Meningitis

• Inflammation of leptomeninges (arachnoid and pia mater) including subarachnoid space and CSF

• C/S are F, H/A, stiff neck, and behavior changes

• CSF changes in meningitis

  • Bacterial

    • Neutrophilic pleocytosis (pleocytosis = increase in cells)

    • Elevated protein

    • Reduced sugar

  • Viral

    • Lymphocytic pleocytosis (may have PMN pleocytosis early on)

    • Protein less elevated than bacterial, sugar normal

• Bacterial

  • Also called acute meningitis or purulent meningitis

  • Caused by

    • Neonates: E. coli, Streptococcus agalactaciae (Group B strep), and Listeria

    • Kids: H. influenzae (incidence decreased due to vaccine)

    • Young adults: N. meningitidis

    • Older adults: S. pneumoniae, Listeria

    • Open head trauma: staph, strep, other flora

  • Subdural empyema

    • Spread of infection from skull or sinus to subdural space

    • May be bacterial (often fungal)

    • Can produce mass effect

    • Thrombophlebitis of bridging veins may result in brain infarction

    • Resolution from dural side

• Viral

  • Also called lymphocytic or aseptic meningitis

  • Can be caused by numerous viruses, but enteroviruses are very common causes in summertime (1/3 of cases have unknown cause)

  • Has to be treated symptomatically, since a/b don’t work

• Chronic

  • Usually fungal or TB

  • Cryptococcus meningitis – form of fungal meningitis in AIDS and other immunocompromised patients

• TB meningitis

  • Chronic meningitis usually localized to the base of the brain

  • If gets into brain (encephalitis) will form discrete tuberculomas in the brain matter

    • 25% of intracranial masses in South America and India

    • Adult lesions are supratentorial, kids’ lesions are infratentorial

Category: Pathology Notes