Meningitis

It is the inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges

Layers of meninges

• pia matter (inner layer)
• arachnoid (middle layer)
• subarachnoid space (outer layer)

Bacterial meningitis is rare, but is usually serious and can be life-threatening if not treated right away. Viral meningitis (also called aseptic meningitis) is relatively common and far less serious. It often remains undiagnosed because its symptoms can be similar to those of the common flu.



Etiology:

• meningococcus - most dangerous
• pneumococcus
• streptococcus - causes adult meningitis
• hemophilus influenzae - causes pediatric meningitis

Mode of transmission:

• airborne transmission (droplet nuclei)

Signs and Symptoms:

• headache 
• photophobia
• projectile vomiting
• fever
• chills
• anorexia
• general body malaise
• weight loss
• increase in ICP
• seizure activity
• abnormal posturing (decorticate and decerebrate)
• signs of meningeal irritation (Nuchal rigidity or stiff neck, Opisthotonus (arching of back), (+) kernigs sign (leg pain), (+) brudzinski sign (neck pain) )

Diagnostic procedure:

• Lumbar puncture (also called a spinal tap) is a common medical test that involves taking a small sample of cerebrospinal fluid (CSF) for examination. In a lumbar puncture, a needle is carefully inserted into the lower spine to collect the CSF sample.

Treatment:

• bacterial meningitis (emperic antibiotics and steroids)
• viral meningitis (antiviral ( aciclovir))
• fungal meningitis (antifungals (amphotericin B and flucytosine) )

Prevention:
Routine immunization vaccines against Hib, measles, mumps, polio, meningococcus, and pneumococcus can protect against meningitis caused by these microorganisms.