Causes

MEDICAL PROBLEMS IN SPINAL CORD INJURY: CAUSES

As you have seen in the previous section, SCI affects the spinal nerves and the peripheral nerves of the body's central nervous system, that controls voluntary movement and sensation. Depending on the level of the spinal cord injury, there may be paralysis of the skeletal muscles; loss of sensation, such as sense of touch, pain, temperature, pressure; and changes in breathing pattern and capacity as a result. SCI also affects the body's autonomic nervous system, which controls the involuntary functions of internal organs and glands. The autonomic nervous system operates day and night, without any awareness or conscious control on your part. Depending on the SCI, there may be changes in pulse, blood pressure, body temperature, perspiration, bladder and bowel function, glandular secretions, and sexual function.

There are two divisions of the autonomic nervous system -- the sympathetic and the parasympathetic -- which regulate involuntary functions. While the two divisions have opposing effects, they normally balance each other. One system predominates in certain situations, and the other predominates in other situations depending on the body's needs.

The sympathetic nervous system supplies energy for sudden responses, such as fear. It prepares you for immediate action. Your blood pressure goes up, your heart beats faster, and your pupils get larger. The parasympathetic nervous system supplies a slowing down action. It keeps your body on an "even keel", preventing it from becoming over excited and enabling it to function properly at all times. Through the parasympathetic nervous system, your blood pressure is lowered, your heart beats more slowly, and the size of your pupils decreases.

SCI also interrupts the autonomic nervous system, and the brain can no longer regulate the functions of this system and maintain the balance of the opposing sympathetic and parasympathetic divisions. This can result in changes in blood pressure, changes in the body's temperature control system, and changes in the functioning of the digestive tract, the sex organs, or the bladder. In paraplegia (the weakening of the legs and lower body) the lower parasympathetic system is interrupted. In tetraplegia (the weakening of the legs and the arms) the entire sympathetic system is interrupted.