Causes

MOVEMENT DISORDERS IN SPINAL CORD INJURY: CAUSES

The Spinal Cord is like a great telephone communication system. It is made up of nerves, which carry messages between the brain and all other parts of the body. The spinal cord is an extension of the brain. It is enclosed within the spinal column, which is made up of irregularly shaped rings of bone called vertebrae.

Many nerves lead from the brain through the spinal cord to the skin, muscles, and organs of the body, such as the lungs, bladder, and stomach. They are called peripheral nerves because they travel to the skin, muscles, and organs and cause motion in these body parts. Other nerves lead in the opposite direction, from the surface of the body and organs inside, through the spinal cord, to the brain. These nerves are called sensory nerves because they "sense" and relay information to the brain about heat, cold, pressure, pain, and position.

There are a total of 31 pairs of spinal nerves that branch out to all parts of the body. Each pair has a motor and sensory nerve. All spinal nerves branch out and divide into peripheral nerves, which reach every inch of your skin, every muscle, every blood vessel, every bone - every part of your body from head to toe - in a type of web.

All nerves operate along a pathway. When the pathway is broken, messages from and to the brain are not delivered. This is what happens when there is an injury to or disease of the spinal cord. An injured spinal cord is like a broken telephone cable. The telephone on each end of the cable is OK -- just like the brain and body parts on each end of the nerves that run through the spinal column are OK -- but the connection is broken. The result is paralysis and a lack of sensation. SCI affects each person differently because the spinal cord is usually not damaged in exactly the same way in any two individuals.

Following is an illustration of the different sections of the spinal cord: neck, chest, lower back, and tailbone. The vertebrae, or rings of bone, are used to name the different sections. Also shown are the spinal nerves in each section of the spinal cord that cause motion in all body parts and relay sensation information to the brain from all body parts.

Spinal Cord Sections, Vertebrae, and Spinal Nerves

Spinal Cord Sections, Vertebrae, and Spinal Nerves

Depending on where the spinal cord is injured, a person will either have weakness or paralysis to some degree in the lower body and legs (paraplegia), or, weakness or paralysis to some degree in all legs and arms (tetraplegia). An injury at a particular vertebra will affect all the nerves below the injury. For example, if you are injured at the C5 or C6 level -- at the level of the 5th or 6th cervical vertebrae in the area of the neck -- the nerves in the spinal cord below those vertebrae will be affected, and the injury will involve weakness in shoulder and arm muscles, as well as body and leg muscles (tetraplegia). If you are injured at the T10 level -- i.e. at the level of the 10th thoracic vertebra near the lower back -- the injury will not affect your arms and shoulders, but it will affect your body, abdomen, and leg muscles (paraplegia).

Doctor's refer to your injury based on where the bones and nervous system were damaged. The nerve tissue of the spinal cord in an adult is shorter than the bony spinal column. Below the neck region, the bony level (e.g. T9) would actually correspond to a lower neurological level (T10). Your diagnosis is based on the two things: the level of the injury to the spinal cord and the level of the fracture in the spinal column. The numbers of the two levels may be slightly different. The level of the injury to the spinal cord refers to the spinal nerves that still have function. SCI can be "complete" or "incomplete". In complete SCI, there is no voluntary movement or sensation below the level of injury. In incomplete SCI, there is some sparing of sensation or voluntary movement below the level of injury. Following is information from the "Sharp Functional Outcome Scale" which provides a framework for long-term functions after spinal cord injury.