eMedicine Specialties > Emergency Medicine > Neurology
Encephalitis: Treatment & Medication
Updated: Jul 16, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Prehospital Care
- Evaluate and treat for shock or hypotension. Administer a crystalloid infusion until the patient is euvolemic.
- Consider airway protection in patients with an altered mental status.
- Consider seizure precautions. Treat seizures according to usual protocol (ie, lorazepam 0.1 mg/kg given intravenously [IV]).
- Stabilize alert patients with normal vital signs by administering oxygen, securing IV access, and providing rapid transport to the ED.
Emergency Department Care
With the important exceptions of HSE and varicella-zoster encephalitis, the viral encephalitides are not treatable beyond supportive care. Treatments for T gondii and CMV encephalitis are available but generally not initiated in the ED.
- The goal of treatment for acutely ill patients is administration of the first dose or doses acyclovir with or without antibiotics or steroids as quickly as possible.
- The standard for acute bacterial meningitis is the initiation of treatment within 30 minutes of arrival.
- Consider instituting an ED triage protocol to identify patients at risk for HSE.
- Collect laboratory samples and blood cultures before the start of IV therapy. Even in uncomplicated cases of encephalitis, most authorities recommend a neuroimaging study (eg, contrast-enhanced head CT scan) before LP.
- Signs of hydrocephalus and increased ICP
- General measures: Manage fever and pain, control straining and coughing, and avoid seizures and systemic hypotension.
- In otherwise stable patients, elevating the head and monitoring neurologic status usually are sufficient.
- When more aggressive maneuvers are indicated, some authorities favor the early use of diuresis (eg, furosemide 20 mg IV, mannitol 1 g/kg IV) provided circulatory volume is protected. Dexamethasone 10 mg IV q6h helps in managing edema surrounding space-occupying lesions. Hyperventilation (PaCO2 30 mm Hg) may cause a disproportional decrease in cerebral blood flow (CBF), but it is used to control increasing ICP on an emergency basis.
- Intraventricular ICP monitoring is controversial because some authorities believe dangerous focal edema with a pressure gradient between the temporal lobe and the subtentorial space usually is not detected by the monitor, leading to a false sense of security. In fact, monitor placement may potentially aggravate a pressure gradient.
- Look for and treat systemic complications, particularly in HSE, EEE, JE, such as hypotension or shock, hypoxemia, hyponatremia (SIADH), and exacerbation of chronic diseases.
- Empiric adult emergency treatment for HSV meningoencephalitis and VZV encephalitis is acyclovir 10 mg/kg (infuse over 1 h) q8h for 14-21 days. Give acyclovir 10-15 mg/kg IV q8h for neonatal HSV; for HSV encephalitis in the pediatric population, give acyclovir 10 mg/kg IV q8h.
- In HIV-positive patients, consider foscarnet, given increased incidence of acyclovir-resistant HSV and HZV.
Consultations
- Neurosurgeon, if brain biopsy is indicated
- Neurologist
- Neonatologist, if indicated
- Infectious disease specialist, if indicated
Medication
The goals of pharmacotherapy are to reduce morbidity and prevent complications.
Antivirals
The goal of the use of antivirals for HSE and varicella-zoster encephalitis is to shorten the clinical course, prevent complications, prevent the development of latency and/or subsequent recurrences, decrease transmission, and eliminate established latency.
Acyclovir (Zovirax)
Has demonstrated inhibitory activity directed against both HSV-1 and HSV-2, and infected cells selectively take it up.
Adult
10 mg/kg (infuse over 1 h) IV q8h for 14-21 d
Pediatric
Neonatal HSV: 10-15 mg/kg IV q8h
HSV encephalitis: 10 mg/kg IV q8h
Coadministration of probenecid, zidovudine, or other nephrotoxic drugs may prolong the half-life, increasing the CNS toxicity of acyclovir
Documented hypersensitivity to acyclovir or related products
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Adjust dose according to CrCl; caution in renal failure or coadministration of other nephrotoxic drugs
Foscarnet (Foscavir)
Organic analog of inorganic pyrophosphate. Inhibits replication of known herpes viruses, including CMV, HSV-1, and HSV-2. Exerts antiviral activity by inhibiting viral replication at pyrophosphate-binding site on virus-specific DNA polymerases at concentrations that do not affect cellular DNA polymerases. Patients with poor clinical response or experience persistent viral excretion during therapy, especially HIV-positive patients, may be resistant to acyclovir. Patients who tolerate foscarnet may benefit maintenance-level administration of 120 mg/kg/d early in treatment. Dosing should be individualized to patient's renal function.
Adult
40 mg/kg IV q8h for 14-26 d
Pediatric
<12 years: Not established
>12 years: Administer as in adults
Because of tendency to cause renal impairment, avoid use in combination with potentially nephrotoxic drugs (eg, aminoglycosides, amphotericin B, IV pentamidine) unless the potential benefits outweigh risks; avoid use with fluoroquinolones; coadministration with IV pentamidine may cause hypocalcemia
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Renal function may decline; to ensure correct dosing, a 24-h serum creatinine level should be determined at baseline and periodically thereafter; discontinue if serum creatinine <0.4 mL/min/kg; hydration may reduce risks of nephrotoxicity; because of propensity to chelate divalent metal ions and alter serum electrolyte levels, carefully monitor electrolytes, including Ca and Mg; as soon as possible, assess for electrolyte abnormalities and mineral levels in patients with mild perioral numbness, paresthesias, or severe symptoms (eg, seizures); to permit rapid dilution and distribution and to avoid local irritation, infuse solution only into veins with adequate blood flow; relatively high incidence of granulocytopenia and anemia; important to monitor CBCs regularly; do not administer by rapid or bolus IV injection; toxicity may be increased as a result of excessive plasma levels
Corticosteroids
Anti-inflammatory agents used for treatment of postinfectious encephalitis and acute disseminated encephalitis. These drugs are commonly presented as treatment alternatives, though supporting data are limited.
Dexamethasone (Decadron, Dexasone)
Used to treat various allergic and inflammatory diseases. May decrease inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Adult
10 mg IV q6h
Pediatric
0.15 mg/kg IV q6h
Barbiturates, phenytoin, and rifampin can decrease effects; decreases effect of salicylates and vaccines
Documented hypersensitivity, active infection, fungal infection
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Monitor for adrenal insufficiency when drug is tapered; patients receiving glucocorticoids are at risk for multiple complications, including severe infections; abrupt discontinuation may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections are possible complications
More on Encephalitis |
| Overview: Encephalitis |
| Differential Diagnoses & Workup: Encephalitis |
 Treatment & Medication: Encephalitis |
| Follow-up: Encephalitis |
| References |
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Further Reading
Keywords
encephalitis, West nile virus, cerebritis, acute encephalitis, herpes simplex encephalitis, HSE, varicella-zoster encephalitis, VZ encephalitis, West Nile encephalitis, St Louis encephalitis, SLE, California virus encephalitis, LaCross encephalitis, eastern equine encephalitis, western equine encephalitis, Powassan virus, Japanese virus encephalitis, JE, arboviral JE, subacute encephalopathies, chronic encephalopathies, acute arboviral encephalitides, acute viral encephalitides, cytomegalovirus encephalitis, CMV encephalitis, sclerosing panencephalitis, progressive multifocal leukoencephalopathy, HSV Cowdry type A inclusions, acute disseminated encephalitis, postinfectious encephalomyelitis, Epstein-Barr virus, EBV encephalitis, subacute sclerosing panencephalitis, rabies encephalitis, acute disseminated encephalitis, stiff neck, photophobia, lethargy, toxoplasma encephalopathy, meningismus
