Acute poliomyelitis is a highly contagious viral disease which ranges in severity from inapparent infection to overwhelming paralytic illness and death. The virus is spread by human contact and enters through the nose or mouth, then spreading to various parts of the body.
Poliomyelitis is particularly liable to affect certain parts of the spinal cord, the brain proper and the connection between the brain and the spinal cord (brainstem). It is when the virus affects the brainstem that bulbar poliomyelitis ensues. Bulbar poliomyelitis is usually associated with the other forms of polio such as involvement of the spinal cord leading to arm or leg weakness or paralysis.
The brainstem contains the cranial nerves; related to the functions of seeing, eye movements, clenching the jaw, facial movements, hearing, swallowing, and speech and tongue movement. One cranial nerve, the vagus, is also associated with many other body functions such as heart rate, blood pressure, bladder emptying, production of normal salivary and lung secretions and normal bowel functions.
Also in the brainstem is the respiratory center which controls breathing and, if this is affected, progressive slowing and irregularity of the respiratory rhythm may become apparent (respiratory failure).
Common signs
When the polio virus affects the brainstem, any or all of the cranial nerves may become paralyzed, resulting in a disruption of the body function associated with the particular cranial nerves or nerves involved. The most common signs seen in bulbar poliomyelitis are paralysis of swallowing and paralysis of the vocal cords. The condition may be so severe that voice sounds are limited to hoarse cries. Involvement of the eye movement nerves may lead to transient or permanent squints. Forced clenching and later, paralysis is usually restricted to one or more muscles, leading to assymetrical facial expression.
Complications
If the vagus nerve is involved, many other serious complications may occur. Vomiting and constipation are almost invariable during the acute illness and for several weeks thereafter. Other complications include bladder paralysis and the inability to pass urine; excess salivary and lungs secretions leading to difficulty in breathing; and excessive increase in heart rate and blood pressure leading to various irregularities in heart functions.
When bulbar poliomyelitis is the first manifestation of poliomyelitis, it its a dangerous sign, for the progress of paralysis usually continues for four to five days. Associated with various body dysfunctions, agitation and fear may become pronounced. Delirium is prone to occur at night. Very severe bulbar poliomyelitis can produce a state of stupor or acute excitement.
Treatment
There is no specific treatment for the poliomyelitis viral infection but patients must be hospitalized to deal with all the complications. For instance, paralysis of swallowing is treated by withholding oral intake and posturing the patient so that he does not choke on his own secretions; respiratory failures is treated by the early and effective use of an artificial respirator; irregular heart functions and irregular blood pressure are treated with various drugs; acute urinary retention is alleviated by the insertion of a flexible tube (catheter) into the bladder.
Recovery rate
At the peak of the acute illness, usually lasting 4-7 days, it is impossible to predict accurately how much recovery will take place. Less than 10 percent of patient dies when treated with up-to-date methods. Generally, those muscle groups and bodily functions which work partially at the end of the acute illness will recover considerably. On the other hand, muscles which show no voluntary motion regain functional usefulness.
The incidence of poliomyelitis has dropped remarkably, especially in Western countries, following widespread immunization against the disease with oral vaccines. Nevertheless, low immunization rates still prevail in certain disadvantaged population groups and underdeveloped countries, and these represent the principal population at future risk of paralytic disease.
Source:
poliomyelitis, Infoplease.com
Poliomyelitis, patient.co.uk
Polio Website, Brown University
