Encephalitis due to human herpes simplex virus

Encephalitis due to human herpes simplex virus - Acute
Rahul Soman, M. Pharm

 

Definition  

An acute, focal, necrotizing encephalitis with inflammation and swelling of the brain caused by herpes simplex virus (HSV) type 1 or type 2

 

Medical History  

* Herpes simplex [Herpes simplex - Acute]

 

Findings  

* Decreased level of consciousness - Acute

* Fever

* Headache

* Personality change

* Seizure

* Ataxia

* Hemiparesis

* Cranial nerve disorder

* Asthenia

* Aphasia

* Visual field defect

* Sensory disorder

* Vomiting

* Irritability

* Tremor

* Feeding problems in newborn

* Bulging fontanelle

 

Tests  

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 encephalitis  

* Cerebrospinal fluid examination: In herpes simplex encephalitis, the cerebrospinal fluid often shows lymphocytic pleocytosis, mildly elevated protein , and normal glucose levels .

 

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 herpes simplex encephalitis  

* Biopsy of brain tissue

 

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 herpes virus infection of the central nervous system  

* Herpes simplex virus culture: Herpes simplex virus (HSV) culture of cerebrospinal fluid is only useful in patients less than 6 months of age with suspected herpes simplex viral infection of the CNS .

 

Differential Diagnosis  

* Viral encephalitis - Acute

* Abscess of brain - Acute

* Encephalopathy

* Meningitis

* Disseminated encephalomyelitis, acute

* Vascular disorder

* Intracranial tumor

* Subdural hematoma - Acute

* Adrenoleukodystrophy

* Systemic lupus erythematosus

 

Treatment  

 

Drug Therapy  

 

Suspected or known herpes simplex encephalitis  

 

ACYCLOVIR

Adults: 10 mg/kg IV every 8 hours for 14 to 21 days

Pediatrics: 10 mg/kg IV every 8 hours for 14 to 21 days

Neonates: 20 mg/kg IV every 8 hours for 21 days

 

 

Acute control of focal or generalized seizures  

 

LORAZEPAM  

Adults: 4 mg IV at rate of 2 mg/minute; may repeat dose in 10 to 15 minutes if needed

Pediatrics: 0.05 to 0.1 mg/kg IV over 2 to 5 minutes; may repeat one time in 10 to 15 minutes at 0.05 mg/kg

Neonates: 0.05 to 0.1 mg/kg IV over 2 to 5 minutes; may repeat one time in 10 to 15 minutes at 0.05 mg/kg

 

PHENOBARBITAL SODIUM  

Adults: 100 to 320 mg slow IV injection, not to exceed 600 mg/24 hours

Pediatrics: 15 to 20 mg/kg IV; may give additional doses of 5 mg/kg every 15 to 30 minutes to a maximum total dose of 30 mg/kg

Neonates: 20 mg/kg IV; follow with additional IV boluses of 5 mg/kg to a maximum total of 40 mg/kg

 

FOSPHENYTOIN SODIUM  

Adults: 15 to 20 mg/kg IV, slowly at 150 mg/minute

Pediatrics: 15 to 20 mg/kg IV, slowly at 3 mg/kg/minute, maximum 150 mg/minute

Neonates: 20 mg/kg IV

 

PHENYTOIN SODIUM  

Adults: 15 to 20 mg/kg IV, slowly at 150 mg/minute

Pediatrics: 15 to 20 mg/kg IV, slowly at 3 mg/kg/minute, maximum 150 mg/minute

 

Increased intracranial pressure  

 

MANNITOL  

Adults: 0.25 to 1 g/kg IV over 20 to 30 minutes; may repeat in 6 hours; maximum 6 g/kg/24 hours

Pediatrics: 0.25 g/kg IV over 20 to 30 minutes; may gradually increase to 1 g/kg/dose if needed

 

Procedural Therapy  

 

Increased intracranial pressure  

* Intracranial pressure monitoring: Cerebral perfusion is assessed by monitoring the intracranial pressure, cerebral perfusion pressure, cerebral blood flow, and brain tissue PO2.

 

Increased intracranial pressure  

* Decompression of brain: Mechanical decompression of the brain can be lifesaving when performed in a timely fashion in patients with herniation secondary to cerebral edema .