Viral encephalitis - Acute
Definition
An acute viral infection of the brain parenchyma causing an inflammatory process in association with clinical evidence of neurologic dysfunction
Medical History
* Adult, Geriatric (>65 years)
* Pediatric (0-18 years)
* Neonate (<30 days and 37 weeks of gestation or more)
* Mosquito bite
* Tick bite
* Occupational Exposure
* Outdoor Recreational Activities
* Animal Contact
* Travel
* Past medical history of Inadequate immune status
* Infection after transfusion, Transfusion of blood product
* Patient immunocompromised and Immunodeficiency disorder
* Disorder related to transplantation, Transplantation
Findings
* Fever
* Headache
* Altered mental status
* Nuchal rigidity
* Viral exanthem
* Lymphadenopathy - Acute
* Disturbance in speech
* Seizure
* Nausea and vomiting - Acute
* Myalgia
* Mosquito bite
* Pharyngeal erythema
* Respiratory finding
* Fatigue
* Diarrhea
* Muscle weakness
* Tick bite
* Focal neurological signs
* Impaired cognition
* Personality change
* Amnesia
* Abnormal movement
* Backache
* Dizziness
* Abdominal pain - Acute
* Splenomegaly
* Radicular pain
* Muscle rigidity
* Altered behavior
* Hallucinations
* Cranial nerve disorder
* Facial palsy
* Hemiparesis
* Hemiplegia
* Neurological muscular paralysis
* Pyramidal sign
* Retinitis
* Diplopia
* Photophobia
* Nystagmus
* Ophthalmoplegia
* Optic disc swelling
* Impairment level of vision
* Parotid swelling
* Sensorineural hearing loss
* Dysuria
* Urgent desire to urinate
* Urinary incontinence
Tests
Evaluation for bacterial and fungal etiologies of encephalitis
* Blood culture
Suspected viral encephalitis
* MRI of head: MRI is a valuable procedure for the early detection of viral encephalitis and in some cases may help to differentiate specific etiologies .
Suspected viral encephalitis
* Cerebrospinal fluid examination: Cerebrospinal fluid analysis in patients with viral encephalitis typically shows lymphocytic pleocytosis, normal or mildly elevated protein, normal glucose, and negative Gram staining .
Viral encephalitis
* Polymerase chain reaction analysis, Cerebrospinal fluid
Suspected bacterial meningitis
* Cerebrospinal fluid culture: Bacterial culture of the cerebrospinal fluid is critical in making the diagnosis of bacterial meningitis, identifying the causative organism, and selecting the appropriate antibiotic treatment regimen .
Suspected viral encephalitis
* Electroencephalogram: EEG may show cerebral involvement early in the course of encephalitis and is important in detecting nonconvulsive seizures in patients with mental status changes .
Suspected herpes simplex encephalitis
* Herpes simplex virus DNA assay: A positive polymerase chain reaction test for herpes simplex virus (HSV) in cerebrospinal fluid is generally diagnostic of HSV encephalitis .
Suspected herpes simplex encephalitis
* Herpes simplex virus 1 AND 2 antibody assay: Tests of cerebrospinal fluid for herpes simplex virus (HSV) antibodies may be useful after a week of therapy for HSV encephalitis, but HSV polymerase chain reaction (PCR) is recommended for diagnosis .
Suspected and known herpes simplex encephalitis
* Magnetic resonance imaging of brain and brain stem: A cranial MRI showing a hemorrhagic encephalitis affecting the temporal and inferior frontal lobes strongly suggests herpes simplex virus encephalitis .
Suspected or known herpes simplex encephalitis
* Computerized axial tomography of brain: Although the brain CT may be normal early in the course of herpes simplex encephalitis, typical findings include lesions in one or both temporal lobes .
Suspected herpes simplex virus encephalitis
* Electroencephalogram: An EEG done early in the course of herpes simplex encephalitis may reveal periodic lateralized epileptiform discharges localized to the temporal lobes .
Suspected arboviral encephalitis
* Encephalitis viral serology test: A 4-fold or greater change in virus-specific antibody levels between acute and convalescent sera in the appropriate clinical setting is confirmatory for arboviral encephalitis .
Suspected or known West Nile virus disease, including encephalitis
* West Nile virus antibody assay: A 4-fold or greater change in virus-specific serum antibody levels is confirmatory for West Nile virus infection .
Suspected viral encephalitis
* Electromyography: Electromyography may show significant abnormalities in viral encephalitis .
Differential Diagnosis
* Bacterial meningitis - Acute
* Bacterial encephalitis
* Viral meningitis - Acute
* Fungal infection of central nervous system
* Parasitic encephalitis
* Intracranial abscess
* Subdural hematoma - Acute
* Vascular disorder
* Encephalopathy
* Disseminated encephalomyelitis, acute
* Disease due to JC polyomavirus
* Rabies - Acute
* Encephalitis due to human herpes simplex virus - Acute
* West Nile encephalitis
* Enterovirus infection of the central nervous system
* Encephalitis due to Herpesviridae
* Arbovirus encephalitis
* Measles of the central nervous system
* Mumps encephalitis
* Rubella encephalitis
* Adenoviral encephalitis
* Encephalitis due to influenza
Treatment
Drug Therapy
All cases of suspected viral encephalitis while awaiting diagnostic lab results
ACYCLOVIR
Adults: 10 mg/kg IV every 8 hours
Neonates: 20 mg/kg IV every 8 hours
Pediatrics: 10 mg/kg IV every 8 hours
Herpes simplex encephalitis
ACYCLOVIR
Adults: 10 mg/kg IV every 8 hours for 14 to 21 days
Neonates: 20 mg/kg IV every 8 hours for 21 days
Pediatrics: 10 mg/kg IV every 8 hours for 14 to 21 days
Cytomegalovirus (CMV) encephalitis
GANCICLOVIR SODIUM - FOSCARNET SODIUM
Adults: Ganciclovir 5 mg/kg IV every 12 hours AND foscarnet [60 mg/kg IV every 8 hours OR foscarnet 90 mg/kg IV every 12 hours] for 3 weeks, followed by maintenance therapy
Varicella zoster virus (VZV) encephalitis
ACYCLOVIR
Adults: 10 to 15 mg/kg IV every 8 hours for 10 to 14 days
Possible treatment option in immunocompromised patients with human herpesvirus 6
GANCICLOVIR SODIUM - FOSCARNET SODIUM
Adults: Ganciclovir 5 mg/kg IV every 12 hours AND foscarnet [60 mg/kg IV every 8 hours OR foscarnet 90 mg/kg IV every 12 hours]
Procedural Therapy
Refractory cerebral edema or impending uncal herniation
* Decompression of brain
Increased intracranial pressure
* Introduction of intracranial pressure measuring device
Reportable infectious diseases
* Infectious disease notification: In the United States, specific infectious diseases must be reported to the state or local public health department .
