(1) Viral encephalitis. Although arboviruses from mosquitoes, birds, or
small rodents are the principal vectors, there are many other viruses that may produce
encephalitis. The "masslike" lesions in the temporal lobes are caused by herpes
simplex. The mumps virus, other enteroviruses, or poliovirus can be the cause of
encephalitis. It is also produced by the rabies virus.
(2) Erythematous diseases. Erythematous diseases of childhood (measles,
rubella, infectious mononucleosis, and varicella) may be accompanied by encephalitis.
(3) Result of vaccination. After the use of certain immunizing agents,
encephalitis may occur. The vaccines to prevent pertussis, smallpox, and rabies are
included in this group.
(4) Toxic encephalitis. This type may result from bacterial toxins, poisons,
or drugs. It can be clinically indistinguishable from infectious encephalitis.
(5) Reyes' syndrome. This is a rare but severe complication of influenza or
from other diseases such as parainfluenza virus, echovirus, or coxsackievirus. There is
a rapid development of hepatic failure and encephalopathy. Reyes' Syndrome has a 30
percent fatality rate.
(a) Signs and symptoms. The victim of encephalitis has fever, sore
throat, nausea, vomiting, malaise, stupor, lethargy, coma, and convulsions. The signs
of encephalitis include tremors, convulsions, stiff neck, cranial nerve palsies, meningeal
irritation, paralysis of extremities, absent superficial reflexes, pathologic reflexes, and
exaggerated deep reflexes.
(b) Treatment. A variety of procedures may ensure a successful
outcome although specific therapy is not available. The reduction of intracranial
pressure (by using mannitol or a urea), con-trolling convulsions, administration of
oxygen, maintenance of the airway, and providing adequate nutrition during prolonged
coma are measures that have proven to be effective. The conventional IV nutrition may
continue for 72 hours, but must be replaced by a nasogastric tub or intestinal feedings.
It is important to begin treatment early for prevention of decubiti, urinary tract infection,
and pneumonia. If necessary, administer anticonvulsants.