Poliomyelitis

Poliomyelitis ("polio"), or infantile paralysis, is a viral paralytic disease. The causative agent, a virus called poliovirus (PV), enters the body orally, infecting the intestinal lining. It may proceed to the blood stream and into the central nervous system causing muscle weakness and often paralysis.

Types of polio

Non-paralytic polio

Non-paralytic polio will result in fever, vomiting, abdominal pain, lethargy, and irritability. Some muscle spasms in the neck and back, with muscles generally tender to the touch.

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Spinal paralytic polio

This strain of the poliovirus attacks the spinal column where it destroys the anterior horn cells which control movement of the trunk and limb muscles. Although this strain of the poliovirus can lead to permanent paralysis, less than one in two hundred with symptoms will result in paralysis. The most common paralysis will affect the legs. Once the poliovirus invades the intestines, it is absorbed by the capillaries in the walls of the intestine and is then carried by the bloodstream throughout the body. The poliovirus attacks the spinal column and the motor neurons—which control physical movement. It is during this period of infection that flu-like symptoms occur; however, for people who have no immunity or have not been vaccinated, the virus usually goes on to infect the entire spinal column and the brain stem. This infection affects the central nervous system (CNS)—spreading along nerve fibers. As the virus continues to multiply in the CNS, the virus destroys motor neurons. Motor neurons do not regenerate and any affected muscles will no longer respond to CNS commands. The most common paralysis occurs to the muscles of the legs. The result is that the limb becomes floppy and lifeless—a condition known as acute flaccid paralysis (AFP). An extreme infection of the CNS can cause extensive paralysis of the trunk and muscles of the thorax and abdomen (quadriplegia).

Related Topics:
Motor neurons - Spinal column - Brain stem - Acute flaccid paralysis - Quadriplegia

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Bulbar polio

Bulbar polio is thought to be the result of a person having no natural resistance to the polio virus, the result being that the brain stem is allowed to be attacked. The brain stem contains the motor neurons that control breathing and the cranial nerves, which signal the various muscles that control eyeball movements; the trigeminal nerve and facial nerve which innervate cheeks, tears, gums, and muscles of the face, etc; the auditory nerve which provides hearing; the glossopharyngeal nerve which in part controls swallowing and functions in the throat; tongue movement and taste; and the nerve that sends signals to the heart, intestines, respiratory (lungs) and the accessory nerve that controls upper neck movement. Thus bulbar polio could affect any or all of these functions.

Related Topics:
Bulbar polio - Cranial nerves - Glossopharyngeal nerve

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Without respiratory support, bulbar polio usually results in death. Of those who become infected, five to ten percent will die when their breathing muscles become immobilized. Death usually occurs after damage to the cranial nerve responsible for sending the signal to breathe to the lungs. Bulbar victims may also die from damage to the swallowing function; a victim can drown in their own secretions unless adequately suctioned, or given a tracheostomy to suction secretions before the liquid enters the lungs. It is difficult to have a tracheostomy and still be able to tolerate the airtight collar of an iron lung. There may also be an overwhelming invasion of the virus into other parts of the brain causing coma and death.

Related Topics:
Tracheostomy - Iron lung - Coma

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The mortality rate of bulbar polio ranges from twenty-five to seventy-five percent, with the variable being the age of the person. To this day there are still polio survivors who must spend their entire day or most of their day in an iron lung or attached to an assistive respiratory machine to stay alive. Bulbar polio and spinal polio often coexist. They are both a subclass of paralytic polio. Paralytic polio is not necessarily permanent. One can have had paralytic polio and recover seemingly normal function.

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