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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.
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.
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. 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: 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.
Bony 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, so 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.
Spinal Stenosis: 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. |
