Meningitis and Encephalitis

Question 1

• 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.

Answer 1

Meningitis

Question 2

Inflammation of the brain itself

Answer 2

Encephalitis

Question 3

• 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).

Answer 3

Meningitis

Question 4

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

Answer 4

Meningitis

Question 5

Meningitis typically occurs through two routes of inoculation:

Answer 5

• 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).

Question 6

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.

Answer 6

Meningitis

Question 7

Classic Meningeal Tetrad

Answer 7

• 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.

Question 8

Labs for Meningitis

Answer 8

lumbar puncture with CSF analysis is always recommended

Question 9

Imaging for meningitis

Answer 9

• CT is the preferred imaging modality.
• Ideally CT should be done prior to
  lumbar puncture and CSF collection.

Question 10

Treatment of Meningitis

Answer 10

Antibiotic Treatment:
- Ceftriaxone 2g IV q12h x 7 days
- Pen-G 4 million units IV q4h x 7 days
Steroids
- dexamethasone 4mg IV

Question 11

What should be done for meningitis with Signs of ICP (altered mental status, neurologic deficits, non-reactive pupils, bradycardia)

Answer 11

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)

Question 12

Chemoprophylaxis for meningitis

Answer 12

• Ceftriaxone 250mg IM one time
• Ciprofloxacin 500mg PO one time

Question 13

Who is chemoprophylaxis indicated for with meningitis

Answer 13

• 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).

Question 14

Disposition for meningitis

Answer 14

Medical Evacuation is indicated for any patient with suspected meningitis, regardless of etiology or status.