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Meningitis

Bacterial

Strep Pneumo
Meningococcal
- G- diplococci
- Clinical: sore throat, HA, drowsiness, fever, neck stiffness, photophobia , hemorrhagic skin rash with septicemia
H. influenza (infants, young children)
Listeria monocytogenes
E. coli, Group B strep
TB
- Clinical: always focus of infx outside CNS, but 25% without signs/symptoms. Usually gradual onset, though occasionally rapid and presents like SAH

Treatment of Bacterial Meningitis

Community Acquired
- Vanco (for resistant pneumococcus), plus
- Ceftriaxone 2g or cefotaxime, or
- Ampicillin (age > 50) +/- gentamicin for synergy (certainly add if bacteremia / sepsis) & monitor drug levels (peak and trough) & monitor for toxicity (ototoxicity, nephrotoxicity)
- Dexamethasone 10mg IVq6h x4d
- Rifampin prophy for close contacts of pt with meningococcal meningitis; cipro prophy for adult contacts?
Immunocompromised
- Ceftriaxone 2g IV q12h or cefotaxime or cefepime (if pseudomonas risk); plus
- Vanco; plus
- Ampicillin 2.0g IV q4h
- Steroids clearly indicated for Strep pneumo; some would give for all bacterial meningitis
Pen Allergy
- Chloramphenicol (covers meningococcus, H. influenza, S. pneumo, E. coli
Duration of Treatment
Practice Guidelines for Bacterial Meningitis • CID 2004:39 (1 November) • 1281

Microorganism : Duration of therapy, days

Viral Meningitis

Overview: The most common meningitis
Viruses
- HSV, mumps, lyphocytic choriomeningitis, polio, coxsackie, echo, japanese encephalitis, eatern and western equine, louping ill, HIV
- Dx: PCR
- Generally speaking, benign course with complete recovery

Fungal Meningitis

Protozoal Meningitis

Naegleria
- stagnant fresh water, inhaled --> meninges
- healthy, non-immunosuppressed patient
Acanthamoeba spp.
- cause chronic granulomatous amebic encephalitis

Encephalitis

Overview: Usually viral, though infectious agent often not identified. Brain parenchyma inflammed in encephalitis, as oppossed to the lining of the brain in meningitis.
Clinical: AMS, szr, depressed consciousness, nausea, vomiting, fever
Most common cause: HSV
Causative agents
- Viruses
- - HSV
  - VZV
  - CMV
  - HIV
  - West Nile
  - Mumps
  - Rabies
  - Louping ill
  - Polio, other enteroviruses
  - Eastern and western equine encephalitis
  - St. Louis encephalitis
  - Japanese encephalitis
  - Californian encephalitis
  - Rubella
  - Measles
  - JC virus
- Prion
- - CJD
- Protozoa and fungi
- - toxo
  - crypto
  - plasmodium falciparum
  - Trypanosoma spp.
- Bacteria
- - Treponema pallidium
  - Mycoplasma pneumoniae
  - Borrelia burgdorferi
Treatment
- HSV
- - Acyclovir IV x21d
- Rabies
- - Following a bite wound:
  - - clean the wound, debride
    - Confirm if animal had rabies
    - Give human rabies immunoglobulin
    - - give half IM and half directly into the wound
    - Active immunization with killed virus
- Other
- - supportive
West Nile Virus
- Clinical: encephalitis
- Dx: viral RNA or IgM in serum or CSF
- Tx: supportive

Brain Abscess

Overview: look for predisposing factor (surgery, trauma, chronic osteomyelitis of adjacent bone, septic empbolism, chronic cerebral anoxia). Acute abscesses generally mixed oropharyngeal flora; chronic more typically TB or C. neoformans. If immunosuppressed, consider fungi, protozoa
Causes
- Bacterial: TB, syphilis, Brucellosis, Lyme, Nocardia, Actinomycosis
- Fungal: Crypto, Coccidio, Histo, Candida, Blasto
- Parasitis: Toxo, cysticercosis
Dx:
- CT or MRI
- Gold standard = surgical drainage with gram stain & culture
- Note: LP is contraindicated!
Tx: surgical drainage if abscess well encapsulated. ABx 1-2 months IV ABx; give longer course especially if not surgically drained.
- Treat at minimum until there is documented radiologic improvement
- Consider treatment until complete radiologic resolution
- Mean time to radiologic resolution is 4 months, but may take up to one year for MRI enhancement to resolve
Recurrence rate: ~ 8 %

CNS Disease Caused by Parasites

Tetanus and Botulism

Overview: Bacteria that release toxins which act on the CNS
Tetanus
- toxin carried by peripheral nerves to the CNS, bines neurons, blocks release of inhibitory molecules in the synapse --> unopposed muscle activation
- Clinical: hyperreflexia, muscle rigidity, uncontrolled muscle spasms, lockjaw (contraction of jaw muscle), dysphagia, neck stiffness, eventual respiratory failure
- Dx: clinical
- Tx: human antitetanus immunoglobulin
- - wound care, debridement, penicillin
Botulism
- Cl botulinum toxin blocks acetylcholine release from peripheral nerves --> paralysis
- Clinical: weakness and paralysis, which is descending. Dysphagia, diplopia, vomiting, vertigo, respiratory failure.
- Dx: clinical
- Tx: trivalent antitoxin

Myelopathy / Myelitis

:: inflammation of the spinal cord itself
Clinical: motor weakness, sensory loss
Anterior horn cells may be infected by polio, coxsackie, enterovirus 71, West Nile Virus
Herpes family viruses can cause acute myelitis

Acute Hemorrhagic Leukoencephalopathy

Infection triggers an autoimmune response which results in perivascular demyelination and hemorrhage in the brain parenchyma
- hyperacute form of acute disseminated encephalomyelitis (ADEM), characterized by vascular necrosis and demyelination
Clinical: fever, headache, rapid progression to coma; death typically within one week
May follow viral infection, drug exposure, or vaccination
- Influenza A
- Varicella
- Measles