram    What is the spinal cord and the vertebra?   The spinal cord is about 18 inches long and extends from the base of the brain, down the middle of the back, to about the waist. The nerves that lie within the spinal cord are upper motor neurons (UMNs) and their function is to carry the messages back and forth from the brain to the spinal nerves along the spinal tract.  The spinal nerves that branch out from the spinal cord to the other parts of the body are called lower motor neurons (LMNs). These spinal nerves exit and enter at each vertebral level and communicate with specific areas of the body. The sensory portions of the LMN carry messages about sensation from the skin and other body parts and organs to the brain. The motor portions of the LMN send messages from the brain to the various body parts to initiate actions such as muscle movement.
 
    The spinal cord is the major bundle of nerves that carry nerve impulses to and from the brain to the rest of the body. The brain and the spinal cord constitute the Central Nervous System. Motor and sensory nerves outside the central nervous system constitute the Peripheral Nervous System, and another diffuse system of nerves that control involuntary functions such as blood pressure and temperature regulation are the Sympathetic and Parasympathetic Nervous Systems.
    The spinal cord is surrounded by rings of bone called vertebra. These bones constitute the spinal column (back bones). In general, the higher in the spinal column the injury occurs, the more dysfunction a person will experience. The  vertebra are named according to their location. The eight vertebra in the neck are called the Cervical Vertebra. The top vertebra is called C-1, the next is C-2, etc. Cervical SCI's usually cause loss of function in the arms and legs, resulting in quadriplegia. The twelve vertebra in the chest  are called the Thoracic Vertebra. The first thoracic vertebra, T-1, is the vertebra where the top rib attaches.
      Injuries in the thoracic region usually affect the chest and the legs and result in paraplegia. The vertebra in the lower back between the thoracic vertebra, where the ribs attach, and the pelvis (hip bone), are the Lumbar Vertebra. The sacral vertebra run from the Pelvis to the end of the spinal column. Injuries to the five Lumbar vertebra (L-1 thru L-5) and  similarly to the five Sacral Vertebra (S-1 thru S-5) generally result in some loss of functioning in the hips and legs.
spinal map What are the effects of SCI?   The effects of SCI depend on the type of injury and the level of the injury. SCI can be divided into two types of injury - complete and incomplete. A complete injury means that there is no function below the level of the injury; no sensation and no voluntary movement. Both sides of the body are equally affected. An incomplete injury means that there is some functioning below the primary level of the injury. A person with an incomplete injury may be able to move one limb more than another, may be able to feel parts of the body that cannot be moved, or may have more functioning on one side of the body than the other. With the advances in acute treatment of SCI, incomplete injuries are becoming more common.
      The level of injury is very helpful in predicting what parts of the body might be affected by paralysis and loss of function. Remember that in incomplete injuries there will be some variation in these prognoses.
      Cervical (neck) injuries usually result in quadriplegia. Injuries above the C-4 level may require a ventilator for the person to breathe. C-5 injuries often result in shoulder and biceps control, but no control at the wrist or hand. C-6 injuries generally yield wrist control, but no hand function. Individuals with C-7 and T-1 injuries can straighten their arms but still may have dexterity problems with the hand and fingers. Injuries at the thoracic level and below result in paraplegia, with the hands not affected. At T-1 to T-8 there is most often control of the hands, but poor trunk control as the result of lack of abdominal muscle control. Lower T-injuries (T-9 to T-12) allow good truck control and good abdominal muscle control. Sitting balance is very good. Lumbar and Sacral injuries yield decreasing control of the hip flexors and legs.
      Besides a loss of sensation or motor functioning, individuals with SCI also experience other changes. For example, they may experience dysfunction of the  bowel and bladder,. Sexual functioning is frequently with SCI may have their fertility affected, while women's fertility is generally not affected. Very high injuries (C-1, C-2) can result in a loss of many involuntary functions including the ability to breathe, necessitating breathing aids such as mechanical ventilators or diaphragmatic pacemakers. Other effects of SCI may include low blood pressure, inability to regulate blood pressure effectively, reduced control of body temperature,   inability to sweat below the level of injury, and chronic pain
 How many people have SCI?  Who are they? Approximately 450,000 people live with SCI in the US. There are about 10,000 new SCI's every year; the majority of them (82%) involve males between the ages of 16-30. These injuries result from motor vehicle accidents (36%), violence (28.9%), or falls (21.2%).Quadriplegia is slightly more common than paraplegia.   

 

Is there a cure?  Currently there is no cure for SCI. There are researchers attacking this problem, and there have been many advances in the lab (see research updates ). Many of the most exciting  advances have resulted in a decrease in damage at the time of the injury. Steroid drugs such as methylprednisolone reduce swelling, which is a common cause of secondary damage at the time of injury. The experimental drug SygenÆappears to reduce loss of function, although the mechanism is not completely understood.
 
  Do people with SCI ever get better?  When a SCI occurs, there is usually swelling of the spinal cord. This may cause changes in virtually every system in the body. After days or weeks, the swelling begins to go down and people may regain some functioning. With many injuries, especially incomplete injuries, the individual may recover some functioning as late as 18 months after the injury. In very rare cases, people with SCI will regain some functioning years after the injury. However, only a very small fraction of individuals sustaining SCIs recover all functioning.
 
  Does everyone who sustains SCI use a wheelchair?  No. Wheelchairs are a tool for mobility. High C-level injuries usually require that the individual use a power wheelchair. Low C-level injuries and below usually allow the person to use a manual chair. Advantages of manual chairs are that they cost less, weigh less, disassemble into smaller pieces and are more agile. However, for the person who needs a powerchair, the independence afforded by them is worth the limitations. Some people are able to use braces and crutches for ambulation. These methods of mobility do not mean that the person will never use a wheelchair. Many people who use braces still find wheelchairs more useful for longer distances. However, the therapeutic and activity levels allowed by standing or walking briefly may make braces a reasonable alternative for some people.
    Of course, people who use wheelchairs aren't always in them. They drive, swim, fly planes, ski, and do many activities out of their chair. If you hang around people who use wheelchairs long enough, you may see them sitting in the grass pulling weeds, sitting on your couch, or playing on the floor with children or pets. And of course, people who use wheelchairs don't sleep in them, they sleep in a bed. No one is "wheelchair bound."
 
  Do people with SCI die sooner?
 
   Yes. Before World War II, most people who sustained SCI died within weeks of their injury due to urinary dysfunction, respiratory infection or bedsores. With the advent of modern antibiotics, modern materials such as plastics and latex, and better procedures for dealing with the everyday issues of living with SCI, many people approach the lifespan of non-disabled individuals. Interestingly, other than level of injury, the type of rehab facility used is the greatest indicator of long-term survival. This illustrates the importance of and the difference made by going to a facility that specializes in SCI. People who use vents are at some increased danger of dying from pneumonia or respiratory infection, but modern technology is improving in that area as well. Pressure sores (learn more about pressure soars here) are another common cause of hospitalization, and if not treated - death.
    Overall, 85% of SCI patients who survive the first 24 hours are still alive 10 years later. The most common cause of death is due to diseases of the respiratory system, with most of these being due to pneumonia. In fact, pneumonia is the single leading cause of death throughout the entire 15 year period immediately following SCI for all age groups, both males and females, whites and non-whites, and persons with quadriplegia.
    The second leading cause of death is non-ischemic heart disease. These are almost always unexplained heart attacks often occurring among young persons who have no previous history of underlying heart disease.
    Deaths due to external causes is the third leading cause of death for SCI patients. These include subsequent unintentional injuries, suicides and homicides, but do not include persons dying from multiple injuries sustained during the original accident. The majority of these deaths are the result of suicide.
 
 Do people with SCI have jobs?  People with SCI have the same desires as other people. That includes a desire to work and be productive. The Americans with Disabilities Act (ADA) promotes the inclusion of people with SCI to mainstreamin day-to-day society. Of course, people with disabilities may need some changes to make their workplace more accessible, but surveys indicate that the cost of making accommodations to the workplace in 70% of cases is $500 or less.

 

Basic anatomy of the spinal cord:

   Introduction:- The spine works as the main support for the spinal cord and the nerve pathways that carry information from the arms, legs, and rest of the body, and carries signals from the brain to the body.

   Your back is composed of 33 bones called vertebrae, 31 pairs of nerves, 40 muscles and numerous connecting tendons and ligaments running from the base of your skull to your tailbone. Between your vertebrae are fibrous,  elastic cartilage called discs. These "shock absorbers" keep your spine flexible and cushion the hard vertebrae as you move.

anatomy1

 


anatomy2Bony Anatomy

Cervical Spine
   There are seven cervical bones or vertebrae. The cervical bones are designed to allow flexion, extension, bending, and turning of the head. They are smaller than the other vertebrae, which allows a greater amount of movement.
   Each cervical vertebra consists of two parts, a body and a protective arch for the spinal cord called the neural arch. Fractures or injuries can occur to the body, lim pedicles, or processes. Each vertebra articulates with the one above it and the one below it.
Thoracic Spine
   In the chest region the thoracic spine attaches to the ribs. There are 12 vertebrae in the thoracic region. The spinal canal in the thoracic region is relatively smaller than the cervical or lumbar areas. This makes the thoracic spinal cord at greater risk if there is a fracture.
   The motion that occurs in the thoracic spine is mostly rotation. The ribs prevent bending to the side. A small amount of movement occurs in bending forward and backward.
Lumbosacral Spine
   The lumbar vertebrae are large, wide, and thick. There are five vertebrae in the lumbar spine. The lowest lumbar vertebra, L5, articulates with the sacrum. The sacrum attaches to the pelvis. The main motions of the lumbar area are bending forward and extending backwards. Bending to the side also occurs…


Neuroanatomy:  Just like the spinal column is divided into cervical, thoracic, and lumbar regions, spinal mapso is the spinal cord. Each portion of the spinal cord is divided into specific neurological segments.The cervical spinal cord is divided into eight levels. Each level contributes to different functions in the neck and the arms (see diagram). Sensations from the body are similarly transported from the skin and other areas of the body from the neck, shoulders, and arms up to the brain.In the thoracic region the nerves of the spinal cord supply muscles of the chest that help in breathing and coughing. This region also contains nerves in the sympathetic nervous system.

  The lumbosacral spinal cord and nerve supply legs, pelvis, and bowel and bladder. Sensations from the feet, legs, pelvis, and lower abdomen are transmitted through the lumbosacral nerves and spinal cord to higher segments and eventually the brain

Nerve Pathways- There are many nerve pathways that transmit signals up and down the spinal cord. Some supply sensation from the skin and outer portions of the body. Others supply sensation from deeper structures such as the organs in the belly, the pelvis, or other areas. Other nerves transmit signals from the brain to the body. Still others work at the level of the spinal cord and act as "go betweens" in the signal transmission process.

The Motor Neuron-  The upper motor neuron refers to injuries that are above the level of the anterior horn cell. This results in a spastic type of paralysis. Conversely, the lower motor neuron injury refers to an injury at or below the anterior horn cell that results in the flaccid type paralysis. This is usually seen in nerve root injuries or in the cauda equina syndrome that was mentioned previously. The terms neurogenic bowel and neurogenic bladder are used to describe abnormal bowel and bladder function and can be classified as either an upper motor neuron or lower motor neuron type of problem. In general, those patients with an upper motor neuron paralysis will have an upper motor neuron bowel and bladder, and those with lower motor neuron injuries will have a lower motor neuron picture of the bowel and bladder. Adequate bowel and bladder management is critical for adequate reintegration of the patient/client into the community and hopefully into the work place.

Sensory Pathways:  Feelings from the body such as hot, cold, pain, and touch, are transmitted to the skin and other parts of the body to the brain where sensations are "felt." These pathways are called the sensory pathways.

  Once signals enter the spinal cord, they are sent up to the brain. Different types of sensation are sent in different pathways, called "tracts." The tracts that carry sensations of pain and temperature to the brain are in the middle part of the spinal cord. These tracts are called the "spinothalamic." Other tracts carry sensation of position and light touch. These nerve impulses are carried along the back part of the spinal cord in what are called "dorsal columns" of the spinal cord.

Autonomic Nerve Pathways:  Another type of special nerves are the autonomic nerves. In spinal cord injuries, they are very important. The autonomic nerves are divided into two types: the sympathetic and parasympathetic nerves.

  The autonomic nervous system influences the activities of involuntary (also known as smooth) muscles, the heart muscle, and glands that release certain hormones. It controls cardiovascular, digestive, and respiratory systems. These systems work in a generally "involuntary" fashion. The primary role of the autonomic nervous system is to maintain a stable internal environment within the body. The heart and blood vessels are controlled by the autonomic nervous system. The sympathetic nerves help to control blood pressure based on the physical demands placed on the body. It also helps to control heart rate. The sympathetic nerves, when stimulated, cause the heart to beat faster.

Sympathetic Nerves:  The sympathetic nerves also cause constriction of the blood vessels throughout the body. When this happens, the amount of blood that is returned to the heart increases. These effects will increase blood pressure. Other effects include an increase in sweating and increased irritability or a sensation of anxiety.

  When spinal cord injury is at or above the T6 level the sympathetic nerves below the injury become disconnected from the nerves above. They continue to operate automatically once the period of spinal shock is over. Anything that simulates the sympathetic nerves can cause them to become overactive. This overactivity of the sympathetic nerves is what is called autonomic dysreflexia.

Parasympathetic Nerves:  The parasympathetic nerves act in an opposite manner to the sympathetic nerves. These nerves tend to dilate blood vessels and slow down the heart. The most important nerve that carries sympathetic fibers is the vagus nerve. This nerve carries parasympathetic signals to the heart to decrease heart rate. Other nerves supply the blood vessels to the organs of the abdomen and skin.

  The parasympathetic nerves arise from two areas. The fibers that supply the organs of the abdomen, heart, lungs, and skin above the waist begin at the level of the brain and very high spinal cord. The nerves that supply the reproductive organs, pelvis, and leg begin at the sacral level, or lowest part of the spinal cord. After a spinal cord injury, the parasympathetic nerves that begin at the brain continue to work, even during the phase of spinal shock. When dysreflexia occurs, the parasympathetic nerves attempt to control rapidly increasing blood pressure by slowing down the heart.

Possible complications:

Skin Breakdown: Skin breakdowns (also termed "decubitus ulcers" or "pressure sores" ) are a major complication associated with spinal cord injury. They occur as a result of excessive pressure, primarily over the bones of the buttock (particularly the ischial tuberosities and the trochanters at the hip). Following a spinal cord injury, there are not only changes in muscle tone and sensation, but shifts in the supply of blood to the skin and subcutaneous tissues. Additionally, there is a loss of the normal elastic nature of the tissues underlying the skin. Increased stiffness, vascular alterations and alterations in muscle tone combine to significantly reduce the skin's ability to withstand pressure. It is estimated that the closing "pressure" for skin breakdown is between 40 and 50 millimeters of mercury (about the same amount of pressure as placing a stamp onto an envelope). This complication is combated fairly aggressively through the use of pressure-relieving cushions that are either gel based or consist of a number of air bladders to reduce risk of the person "bottoming out". The cost associated with medical and/or surgical care of a single decubitus ulcer can run anywhere from $10,000 to $50,000 per admission. This does not take into consideration the loss of productivity if the individual is in the work place

Osteoporosis and Fractures: The majority of people with SCI develop osteoporosis. In people without SCI, the bones are kept strong through regular muscle activity or by bearing weight. When muscle activity is decreased or eliminated and the legs no longer bear the body's weight, they begin to lose calcium and phosphorus and become weak and brittle. It generally takes some time for osteoporosis to occur. In people who use standing frames or braces, osteoporosis is less of a problem. Generally, though, 2-t years following SCI some degree of bone loss will occur.

  Using the legs to provide support in transfering is helpful in increasing the load on the bones, which may reduce or slow down the osteoporotic process. Standing using a standing frame or a standing table also helps prevent weakening of the bones and so does using braces for functional or parallel bar walking. Newer techniques, such as electrical stimulation of the leg muscles, may decrease osteoporosis as wel.

  Unfortunately, at the present time, there is no way to reverse osteoporosis once it has occurred. The main risk of osteoporosis is fracture. Once the bones become brittle, they fracture easily. An osteoporotic bone takes much longer to heal.

Pneumonia, Atelectasis, Aspiration: Patients with spinal cord injuries above the T4 level of injury are at risk to develop restriction in respiratory function, termed restrictive lung disease. This occurs five to 10 years following spinal cord injury and can be progressive in nature. The quadriplegic individual as part of a health care maintenance routine should have pulmonary function studies at yearly or every-other-year intervals between five and 10 years post injury. As the medical treatment of spinal cord-injured individuals continues to improve, respiratory complications of SCI are becoming more prominent. Adequate health maintenance and protection from this complication are appropriate and necessary as part of the long-term care of the spinal cord-injured individual.

Heterotopic Ossification: Heterotopic ossification is a condition not well understood that occurs in acute spinal cord injury and consists of the laying down of bone outside the normal skeleton, usually occurring at large joints such as the hips or knees. The primary problem with heterotopic ossification, or HO, is the risk for joint stiffening and fusion. Should the hip or knee become fused in a certain position, a surgical release is necessary to allow range of motion to occur. Unfortunately, it takes between 12 and 18 months for heterotopic bone to mature once it has developed. Activities that are used to prevent the development of HO include range of motion programs and other functional activities that move the joints within a functional range. Currently treatment is limited with the exception of preventing the joint fusion (termed ankylosis).

Spasticity: After spinal cord injury the nerve cells below the level of injury become disconnected from the brain. Following the period of spinal shock changes occur in the nerve cells that control muscle activity. Spasticity is an exaggeration of the normal reflexes that occur when the body is stimulated in certain ways. After spinal cord injury, when nerves below the injury become disconnected from those above, these responses become exaggerated.

  Muscle spasms, or spasticity, can occur any time the body is stimulated below the injury. This is particularly noticeable when muscles are stretched or when there is something irritating the body below the injury. Pain, stretch, or other sensations from the body are transmitted to the spinal cord. Because of the disconnection, these sensations will cause the muscles to contract or spasm.

  Almost anything can trigger spasticity. Some things, however, can make spasticity more of a problem. A bladder infection or kidney infection will often cause spasticity to increase a great deal. A skin breakdown will also increase spasms. In a person who does not perform regular range of motion exercises, muscles and joints become less flexible and almost any minor stimulation can cause severe spasticity.

  Some spasticity may always be present. The best way to manage or reduce excessive spasms is to perform a daily range of motion exercise program. Avoiding situations such as bladder infections, skin breakdowns, or injuries to the feet and legs will also reduce spasticity. There are three primary medications used to treat spasticity, baclofen, Valium, and Dantrium. All have some side effects and do not completely eliminate spasticity.

  There are some benefits to spasticity. It can serve as a warning mechanism to identify pain or problems in areas where there is no sensation. Many people know when a urinary tract infection is coming on by the increase in muscle spasms. Spasticity also helps to maintain muscle size and bone strength. It does not replace walking, but it does hlep to some degree in preventing osteoporosis. Spasticity helps maintain circulation in the legs and can be used to improve certain functional activities such as performing transfers or walking with braces. For these reasons, treatment is usually started only when spasticity interferes with sleep or limits an individual's functional capacity

Autonomic dysreflexia: Autonomic dysreflexia (AD) is a condition that can occur in anyone who has a spinal cord injury at or above the T6 level. It is related to disconnections between the body below the injury and the control mechanisms for blood pressure and heart function. It causes the blood pressure to rise to potentially dangerous levels.

  AD can be caused by a number of things. The most common causes are a full bladder, bladder infection, severe constipation, or pressure sores. Anything that would normally cause pain or discomfort below the level of the spinal cord injury can trigger dysreflexia. AD can occur during medical tests or procedures and need to be watched for.

  The symptoms that occur with AD are directly related to the types of responses that happen in the sympathetic and parasympathetic nervous systems. Symptoms such as a pounding headache, spots before the eyes, or blurred vision are thee direct result of the high blood pressure that occurs when blood vessels below the injury constrict. The body responds by dilating blood vessels above the injury, causing flushing of the skin, sweating, and occasionally goosebumps. Some patients describe nasal stuffiness and will feel very anxious. Uncontrolled AD can cause a stroke if not treated.

  The treatment for AD involves removing the reason for the stimulation. One of the first things a patient can do is to sit up. This naturally decreases blood prsessure. If there is a catheter in place, it should be checked to be certain that there is not a kink in the tubing. If there is not a catheter in place, the patient should be catheterized. The bowels should be checked to be ceratin there is no stool in the rectum. If the symptoms are caused by skin breakdown, the patient should get to an emergency department as soon as possible.

  The primary risk of AD is stroke. It is a potentially life-threatening condition. If AD is left untreated, the body's attempt to control blood pressure will severely decrease the heart rate. This, combined with uncontrolled high blood pressure, can be fatal. For this reason, it is very important to treat this condition as soon as possible. The most important thing patients can do to prevent AD from occurring is to take good care of themselves. Patients should monitor bladder output (also see bladder care and management) and should maintain a regular bowel program which fully empties the bowels. They should also do regular skin checks to prevent pressure sores from occurring.

 The Paralyzed Veterans of America has put together a more detailed, in depth guide to AD that you can download here and view in your browser.

 (The guide requires Adobe Acrobat 3.0 or later if you have trouble viewing the guide download the latest version here)

Deep vein thrombosis: (DVT) or pulmonary embolism is a potentially severe complication of spinal cord injury. As mentioned above, there are changes in the normal neurologic control of the blood vessels that can result in stasis or "sludging". Deep vein thrombosis in the lower leg is almost universal during the early phases of recovery and rehabilitation. Thromboses in the thigh, however, are a great concern, as they are at risk for becoming dislodged and passing through the vascular tree to the lungs. A major obstruction of the arteries leading to the lung can potentially be fatal. Therapeutic measures to reduce or eliminate the risk for deep vein thrombosis include Ace wrapping of the legs and the use of pneumatic compression stockings. Medications administered subcutaneously, such as heparin, are useful in reducing blood viscosity and improving flow. In the event that a thrombosis develops, treatment is begun with intravenous heparin. Once adequate anticoagulation is provided, the patient is switched to or medication, called Coumadin

Cardiovascular disease: Cardiovascular disease is a major long-term risk of spinal cord injury. SCI individuals live in general rather sedentary lives and are at higher risk for cardiovascular disease than the able-bodied population. Therefore, careful assessment of cardiovascular function and the encouragement of exercise programs are appropriate and necessary long-term aspects of spinal cord injury management and care. The prescription of upper extremity exercise programs in spinal cord-injured individuals are similar to those used in other populations with the exception of the use of adaptive equipment such as racing wheelchairs or monoskis.

Syringomyelia- A post-traumatic enlargement of the central canal of the spinal cord is termed syringomyelia. It occurs in approximately 1-3% of all spinal cord-injured individuals. The primary risk of syringomyelia is a loss of function above the level of the original spinal cord injury. For example, in a patient with a thoracic-level spinal cord injury may complain to his or her physician of numbness and weakness involving the extremities. The condition will progress with time and needs to be treated aggressively through surgical drainage. Often patients with early evidence of a syrinx will be followed to evaluate the progression of the condition. Significant syringomyelia is treated with surgical decompression and the placement of a drainage tube into the spinal cord.

Neuropathic/Spinal Cord Pain- Neuropathic (nerve-generated) pain is a significant problem in some spinal cord-injured patients. Varying types of pain are described in spinal cord injury. Damage to the spine and soft tissues surrounding the spine can cause aching at the left of the injury. Nerve root pain is described as sharp or may be described as having an electric shock-type quality. Occasionally SCI patients will describe phantom limb pain or pain that radiates from the level of the lesion in a specific pattern that is related to injury or dysfunction at the nerve root or spinal cord level. Various medications and nerve block procedures have been described and are of some use in the treatment of neuropathic pain following spinal cord injury.

Respiratory Dysfunction- Respiratory complications and infection predominate as post-SCI complications. When the injury involves the upper thorax, the normal breathing pattern is permanently altered. The diaphragm does most of the work in quiet breathing. The chest wall muscles (intercostals) are used primarily for deep breathing or coughing. The abdominal muscles also participate in coughing. When the intercostal and abdominal muscles are paralyzed, the entire load is taken by the diaphragm. This results in poor coughing and a high risk of pneumonia. Pneumonia is one of the most common complications of acute spinal cord injury. Preventive measures are very important to reduce the risk of pneumonia. These include: percussion and drainage using gravity to assist; assisted coughing (also termed "quad" coughing); abdominal binders (to increase the resistance against which the diaphragm works); and early mobilization (i.e.; getting the patient out of bed as soon as possible)

Spinal Stenosis: introduction

The spinal canal is like a tunnel which runs up and down the human spine. This canal sits directly behind the bony blocks which make up the spine (vertebrae) and contains the nerves (spinal cord and nerve roots) running from the brain to all areas of the body

When something causes a narrowing of this canal then the nerves can become irritated or squeezed. This can lead to a variety of symptoms ranging from tingling, numbness, and weakness to severe pain and paralysis. Common conditions which can narrow the spinal canal include a herniated disc (often called a slipped disc), fracture of the spine, tumor, infection and degeneration. A set of symptoms related to narrowing of the spinal canal seen with aging and degeneration is called spinal stenosis. The symptoms of spinal stenosis most commonly include a sensation of heaviness, weakness and pain with walking or prolonged standing. At rest these symptoms usually disappear. These symptoms are related to the irritation of the nerves in the spinal canal which is worsened with standing or walking due to mechanical compression or stretching of the nerves. Patients often complain of a gradual decrease in their ability to walk, requiring more frequent stops to rest their legs. The treatment for spinal stenosis is dependant on the severity of symptoms. Generally, aerobic activities like walking combined with a guided exercise program and weight loss (in overweight patients) is recommended first.
 
When there is no relief, some specialists recommend injection treatments although the effectiveness of this is limited. Surgery is indicated when symptoms are severe, progressive and a specific area of narrowing in the spinal canal has been discovered. The surgical procedure is aimed at freeing up the nerves in the canal by removing pieces of bone and thickened tissues such as the ligaments. A spinal fusion may also be necessary to stabilize the spine

 Explanation:

The spine consists of a series of bone blocks (vertebral bodies) which are separated from one another by discs of soft tissue. Within the structure of the spine sits a tunnel called the spinal canal. This tunnel contains the neurologic structures including the spinal cord and nerve roots. Although there is some free space between the neurologic structures and the edges of the spinal canal, this space can be reduced by many different conditions including injury to the spine. The canal is surrounded by bone and ligaments and therefore can not expand if the spinal cord or nerves require more room. Therefore, if anything begins to narrow the spinal canal, there is risk for irritation or injury of the spinal cord or nerves. Conditions which can lead to narrowing of the spinal canal include infection, tumors, trauma, herniated disc, arthritis and degeneration.

Spinal stenosis refers to the condition of neurologic problems associated with narrowing of the spinal canal due to degenerative changes in the spine. Arthritis of the small joints in the spine (facets) as well as thickening of ligaments and formation of bony spurs can all lead to gradual squeezing and irritation of neurologic structures. This process is usually gradual and can lead to symptoms such as pain with walking, a decreased endurance for physical activities, heaviness in the legs, tingling sensations, tightness and numbness in the legs with activity, and often associated low back pains.

Treatment for spinal stenosis ranges from physical therapy to epidural injections and finally surgery in certain cases. Since patients affected by spinal stenosis are usually elderly, treatment must carefully consider not only the disease in the spine but also the risks and benefits of treatment in each individual. Although therapy and steroid injections into the affected area of the spine can offer good relief in some patients, there are people who will only get temporary relief if at all. In patients who have failed non-operative treatment, surgery can sometimes be considered. Prior to designing a treatment plan for any individual, careful diagnosis must be made. This will often involve tests such as an MRI, CT scan, or myelogram and plain X-rays. In those patients who are candidates for surgery, the goal is to free up the constricted regions of the spinal canal to ensure freeing the affected neurologic structures. Occasionally, in order to stabilize a degenerated part of the spine, a fusion will be performed. This involves laying down of bone over an area of the spine so that a solid block is created where there was previously arthritis with pain and an unstable spine.

Surgery for spinal stenosis has a high success rate in patients carefully selected for this procedure. It remains a useful approach in treatment when other options have been exhausted and after careful review of risks and benefits with the patient.