Meningitis and Encephalitis Flashcards
- Defined as inflammation of the meninges (dura mater, arachnoid mater, and pia mater) that line the vertebral canal/skullenclosing spinal cord/brain.
- Serious disorder caused both infectious & non-infectious etiologies.
- Prior to the antibiotic era, was universally fatal.
- Even with ABX therapy & imaging, condition still carries a ~ 14% mortality rate.
Meningitis
Inflammation of the brain itself
Encephalitis
- Bacterial etiologies:
Streptococcus Pneumonia, Group B Streptococcus, N. Meningitidis, H. influenza, E. Coli, Listeria monocytogenes - Viral etiologies:
Enteroviruses (most common), coxsackieviruses, echoviruses, WNV, Influenza, HSV, VZV, EBV, arboviruses - Other etiologies: Fungal, Parasitic, Amebic, Non-infectious (cancers, lupus, certain meds, head injury, brain surgery).
Meningitis
Risk factors that should increase clinical suspicion:
- Close contact exposures (military barracks, college dorms)
- Incomplete vaccinations
- Immunosuppression
- > 65 y/o & < 5 y/o
- Alcohol use disorder
Meningitis
Meningitis typically occurs through two routes of inoculation:
- Hematogenous seeding
Bacteria colonize in nasopharynx & enter bloodstream. Upon making their way to the subarachnoid space, the bacteria cross the blood-brain barrier, causing a direct inflammatory and immune-mediated reaction. - Direct contiguous spread
Organisms enter CSF via neighboring anatomic structures (otitis media, sinusitis) or foreign objects (medical devices, penetrating trauma).
In adults, evaluation is centered on:
- Identifying focal neurologic deficits
- (Brudzinski & Kernig signs)
- may have characteristic petechiae & purpura
- Cranial nerve abnormalities are seen in 10%-20% of patients.
Meningitis
Classic Meningeal Tetrad
- Fever, nuchal rigidity, altered mental status, & severe headache
- However, the presence of all four signs is not necessary for clinical diagnosis; many patients may only have 2-3 out of the 4 signs.
Labs for Meningitis
lumbar puncture with CSF analysis is always recommended
Imaging for meningitis
- CT is the preferred imaging modality.
- Ideally CT should be done prior to
lumbar puncture and CSF collection.
Treatment of Meningitis
Antibiotic Treatment:
- Ceftriaxone 2g IV q12h x 7 days
- Pen-G 4 million units IV q4h x 7 days
Steroids
- dexamethasone 4mg IV
What should be done for meningitis with Signs of ICP (altered mental status, neurologic deficits, non-reactive pupils, bradycardia)
Elevating the head of the bed to 30 degrees, inducing mild hyperventilation in the intubated patient, osmotic diuretics such as 25% mannitol or 3% saline (CALL MO)
Chemoprophylaxis for meningitis
- Ceftriaxone 250mg IM one time
- Ciprofloxacin 500mg PO one time
Who is chemoprophylaxis indicated for with meningitis
- Chemoprophylaxis is indicated for close contacts
- Close contacts include:
-housemates, significant others, those who have shared utensils, and health care providers in proximity to secretions (providing mouth-to-mouth resuscitation, intubating without a facemask).
Disposition for meningitis
Medical Evacuation is indicated for any patient with suspected meningitis, regardless of etiology or status.