Meningitis natural history


 * Associate Editor(s)-In-Chief:

Complications
In children there are several potential disabilities which result from damage to the nervous system. These include sensorineural hearing loss, epilepsy, diffuse brain swelling, hydrocephalus, cerebral vein thrombosis, intra cerebral bleeding and cerebral palsy. Acute neurological complications may lead to adverse consequences. In childhood acute bacterial meningitis deafness is the most common serious complication. Sensorineural hearing loss often develops during first few days of the illness as a result of inner ear dysfunction, but permanent deafness is rare and can be prevented by prompt treatment of meningitis.

Those contract the disease during neonatal period and those infected by S pneumoniae and gram negative bacilli are in greater risk of developing neurological, auditory, or intellectual impairments or functionally important behaviour or learning disorders which can manifest as poor school performance.

In adults central nervous system complications include cerebrovascular disease, brain swelling, hydrocephalus, intrcerebral bleeding; systemic complications are dominated by septic shock, adult respiratory distress syndrome and disseminated intravascular coagulation. Those who have underlying predisposing conditions e.g. head injury may develop recurrent meningitis. The case-fatality ratio is highest for gram-negative etiology and lowest for meningitis caused by H influenzae (also a gram negative bacili). Fatal outcome in patients over 60 years of age are more likely to be from systemic complications e.g. pneumonia, sepsis, cardio-respiratory failure; however in younger individuals it is usually associated with neurological complications. Age more than 60, low glasgow coma scale at presentation and seizure within 24 hours increase the risk of death among community acquired meningitis.

Prognosis
The overall mortality rate in Durand’s study was 25%
 * Three factors were associated with a significantly higher mortality:
 * Age > 60 (37% vs. 17%, p < 0.001, RR 2.1).
 * Obtunded mental status on admission (49% vs. 16%, p < 0.001, RR 3.0).
 * Onset of seizures within 48 hours of admission (72% vs. 18%, p < 0.001, RR 4.0).
 * 98% of the patients in this study who died had at least one of these three risk factors.