Structure of the spine
Some understanding of the structure of the spine (spinal column) and the spinal cord is important as it helps your Neurosurgeon explain about the part of the spine that is injured and also the parts of the body that is going to be affected as a result of the injury to the spinal cord and nerves in that area.
The spine (in layman’s terms the back bone) is made up of blocks of bone called the vertebrae (single = vertebra) or vertebral bodies which sit one on top of another and are linked to one another much like a bicycle chain by the disk in front and various sets of ligaments from behind. As they have a hole in the center (spinal canal), when stacked together, they completely surround the spinal cord which is the tube of nervous tissue that carries the signals and messages from the brain to the rest of the body such as the muscles in the arms and legs to make them work. The nerves are the branches (much like branches of a Christmas tree) which come out from the spinal cord at each vertebral level. They travel out on each side and exit the spinal column via holes in between the stacked vertebral bodies called the inter-vertebral foramen.
Figure I shows how the spinal cord travels through the spinal canal in the spine. It is
covered by a fairly thick protective membrane called the
dura mater (which also covers the brain ) as it lies in the spinal canal. The nerves which supplies the muscles exit the spinal column via the inter –vertebral foramen
Structurally the spinal column can be divided into 5 parts. See Figure II
1) Cervical (neck) part: made up of 7 vertebral bodies. Traditionally named C1 to C7
2) Thoracic (dorsal) part: made up of 12 vertebral bodies. This part of the spine is at
back the upper body. T1 to T12
3) Lumbar (lower back) part: made up of 5 vertebral bodies. L1 to L5
4) Sacral (lower most or buttock) part: made of 5 vertebral bodies. S1 to S5 but
these bodies are fused into one piece called the sacrum. This is the that part lies in
between the hip-bones.
5) The coccyx (tail bone) is a very small piece right at the bottom end .
The spinal column provides support for the body as well as protection for the spinal cord
that travels in it.
An injury to the spine thus not only AFFECTS STABILITY of the body but may also
cause PAIN , NUMBNESS and PARALYSIS and other problems such as difficulty with
urination and bowel control because of the associated injury to the spinal cord and nerves
arising at the injury level and often everything below that as well. The level of spinal
cord injury and nerve injury can thus be described by the level of the vertebral body /
level injured e.g. C4/5 fracture , T10/11 injury etc.
Some statistics of interest
There are about 12 to 53 new spinal injuries per million population in the developed countries every year. In the United States, at any one time there are 721 to 906 people with spinal cord injury per million population. The incidence (new spinal cord injuries) is expected to be much higher in our country for example, in the Neurosurgical service in Sarawak General Hospital, there is a case of spine injury every month for patients admitted with head injury.
There are more men injured compared to women in a ratio of 3.4:1. Typically these patients are young and two thirds of these occur in individuals less than 30 years of age.
Motor vehicle accidents account for more than half of the spinal injury cases around the world. This however will vary from country to country.
Twenty to 57 percent of people with spinal cord injury also have significant injuries elsewhere. Up to ten percent of spinal injury patients can have associated head injuries and about a quarter to half of head injury patients have a spinal cord injury.
What happens during an injury to the spine.
The damage to the spinal cord can be divided into what happens at the time of the accident(primary injury) and what happens after the initial impact (secondary injury).
Primary injury as its name implies is something that can only be prevented. This will involve precautions taken while driving, in work and in recreational activity. People on motorbikes are particularly vulnerable as in a fall from a motorcycle there is little or no protection to the neck. A helmet helps to protect the head but not the spine.
After the initial trauma or injury, secondary injury may occur that makes the effects of the primary injury worse. It is very important to stabilize (splint) the spine to prevent further injury to the spinal cord as a result of movement and further spinal cord compression. A person with a suspected spinal injury should be moved only on a spinal board which is a piece of hard board where the patient is made to lie and strapped down for transport. The neck should also be supported in a hard collar to prevent movement of the cervical spine which is often the most mobile part of the spine. Attention is also given to the airway, breathing and the blood pressure of the injured person to ensure adequate delivery of oxygen and other nutrients to the spinal cord.
In secondary injury, at a cellular level, there occurs a series of destructive chemical reactions that happening within the substance of the spinal cord that leads to further damage such as the production of “bad”molecules (free radicals) that attack the cell wall of the nerve cells leading to swelling, leakiness of the cells and finally cell death. Drug therapy is thought have some role in the treatment to reduce the impact of this secondary ongoing destructive process.
Clinical symptom and sign
A patient with a spine injury may only have pain. Others have weakness or numbness.
Some names that a Neurosurgeon may use to describe the effects of the injury:
1) Paraplegia: BOTH LEGS are paralysed
2) Quadriplegia: ALL FOUR LIMBS i.e. arms and legs are paralysed “neck down”
3) Complete vs Incomplete injury: A complete injury happens when there is no motor or sensory function at and below the level of injury. An Incomplete injury is one where there is still some function such as partial weakness or sensation below the level of injury.
Paraplegia occurs if the damage to the spinal cord is at the thoracic level and below.
Quadriplegia occurs if the damage is level of the cervical spine.
Other functions that may be affected or lost include the loss of the different types of sensations such as pain, temperature and touch, the ability to feel the position of the limbs, problems of urination, bowel movement and sexual dysfunction.
As a spinal cord injury has such devastating consequences, it is very important to suspect spinal injury particularly in patients who have suffered multiple trauma, falls from a height and those who complain of pain along their spine.
Imaging i.e. getting X-rays and scans (especially MRI scans) are very useful and helpful in proving spinal injury as well as to the show the level and severity of the injury. It adds further information to the clinical picture that the Neurosurgeon obtains through a physical examination to help the Neurosurgeon decide what best to do in a particular situation.
Not all spine injuries show up on the x-ray. In children particularly, there can be spinal cord injury without any fracture of the bone being seen (called spinal cord injury without radiological abnormality or “SCIWORA” in short). This is due to the soft ligaments in necks of the children. Here an MRI scan would be more useful to show the injury to the spinal cord.
Many times X-rays may have to be supplemented with CT scans or MRI scans particularly if a fracture or dislocation is seen. The reasons for doing both types of scans is that the CT scan is very good to show bony damage and the MRI scan is good for showing soft tissue injury such as the spinal cord and ligaments as well as any bleeding.
This begins at the accident scene itself. Helpers take care to protect the injured person’s spine by putting them on a spine board and putting on a cervical collar. Movement should be in an “en-bloc” fashion i.e. the injured person is moved “in one piece” until he can be secured onto a spinal board and collar. If one is unsure how to do this or if there is insufficient help available, it may be better to wait for more and better equipped help to arrive.
The airway, breathing, blood pressure must be checked and maintained at all times. Oxygen may be given as necessary. This may involve putting on an oxygen mask or inserting a tube called an endotracheal tube into the wind-pipe to deliver oxygen directly to the lungs. If the breathing is poor or the person has difficulty with his breathing then the person may need to be connected to a ventilator (breathing machine).
A steroid drug called Methylprednisolone may be given in very high doses if the injury to the spinal cord occurs within 8 hours of the injury to try and prevent or reduce the effects of secondary spinal cord injury. However this is not regarded as standard treatment in all places. This medication is usually given in a hospital setting in the Intensive Care Unit.
The next stage is to stabilize the fractured or dislocated of the spine. The spine needs to be realigned if this has been distorted and the spinal canal relieved of any compression or narrowing particularly if there is any pressure on the spinal cord from the bones or surrounding soft tissue. This may involve traction (gradual stretching and realignment of the dislocated or distorted spinal column with graded weights ) of the cervical spine. This may then followed by an operation to either reduce the fracture or dislocation if the traction fails and also to fix and fuse the spine using screws and plates or rods. Usually, fusion with bone graft is done at the same time and this can be by using the patient’s own bone (usually from the hip- an autograft) or occasionally from donor bone ( stored or cadaveric bone - an allograft) or even artificial bone made from ceramics, although these are thought to have poorer fusion rates than using the patient’s own bone.
Previously it has been recommended to do such operations later when the patient has been well stabilized but recently there is some evidence to suggest that operating early may be better or at least not as dangerous and detrimental as previously thought. It is best left to the Neurosurgeon concerned as to the most appropriate timing for the individual patient, depending on the patient’s condition and severity of his injuries as well as the Neurosurgeon’s personal expertise and experience.
After surgery, the patient will require a prolonged period of Rehabilitation through physiotherapy, occupational therapy and other forms of rehabilitation including help to deal with the many psychosocial issues that arise as a result. These patients need to have care to prevent pressure (bed) sores, catheterization of the bladder (tubes in the bladder to drain the urine) and education for the use of the wheelchair, if appropriate. The care giver will also need to be educated and supported with regards to how he or she may care for their injured loved ones.
Some homes may need to be modified as best as possible to ensure that the injured person has reasonable access to his or her home facilities with as little disruption to the others in the home.
The injured person’s outcome depends on a number of factors such as
1) Age: Generally, the older the patient the poorer the outcome.
2) Neurological grade: The more severe the degree of loss of neurologic function,
the poorer the outcome. Complete injuries fare worse than incomplete injuries.
3) Levels of injury: the higher the level the poorer the outcome e.g. an injury at the C1 to C3 level has more than 6 times the chance of dying from the injury than one below that level.
These patients usually need prolonged stay in a hospital setting with an average of 171 days of hospital-stay over a 2-year period.
The chance of dying from a spinal injury range from 48 to 79 percent at the time of accident or on arrival to the hospital. Death after admission to hospital range from 4.4 to 16.7 percent. The cause of death is usually pneumonia and renal failure.
With a good program for prevention, good management at the scene, at the hospital and after hospitalization, spinal injury outcomes can be improved. A lot of research into spinal cord injury is currently being carried out in various parts of the world.
Importantly, acceptance and recognition of the existence and rights of these individuals by society and civic planners will help to give hope to these unfortunate people who suffer from these devastating injuries.
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