eMedicine Specialties > Neurology > Neurological Infections
Herpes Simplex Encephalitis: Treatment & Medication
Updated: Sep 2, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Medical Care
- General nutritional and fluid support is important. Universal precautions are appropriate. Monitor for increased intracranial pressure and seizures.
- Increased intracranial pressure
- Treatment of brain edema ranges from simple measures (eg, elevating head of bed, gentle diuresis with medication such as furosemide) to more complex measures (eg, mannitol and steroids, intubation with hyperventilation).
- Seizures
- Behavioral manifestations of HSE may resemble seizures, which are also common.
- Should seizure activity become apparent or should the EEG show evidence of nonconvulsive seizures, begin anticonvulsant therapy.
- Benzodiazepines may be useful for aborting status epilepticus but, because of their short duration, are ineffective at preventing further seizures.
- A longer-acting agent is preferable.
Surgical Care
When HSE diagnosis cannot be established, brain biopsy can yield definitive diagnosis. Biopsy may be considered when lumbar puncture is precluded or nondiagnostic but is rarely used today with the availability of nontoxic and effective antiviral medications.
Consultations
- HSE is a neurologic emergency. Consultation with a neurologist is required.
- Neurosurgical consultation is helpful only if a brain biopsy is being considered.
- An infectious disease consultation may be appropriate.
- An evaluation for rehabilitation is often appropriate to deal with the long-term neurological sequelae of HSE.
Medication
The goals of therapy are to reduce morbidity and to prevent complications.
Pharmacotherapy for HSE is available in the form of acyclovir and vidarabine.
Patient outcome is improved when treated with either of these agents. Acyclovir is more effective and less toxic.
When the diagnosis of HSE is suspected or has been established, IV acyclovir should be initiated immediately.
A 2009 Cochrane database review pulled data from 17 trials that compared interventions used for the prevention and treatment of herpes simplex virus in patients being treated for cancer. The authors concluded that aciclovir is effective in preventing and treating herpes simplex virus infections. Valaciclovir was not found to be more effective than aciclovir, nor did a higher dose of valaciclovir make a difference. Some evidence indicated that placebo, as a prophylaxis, is more effective than prostaglandin E, but the risk of bias was unclear in all trials.15
Antivirals
The goals of using antivirals are to shorten the clinical course, prevent complications, prevent development of latency and subsequent recurrences, decrease transmission, and eliminate established latency.
Acyclovir (Zovirax)
Has demonstrated inhibitory activity against both HSV-1 and HSV-2 and is taken up selectively by infected cells; rate of mortality from HSE before use of acyclovir was 60-70%—since acyclovir, it is approximately 30%.
Adult
10 mg/kg/dose IV or 500 mg/m2/dose IV q8h
Pediatric
Administer as in adults
Half-life prolonged and toxicity increased by concomitant probenecid or zidovudine
Documented hypersensitivity
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Use caution in patients with renal failure or receiving other nephrotoxic drugs concurrently
Anticonvulsants
These agents are used to terminate clinical and electrical seizure activity as rapidly as possible and prevent seizure recurrence.
Carbamazepine (Tegretol)
Effective in treatment of complex partial seizures; appears to act by reducing polysynaptic responses and blocking posttetanic potentiation.
Once a response is attained, attempt to reduce dose to minimum effective level or to discontinue drug at least once q3mo.
Adult
200 mg PO bid or 100 mg suspension PO qid; increase at weekly intervals by no more than 200 mg/d tid/qid (bid with extended release) until best response obtained; not to exceed 1600 mg/d
Pediatric
<6 years: 10-20 mg/kg/d PO bid/tid (qid with suspension); increase weekly to achieve optimal clinical response administered tid/qid
6-12 years: 100 mg PO bid or 50 mg suspension PO qid; increase at weekly intervals by gradually adding another 100 mg/d on tid/qid schedule (bid with extended release) until best response obtained; not to exceed 1000 mg/d
>12 years: Administer as in adults; not to exceed 1000 mg/d in children aged 12-15 y or 1200 mg/d in patients >15 y
May decrease primidone and phenobarbital levels; serum concentrations may be increased by concurrent primidone or phenobarbital; plasma levels and toxicity may increase with concurrent cimetidine—interaction of greatest clinical importance when cimetidine added to carbamazepine during first 4 wk of therapy; levels increase 38-123% within 30 d of danazol administration
Documented hypersensitivity, history of bone marrow depression, concomitant MAOIs, concomitant danazol
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Do not use concomitantly with MAOIs; discontinue MAOIs for >14 d before carbamazepine administration
This drug is not a simple analgesic; do not use for relief of minor aches or pains; use caution in patients with increased intraocular pressure
Obtain complete pretreatment blood counts, including platelets and possibly reticulocytes and serum iron, as baseline; monthly CBC, differential, platelets during the first 2 mo and thereafter yearly or every other year
May produce drowsiness, dizziness, or blurred vision; patients should observe caution while driving or performing other tasks requiring alertness, coordination, or physical dexterity
Phenytoin (Dilantin)
A hydantoin, its primary site of action appears to be motor cortex, where it may inhibit spread of seizure activity; may reduce maximal activity of brain stem centers responsible for tonic phase of grand mal seizures.
Dose should be individualized; if daily dosage cannot be divided equally, larger dose should be given before bedtime.
Phosphorylated formulation, fosphenytoin, available for parenteral use (IV/IM).
Adult
Initial: 100 mg PO/IV tid or 125 mg suspension PO tid
Maintenance: 300-400 mg/d PO/IV divided tid (qd/bid if extended release); increase to 600 mg/d (625 mg/d suspension) prn; not to exceed 1500 mg/d
Pediatric
Initial: 5 mg/kg/d PO/IV divided bid/tid
Maintenance: 4-8 mg/kg PO/IV divided bid/tid; not to exceed 300 mg/d
> 6 years: May require minimum adult dose (300 mg/d); not to exceed this dose
Toxicity may be increased by amiodarone, benzodiazepines, chloramphenicol, cimetidine, disulfiram, ethanol (acute ingestion), fluconazole, isoniazid, metronidazole, miconazole, omeprazole, phenacemide, phenylbutazone, succinimides, sulfonamides, trimethoprim, and valproic acid; effects may be decreased by barbiturates, carbamazepine, diazoxide, ethanol (chronic ingestion), rifampin, theophylline, antacids, charcoal, and sucralfate; may decrease effects of acetaminophen, amiodarone, carbamazepine, cardiac glycosides, corticosteroids, dicumarol, disopyramide, doxycycline, estrogens, haloperidol, methadone, metyrapone, mexiletine, oral contraceptives, quinidine, theophylline, and valproic acid
Documented hypersensitivity; SA block, sinus bradycardia, second- and third-degree AV block, Adams-Stokes syndrome (because of effects on ventricular automaticity)
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Death from cardiac arrest has occurred after too-rapid IV administration, sometimes preceded by marked QRS widening; discontinue if hepatic dysfunction occurs; discontinue if skin rash appears—do not resume if rash is exfoliative, bullous, or purpuric; use caution in patients with diabetes (may raise blood glucose) or acute intermittent porphyria
May cause blood dyscrasias; obtain baseline CBC and urinalysis, repeat monthly for several months thereafter
More on Herpes Simplex Encephalitis |
| Overview: Herpes Simplex Encephalitis |
| Differential Diagnoses & Workup: Herpes Simplex Encephalitis |
 Treatment & Medication: Herpes Simplex Encephalitis |
| Follow-up: Herpes Simplex Encephalitis |
| References |
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Further Reading
Keywords
herpes, genital herpes, herpes encephalitis, encephalitis, HSE, HSV-1, HSV-2, cold sores, fever blisters, herpes simplex virus, human herpesvirus, HHV, HHV-1, herpes simplex virus type 1, herpes simplex virus type 2, herpes simplex encephalitis
