Aseptic/Viral Meningo-encephalitis

 

Aseptic Meningitis—"pts who have clinical and lab evidence for meningeal inflammation with neg. routine bacterial Cx"

Viral Meningitis—acute viral infection…a cause of aseptic meningitis

Encephalitis—"infection involving brain parenchyma characterized by cognitive deficits"

Meningoencephalitis—term that articulates the overlap between the 2 entities

Postinfectious encephalomyelitis—likely immune mediated inflammation/demyelination in the absence of identifiable virus

Myelitis—inflammation of the spinal cord

 

Lymphocytic Predominance, Normal Glucose CSF profile

 

Infectious Causes

Non Infectious Causes

Common

Viral Meningitis or Encephalitis
Post Infectious Encephalmyeltis

  

Uncommon

Partially treated bacterial meningitis
Parameningeal infection (epidural abscess, brain abscess)
Early fungal/TB meningitis
Parasitic Dz (trich, toxo, cysticerosis)
Whipple’s Disease

Neoplastic Meningitis
Uveoencephalitides
Disseminated lupus
Primary cerebral granulomatous arteritis

From: Dr. Peacock’s Acute CNS Infection Handout

Aseptic Meningitis/Encephalitis

Viruses:   

HSV, HIV, Enteroviruses (>50% of cases) LCM (lymphocytic choriomeningitis virus (10-15% of cases), EEE, WEE, LaCrosse, VZV, Mumps, rabies, West Nile

See table on back for other, nonviral etiologies

Tips from Hx & Exam

  1. Take a travel & exposure history including exposure to rodents (LCM), ticks, TB, sexual activity (HSVm HIV, syphilis), contact with others (enteroviruses)
  2. Carefully consider nonviral etiology especially drug associated
  3. Clues from exam: Rashà enterovirus, HSV…Parotitis/Orchitisà LCM or mumps

CSF

  1. Increased WBC—usually <250 with lymphocyte predominance
  2. Elevated protein –usually <150
  3. Normal glucose—usually , but can be slightly low
  4. RBC’s absent—usually

**Considerable overlap can occur with bacterial meningitis. Nomograms can be helpful (using nomogram with this pt. yields .01 probability of bacterial vs viral)

Other diagnostics to consider:

Viral cultures
PCR (for HSV & enterovirus)
Acute & convalescent sera (LCM, EBV,mumps
HIV Ab, consider HIV RNA or p24 Ag

MS-

WBC—NL in 67% (rarely exceeds 50)
Protein/Albumin—usually NL
Inc CSF immunoglobulins
Oligoclonal bands in 85-90% (can occur in non MS pts)

Transverse Myelitis
Devic’s Dz- bilateral optic neuropathy and cervical myelopathy ("an MS variant")—can be ADEM or other autoimmune disease

Others in the Differential (see table)
    1. Assoc with: EBV, MMR, VZV, HSV, Coxsackie, Lyme, rabies, drugs (Sulfa)
    2. Hallmark: focal or multifocal neurological disorder following exposure to virus or vaccine. Sometimes a prodrome of fever, malaise, myalgia
    3. Characteristic: bilateral optic neuritis, meningismus, loss of DTR’s , LOC, fever, (MS has unilat optic neuritis, diplopia, hyperreflexia, preserved LOC)
    4. MRI—multifocal lesions
    5. CSF—WBC <100, modest protein increase, no OCB’s

 

 

AEbright 2000