encephalitis
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Introduction
Also see
Etiology
- infection
- viral encephalitis (48%)
- Herpes simplex virus (19%)
- reactivation of latent infection
- Varicella zoster virus (11%)
- acute infection or reactivation of latent infection
- increased risk with HIV1 infection
- enterovirus
- encephalitis viruses
- West Nile virus (9%)
- Epstein-Barr virus (3%)
- HIV1 infection* (2%)
- rabies virus
- Herpes simplex virus (19%)
- bacterial infection
- protozoan infection
- viral encephalitis (48%)
- autoimmune disease (22%)
- malignancy
- idiopathic (30%)[4]
* acute encephalitis associated with regional lymphadenopathy
Epidemiology
- enterovirus: late summer or fall
- West Nile virus: mosquito-borne infection, summer or fall (June-October)
- rabies: bite from infected mammal, generally bat
Pathology
- inflammation of the brain parenchyma
Clinical manifestations
- HSV1: fever, altered mental status, temporal lobe epilepsy
- Herpes zoster: dermatomal cutaneous lesions variably present
- enterovirus: fever, altered mental status, variable rash, oral lesions
- West Nile virus: fever, altered mental status, muscle weakness variable (asymmetric flaccid paralysis possible), parkinsonism, rarely seizures
- Rabies virus: paresthesias at site of innoculation, hydrophobia, progressive obtundation[6]
Laboratory
- CSF analysis
- CSF cell count:
- lymphocyte predominance
- CSF herpes simplex virus DNA (all cases of encephalitis)[6]
- CSF varicella-zoster virus DNA
- CSF enterovirus RNA
- West Nile virus IgM in CSF
- CSF Rabies virus RNA
- CSF cell count:
- NMDA receptor IgG in CSF
- nape of neck biopsy (nuchal skin biopsy) for immunohisochemstry (rabies)
- also see paraneoplastic limbic encephalitis
- see ARUP consult[1]
Diagnostic procedures
Radiology
- MRI
- bilateral temporal lobe involvement with HSV1
Complications
- mortality 9% during hospitalization & 17% at 1 year
- factors associated with poor outcome[4]
- age >= 65 years
- immunocompromise
- coma
- acute thrombocytopenia
- need for mechanical ventilation
Differential diagnosis
- autoimmune encephalitis
- insidious onset, positive nonspecific serum antibodies suggest other diagnosis[9]
Management
- acyclovir for HSV1 & Herpes zoster
- supportive care for enterovirus, West Nile virus & rabies
- see specific etiology
- prognosis
- minimal or no disability at hospital discharge in 49% of patients & 60% of patients at 1 year
- prophylaxis for close contacts of patient with rabies[6]
More general terms
More specific terms
- Bickerstaff brainstem encephalitis
- encephalitis lethargica; sleeping sickness; von Economo's disease
- encephalomyelitis
- GABA-A receptor antibody encephalitis
- limbic encephalitis
- meningoencephalitis
- paraneoplastic brainstem encephalitis; paraneoplastic rhombencephalitis
- Rasmussen's encephalitis
- Rassmusen's encephalitis
- viral encephalitis
References
- ↑ 1.0 1.1 ARUP Consult: Encephalitis, Infectious The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/encephalitis-infectious
- ↑ Glaser CA, Honarmand S, Anderson LJ et al Beyond viruses: clinical profiles and etiologies associated with encephalitis. Clin Infect Dis. 2006 Dec 15;43(12):1565-77 PMID: https://www.ncbi.nlm.nih.gov/pubmed/17109290
- ↑ Tunkel AR, Glaser CA, Bloch KC et al The management of encephalitis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2008 Aug 1;47(3):303-27 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18582201 (corresponding National Guideline Clearinghouse entry withdrawn Dec 2013)
- ↑ 4.0 4.1 4.2 Singh TD et al. The spectrum of acute encephalitis: Causes, management, and predictors of outcome. Neurology 2015 Jan 27; 84:1 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/25540320 <Internet> http://www.neurology.org/content/early/2014/12/24/WNL.0000000000001190
- ↑ Wyllie E, Rincon SP, Pierce VM Case 16-2015 - A 9-Year-Old Girl with Loss of Consciousness and Seizures. N Engl J Med 2015; 372:2050-2058. May 21, 2015 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/25992750 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMcpc1501149
- ↑ 6.0 6.1 6.2 6.3 6.4 Medical Knowledge Self Assessment Program (MKSAP) 17, 19 American College of Physicians, Philadelphia 2015, 2021
Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022 - ↑ Venkatesan A, Geocadin RG. Diagnosis and management of acute encephalitis: A practical approach. Neurol Clin Pract. 2014 Jun;4(3):206-215. PMID: https://www.ncbi.nlm.nih.gov/pubmed/25110619 Free PMC Article
- ↑ Venkatesan A, Tunkel AR, Bloch KC et al Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the international encephalitis consortium. Clin Infect Dis. 2013 Oct;57(8):1114-28. PMID: https://www.ncbi.nlm.nih.gov/pubmed/23861361 Free PMC Article
- ↑ 9.0 9.1 Flanagan EP et al. Autoimmune encephalitis misdiagnosis in adults. JAMA Neurol 2022 Nov 28; [e-pub]. PMID: https://www.ncbi.nlm.nih.gov/pubmed/36441519 PMCID: PMC9706400 Free PMC article https://jamanetwork.com/journals/jamaneurology/fullarticle/2799083
- ↑ NINDS Encephalitis and Meningitis Information Page https://www.ninds.nih.gov/Disorders/All-Disorders/Meningitis-and-Encephalitis-Information-Page
Meningitis and Encephalitis Fact Sheet https://www.ninds.nih.gov/disorders/patient-caregiver-education/fact-sheets/meningitis-and-encephalitis-fact-sheet