Current concepts of meningitis: Its etiological factors, management options and prognosis

Meningitis per se is a pathological process confined to the lepto-meninges without grossly affecting the brain, spinal cord. However, in complicated meningitis, there is involvement of the brain, spinal cord and or nerve roots also. The pathological process is an inflammatory and or allergic response of the meninges to a wide variety of etiological factors. The etiological spectrum of the meningitis has changed recently due to emergence of immuno-compromising diseases. The causative factors are mainly categorized in following groups: 1.Infections and infestations (viruses, bacteria, fungi, parasites); 2.Cancer cells 3.Foreign materials including blood, chemicals, drugs etc.4.Other causes i.e., serum sickness, systemic lupus erythematosus, vasculitis, Behcet's disease, sarcoidosis, iatrogenic, etc. The pathogenesis of the meningitis is better understood now due to increasing research activities: host factors, characteristics & virulence of the infective microorganism, level of innoculum, etc. Irrespective of the type of etiological factor involved, the clinical features of meningism are more or less same: headaches, neck stiffness, vomiting and fever. However depending on the nature of the etiological factor, there may be prodromal symptoms, systemic symptoms, as well as the features of neurological involvement. Ideally, brain imaging (CT head) is carried out prior to the lumbar puncture to exclude the cerebral mass lesion and raised ICP. The diagnosis mainly depends upon the detailed analysis of the cerebrospinal fluid (CSF). CSF, blood, urine, stool and throat swabs may be sent, where indicated, for culture and antimicrobial sensitivity. This may be supported by hematological, biochemical and microbiological studies, neuro-imaging, radiological studies of the other organ systems, etc. CSF, blood, urine, stool and throat swabs may be sent for culture, serological testing and antimicrobial sensitivity. Recently developed molecular technologies help in precise diagnosis. The management is mainly focused on the treatment of the causative factors for meningitis along with the symptomatic supportive care. It is also pertinent to exclude more serious causes with certainty at that time. Inpatient care with anti-microbial drugs, bed rest, analgesics, anti-emetics, anti-cancer therapy, steroids and supportive measures are important steps in the overall management. Efficacy of the treatment must be reviewed as per the practices of the evidence based medicine. Though, in great majority of cases, the diagnosis is reached quickly and appropriate treatment started in time with a good outcome as compared to before. But, in some cases, this may not be possible. Occasionally, the differentiation of infective from non-infective etiologies may be perplexing and rarely there may be more than one causative factor for meningitis. Meningitis, in general, carries higher risks of morbidities and mortality and therefore needs precise diagnosis and appropriate management strategies in time to optimize the outcome. Unfortunately, despite much scientific advancement in diagnostics and therapeutics, there is still considerable morbidity and mortality. In future, we need to focus on the preventive measures (public educational activities, immuno-prophylaxis and chemo-prophylaxis), modern diagnostics and appropriate treatment strategies to achieve optimum results.