Spinal-Injury.net :  What is Spinal Cord Injury?


What is Spinal Cord Injury

Spinal Cord Injury has many causes and the resulting disability can take many forms.  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, sports accidents, falls, etc.) or disease (polio, spina bifida, spinal tumours, etc.). The spinal cord does not have to be severed in order for a loss of function 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 other back injuries such as ruptured disks, or pinched nerves, or even broken vertebrae.

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. Whilst recovery from broken bones is not without complications, if the spinal cord wasn't compromised at the time of injury then with the right post injury treatment there should be a full recovery. 

If you have broken your neck or your back and not affected the spinal cord then you are extremely fortunate.  Damage to the spinal cord and the resultant loss of function is usually permanent and will mean a varying degree of 'lifelong' disability dependant on where and how seriously the cord was affected.   All too often everyone who has broken their neck or back are thought of in the same category and recoveries are often compared.  It comes down the the single fact that if the spinal cord has been damaged in any way, the outcome of the injury / illness will be a lot different to someone has just broken vertebrae.  The late Barry Sheene, a British motorcyclist broke virtually every vertebrae in his neck and back during his career.  Somehow he managed to get away without damaging his spinal cord on any occasion and made a full neurological recovery from his injuries i.e. No permanent loss of movement or body functioning.  Someone else may have a far more trivial accident and remain completely paralysed because of damage sustained to the spinal cord. 

The spinal cord is the largest nerve in the body and an extension of the brain. Nerve fibers are responsible for the communication systems of the body -- sensory, motor and autonomic functions. All the information going from the brain to the limbs travels through the spinal cord.

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 tetraplegia or 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 does the Spinal Cord do?

The spinal cord is about 18 inches long. It starts at the base of the brain, and extends to about the waist. Because the spinal cord is such an important part of the nervous system, it is surrounded and protected by bones called vertebrae. The spinal cord is the first relay station for sensory information on its way to the various centres of the brain. The spinal cord has many fibers that carry these messages between the brain and different parts of the body. The messages may:

tell a body part to move; send and receive messages of sensation from the body, such as pain, heat, or cold; or control the involuntary activities of the body, such as body temperature.

Damage to the spinal cord can occur from a traumatic injury. The backbone may pinch the spinal cord, causing it to bruise or swell, or the injury may tear the spinal cord and its nerve fibers. After a spinal cord injury, all the nerves above the level of injury keep working like they always have. However, at the point of injury and below, the spinal cord nerves cannot send messages between the brain and parts of the body. Sensory functions, bladder functions, and movement are all dependent on information that travels up and down the spinal cord. Interruption of spinal cord function by a traumatic injury may result in a loss of feeling and motor function.

The anatomy of the spinal column is extremely well designed to serve many functions. All of the elements of the spinal column and vertebrae serve the purpose of protecting the spinal cord, which provides communication to the brain, mobility and sensation in the body through the complex interaction of bones, ligaments and muscle structures of the back and the nerves that surround it. The back is also the powerhouse for the entire body, supporting our trunks and making all of the movements of our head, arms, and legs possible.

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's carry messages about sensation from the skin and other body parts and organs to the brain. The motor portions of the LMN's 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.

Effects Of Spinal Cord Injury
There are two classifications of spinal cord injury tetraplegia (also called quadraplegia) and paraplegia.  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.  Most incomplete injuries are unique in presentation and eventual outcome (recovery).  Of course every individual case is treated on its merits.  See below for further categories of SCI.

Tetraplegia - Paraplegia - Complete SCI - Incomplete SCI - Treatment - Complications - Causes of SCI - My Injury

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Spinal-Injury.net :  What is Spinal Cord Injury?



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