ID
Viral Encephalitis
search
Viral Encephalitis
, Encephalitis
See Also
Meningitis
HSV Encephalitis
Progressive Multifocal Leukoencephalopathy
West Nile Virus Encephalitis
NMDA Encephalitis
Causes
Viral (most cases)
Causative organism identified in only half of cases
Common
Enterovirus Meningitis
(50.9% of all
Meningitis
cases in adults)
Herpes Simplex Encephalitis
(8.3% of all
Meningitis
cases in adults, Very poor prognosis)
Adults:
Herpes Simplex Virus
I
Neonates:
Herpes Simplex Virus
II
Varicella Zoster Virus
(15% of cases)
Mumps
(
Gene
rally benign)
Arbovirus
(1.1% of all
Meningitis
causes in adults)
Eastern equine Encephalitis (70-90% poor prognosis)
Western equine Encephalitis (2-20% poor prognosis)
St. Louis Encephalitis (2-20% poor prognosis)
Powassan Encephalitis
(
Tick Borne Illness
, 50% with
Cognitive Impairment
, 10-15% mortality)
California Encephalitis (generally benign)
Venezuelan equine Encephalitis (generally benign)
West Nile Virus Encephalitis
(severe in elderly)
Japanese Encephalitis
(severe disease is uncommon, but 30% mortality when it occurs)
Limited to travelers to rural and periurban Southeast Asia, Western Pacific
Uncommon
Parvovirus B19
Epstein-Barr Virus
Influenza
Rabies
(rare in U.S.)
Immunocompromised
Cytomegalovirus
(
AIDS
)
Causes
Other non-viral (uncommon)
Bacteria
l causes
Tuberculosis
(15% of cases)
Listeria (10% of cases)
Borrelia Burgdorferi
(
Lyme Disease
)
Bartonella Henselae
(
Cat Scratch Disease
)
Rickettsia rickettsii
(
Rocky Mountain Spotted Fever
)
Mycoplasma pneumoniae
Treponema pallidum
(
Syphilis
)
Anaplasmosis
Ehrlichiosis
Fungal causes
Cryptococcus
Coccidioides
Histoplasma
Parasitic causes
Taenia solium
(
Cysticercosis
)
Plasmodium Falciparum
(
Malaria
)
Toxoplasma gondii
(
Toxoplasmosis
)
Trypanosoma cruzi
(
Chagas Disease
)
Miscellaneous causes
NMDA Encephalitis
(very common in age <30 years old)
Symptoms
Sudden high fever
Severe
Headache
Meningismus (e.g. Stiff neck)
Altered Level of Consciousness
Lethargy
Mental confusion
Coma
Behavior change
Seizure
Dysarthria
Dysphasia
Nausea
and
Vomiting
Photophobia
Hemiparesis
Cranial Nerve
deficits
Visual Field
loss
Signs
Variable signs depending on involvement and organism
See
HSV Encephalitis
See
West Nile Virus Encephalitis
(C0043124)
Tremor
Tongue
Lips
Hands
Other neurologic changes
Ataxia
Spastic paralysis
Deep Tendon Reflex
es exaggerated
Signs of
Increased Intracranial Pressure
Differential Diagnosis
See
Altered Level of Consciousness Causes
See
Drug Induced Altered Level of Consciousness Causes
Labs
See
Altered Level of Consciousness
for general labs
Complete Blood Count
(CBC)
Mild
Leukocytosis
Mild
Lymphocytosis
Serum
Electrolyte
s and
Glucose
Specific testing
Strep Throat
swab
Influenza
nasal swab
St Loius Encephalitis serum IgM
West Nile Virus
serum IgM
Western Equine Encephalitis serum IgM
Mycoplasma pneumoniae
IgM
Lyme Disease
Screening
Serum RPR for
Syphilis
CMV culture from urine or
Saliva
(
Test Sensitivity
approaches 100%)
Varicella culture from vessicles
Herpes culture from
Vesicle
s, mucous membranes and urine
Cerebrospinal Fluid (CSF)
Initial tests
CSF Gram Stain
CSF Culture
CSF Protein
CSF Glucose
CSF Cell Count
with differential
Typical non-specific findings
Increased Intracranial Pressure
Increased
Protein
Lymph
ocytic
Pleocytosis
CSF Antigens
(indicated if CSF findings not consistent with
Bacterial Meningitis
)
CSF
HSV PCR
(Send in all cases of suspected Encephalitis)
CSF enterovirus PCR
Imaging
CT Head
Indicated prior to
Lumbar Puncture
if focal neurologic findings or signs of
Increased Intracranial Pressure
MRI Brain
See
HSV Encephalitis
for HSV specific findings
CMV Encephalitis
Periventricular intracranial calcifications
Cerebral dysgenesis
Congenital Toxoplasmosis
Multiple ring-enhancing lesions
Cysticercosis
Cyst
ic lesions with variable calcifications
Ring enhancement suggests cyst degeneration
Management
Empiric HSV management
Start
Acyclovir
empirically for all Encephalitis cases
Acyclovir
10 mg/kg IV over 1 hour every 8 hours
Continue until diagnosis is excluded by HSV
CSF PCR
Cerebral
Edema
Mannitol
Corticosteroid
s
Only for specific indications
Avoid in
Herpes Simplex Virus
Seizure
control
Specific empiric Management if cause suspected (Keep high level of suspicion for treatable etiologies)
HSV Encephalitis
Acyclovir
IV (see dosing above)
CMV Encephalitis (
AIDS
)
Ganciclovir
or
Foscarnet
Rocky Mountain Spotted Fever
Doxycycline
for any age where this is strongly suspected (causes tooth staining in under age 8 years)
Cat-Scratch Disease
Encephalitis
Azithromycin
or
Doxycycline
Mycoplasma pneumoniae
Encephalitis
Azithromycin
or
Doxycycline
Lyme Encephalitis
Ceftriaxone
75-100 mg/kg up to 2 grams IV q24 hours
Influenza Encephalitis
Oseltamivir
(
Tamiflu
)
Course
Symptomatic: weeks to months
Prognosis
Mortality during acute illness: 10%
High rate of
Disability
following infection
Variable depending on specific etiology
References
(2016) Sanford Guide, accessed 4/11/2016
Fuchs and Yamamoto (2012) APLS, Jones and Bartlett, Burlington, p. 180-3
Mailles (2009) Clin Infect Dis 49(12):1838-47 +PMID:19929384 [PubMed]
Singh (2015) Neurology 84(4):359-66 +PMID:25540320 [PubMed]
Type your search phrase here