Guideline sources The following summarized guidelines for the evaluation and management of encephalitis are prepared by our editorial team based on guidelines from the Association of British Neurologists (ABN/BIANG 2012), the Association of British Neurologists (ABN/BPAIIG 2012), and the Infectious Diseases Society of America (IDSA 2008). 1 2 3 Guidelines 1. Screening and diagnosis Clinical presentation: suspect encephalitis or another CNS infection in patients with current or recent febrile illness with altered behavior, cognition, personality or consciousness, or new seizures or focal neurological signs. B Show 4 more 2. Diagnostic investigations Clinical assessment: assess for epidemiologic clues and risk factors to identify potential etiologic agents in patients with encephalitis. B Show 2 more Evaluation for infectious etiology: https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 1/6 6/29/23, 4:15 AM Encephalitis Pathway Evaluation for infectious etiology: As per ABN 2012 guidelines, determine investigation priority based on the patient's clinical presentation. B Show 15 more As per IDSA 2008 guidelines, obtain specific diagnostic studies in most patients with encephalitis: Situation Guidance Culture of respiratory secretions and nasopharynx, throat, and stool specimens Viruses DFA of sputum for respiratory viruses Blood cultures Bacteria CSF cultures Serologic testing (acute and convalescent phase) for Mycoplasma pneumoniae PCR of respiratory secretions for Mycoplasma pneumoniae Serologic testing (acute and convalescent phase) for Rickettsia rickettsi, Ehrlichia chaffeensis, and Anaplasma phagocytophilum Rickettsiae and ehrlichiae DFA and PCR of skin biopsy specimen (if rash present) for Rickettsia rickettsiae Blood smears for morulae PCR of whole blood and CSF specimens for Ehrlichia and Anaplasma species Serum RPR and FTA-ABS Spirochetes Serologic testing for Borrelia burgdorferi (ELISA and Western blot) CSF Venereal Disease Research Laboratory CSF Borrelia burgdorferi serologic testing (ELISA and Western blot) Calculate IgG antibody index CSF FTA- ABS CXR Mycobacteria PCR and culture of respiratory secretions CSF AFB smear and culture CSF PCR (Gen-Probe amplified Mycobacterium tuberculosis direct test) Blood cultures Fungi CSF cultures https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 2/6 6/29/23, 4:15 AM Encephalitis Pathway Serum and CSF cryptococcal antigen Urine and CSF Histoplama antigen Serum IgG for Toxoplasma gondii in immunocompromised patients. B Protozoa Show 10 more Neuroimaging: As per ABN 2012 guidelines, obtain MRI (including DWI) as the preferred imaging modality as soon as possible (ideally 24 hours of hospital admission, but certainly within 48 hours) in all patients with suspected encephalitis, if the diagnosis is uncertain. B Show 3 more As per IDSA 2008 guidelines, obtain MRI for the evaluation of patients with encephalitis. A Obtain CT, with and without contrast enhancement, if MRI is unavailable, impractical, or cannot be obtained. B Electroencephalography: As per ABN 2012 guidelines, do not obtain EEG routinely in all patients with suspected encephalitis. D Show 2 more As per ABN 2012 guidelines, obtain an EEG in pediatric patients with suspected chronic viral encephalitis, such as subacute sclerosing panencephalitis. B As per IDSA 2008 guidelines, obtain an EEG in patients with encephalitis to identify nonconvulsive seizure activity in confused, obtunded, or comatose patients. B 3. Diagnostic procedures Lumbar puncture: perform lumbar puncture as soon as possible after hospital admission in all patients with suspected encephalitis, unless there is a clinical contraindication. B Consider performing an immediate lumbar puncture after CT on a case-by-case basis, unless the imaging reveals significant brain shift or tight basal cisterns due to or causing raised ICP or an alternative diagnosis or the patient's clinical condition changes. B Show 7 more Brain biopsy: As per ABN 2012 guidelines, do not perform a brain biopsy in the initial assessment of suspected acute viral encephalitis. Consider performing a stereotactic biopsy in patients with suspected encephalitis if no diagnosis has been made after the first week, especially if there are focal abnormalities on imaging. D Show 2 more As per IDSA 2008 guidelines: Do not perform brain biopsy routinely in patients with encephalitis. D Consider performing brain biopsy in patients with encephalitis of unknown etiology with deteriorating condition despite treatment with acyclovir. C https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 3/6 6/29/23, 4:15 AM Encephalitis Pathway 4. Medical management Setting of care: obtain immediate neurological specialist consultation in patients with suspected acute encephalitis and manage them in a setting where a clinical neurological review can be obtained as soon as possible and definitely within 24 hours of referral. B Show 4 more Empirical therapy: As per ABN 2012 guidelines, initiate IV aciclovir (10 mg/kg TID) if the initial CSF and/or imaging findings suggest viral encephalitis, or within 6 hours of admission if these results will not be available, or if the patient is very unwell or deteriorating. B Show 3 more As per IDSA 2008 guidelines, initiate acyclovir in all patients with suspected encephalitis, pending results of diagnostic studies. B Show 2 more Specific therapy, viruses: As per BIANG/ABN 2012 guidelines, continue IV acyclovir treatment for 14-21 days in patients with proven HSV encephalitis, B and perform a repeat lumbar puncture at this time to confirm the CSF is negative for HSV by PCR. Continue IV acyclovir if the CSF is still positive with weekly PCR until it is negative. B Show 8 more As per IDSA 2008 guidelines, administer acyclovir in patients with HSV infection. A Show 12 more Specific therapy (bacteria): administer chloramphenicol, ciprofloxacin, doxycycline, ampicillin, or TMP-SMX in patients with encephalitis caused by Bartonella bacilliformis. B Show 4 more Specific therapy (mycobacteria): complete a 4-drug antituberculous therapy in patients with encephalitis caused by Mycobacterium tuberculosis. B Add adjunctive dexamethasone in patients with meningitis. B Specific therapy (rickettsiae and ehrlichiae): administer doxycycline in patients with encephalitis caused by Anaplasma phagocytophilum. B Show 3 more Specific therapy (spirochetes): Administer ceftriaxone, cefotaxime, or penicillin G in patients with Borrelia burgdorferi encephalitis. B Administer penicillin G, B or ceftriaxone as an alternative, B in patients with Treponema pallidum encephalitis. B Specific therapy (fungi): administer fluconazole as the first-line therapy in patients with encephalitis caused by Coccidoides species. B Consider administering itraconazole B , voriconazole B , or IV or intrathecal amphotericin B B as second-line choices. B Show 2 more Specific therapy (protozoa): consider administering TMP-SMX plus rifampin plus ketoconazole or fluconazole plus sulfadiazine plus pyrimethamine in patients with Acanthamoeba encephalitis. C https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 4/6 6/29/23, 4:15 AM Encephalitis Pathway Show 6 more Specific therapy (helminths): consider administering albendazole plus diethylcarbamazine in patients with encephalitis caused by Baylisascaris procyonis. C Consider administering adjunctive corticosteroids. C Show 2 more Specific therapy (acute disseminated encephalomyelitis): administer high-dose corticosteroids in patients with acute disseminated encephalomyelitis. B Perform plasma exchange B and administer IVIG as an alternative option. B 5. Specific circumstances Patients with autoimmune encephalitis: include antibody-mediated encephalitis in the differential diagnosis of all patients with suspected encephalitis because of the poor outcomes if left untreated. B Show 3 more 6. Follow-up and surveillance Follow-up: Do not discharge patients from the hospital without either a definite or suspected diagnosis. Formulate an arrangement for the outpatient follow-up (to include at least one follow-up appointment) and plans for ongoing therapy and rehabilitation at a discharge meeting. D Ensure that all patients have access to assessment for rehabilitation, irrespective of age. B Clinical findings Symptoms Past medical history Chills Immunocompromising condition Confusion Radiation therapy to the head area Emotional lability Fatigue Lab findings Fever Headache CSF RBCs Myalgia CSF protein Nausea Imaging findings Personality or behavioral changes Cerebral edema Seizure Sleepiness Cytological findings Vomiting CSF WBC count Neurological exam Altered mental status https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 5/6 6/29/23, 4:15 AM Encephalitis Pathway Aphasia Ataxia Coma Cranial nerve palsy Focal neurologic deficits Hemiparesis Meningismus Speech disturbance Hematological findings WBC count blood leukocyte count blood platelet count EEG findings Nonconvulsive status epilepticus Periodic lateralizing epileptiform discharges References 1. T Solomon, B D Michael, P E Smith et al. Management of suspected viral encephalitis in adults Association of British Neurologists and British Infection Association National Guidelines. J Infect. 2012 Apr;64 4 347 73. Open 2. 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. Open 3. R Kneen, B D Michael, E Menson et al. Management of suspected viral encephalitis in children Association of British Neurologists and British Paediatric Allergy, Immunology and Infection Group national guidelines. J Infect. 2012 May;64 5 449 77. Open https://web.pathway.md/diseases/rec48qDhvhP5jAbgq 6/6