Meningo-Encephalitis/Encephalitis, Acute Viral

Description

General and supportive measures

Medicine treatment

Referral

---

ICD-10 code: A86

DESCRIPTION

A number of viruses cause infection of the brain and meninges. Herpes simplex is the most important because it is treatable. A high mortality and morbidity is associated with untreated herpes meningo-encephalitis.

Complications include:

• increased intracranial pressure,
• permanent neurological deficits,
• cerebral oedema,
• seizures,
• blindness,
• deafness,
• inappropriate antidiuretic hormone (ADH) secretion.

Clinical

• Severe headache, fever, nausea, vomiting, lethargy and abnormal behaviour.
• Alteration in level of consciousness, i.e. drowsiness, confusion, stupor or coma.
• Generalised and/or focal convulsions.
• Focal neurological deficits.
• Abnormal movements, i.e. basal ganglia involvement.
• Cranial nerve palsies (brainstem involvement), loss of sphincter control, paresis of limbs and segmental sensory loss (spinal cord involvement).
• Some patients may have signs of meningeal irritation.
• Herpes encephalitis may have an acute and fulminant course. It can result from primary infection or reactivation.
• Herpetic skin lesions are usually NOT present in children with HSV encephalitis.

Investigations

• Laboratory tests are important in excluding bacterial, fungal or TB meningitis.
• CSF & blood for HSV PCR if the diagnosis is suspected.
• CSF may be normal or reveal:
  • mildly raised protein,
  • normal glucose level, and
  • mild pleocytosis, mostly lymphocytes.
  • Red cells are commonly observed with herpes encephalitis.
• CT brain, if focal signs or seizures, unexplained reduced level of consciousness, status epilepticus or diagnostic uncertainty.
  • May reveal oedema.
  • Herpes simplex preferentially involves the temporal lobes and orbital surfaces of the frontal lobes.
  • CT findings may only be apparent after 3–5 days.
• EEG, if focal or prolonged seizures, diagnostic uncertainty, suspected non-convulsive seizures.
  • May demonstrate changes suggestive of herpes encephalitis.

GENERAL AND SUPPORTIVE MEASURES

• Admit to a high or intensive care unit, if appropriate.
• Monitor, where indicated:
  • neurological status,
  • respiration,
  • heart rate,
  • body temperature,
  • blood pressure,
  • electrolytes,
  • haematocrit,
  • blood glucose,
  • acid-base status,
  • blood gases,
  • fluid balance, i.e. hydration,
  • serum and urine osmolarity.
  • Ensure adequate nutrition, nasogastric feeding if necessary.
  • If enteral feeding is not possible, give maintenance intravenous fluids.

MEDICINE TREATMENT

If herpes simplex virus or varicella zoster virus encephalitis suspected:

• Aciclovir, IV, 8 hourly administered over 1 hour.
  If 0–12 years of age: 20 mg/kg/dose.
  If > 12 years of age: 10 mg/kg/dose.
  • Herpes simplex: 14 days.
  • Varicella: 7 days.
  • If an alternative diagnosis is made and CSF PCR is negative, stop acyclovir.

---

Note:
CSF PCR may be negative in the first 3 days of illness.

---

Acute convulsions

See: Status Epilepticus (Convulsive).

Provide adequate analgesia. See: Pain Control.

Raised intracranial pressure or cerebral oedema

Elevate head of bed ~ 30°.
Maintain P_aCO₂ at 4–5 kPa; intubate and ventilate, if necessary.
Avoid fluid overload.

• Mannitol, IV, 250 mg/kg administered over 30–60 minutes.
  • Do not repeat without consulting a paediatrician.

REFERRAL

• Deterioration of clinical condition despite adequate treatment.
• Meningo-encephalitis with complications or loss of consciousness.

Click here for the pdf.

---

Standard Treatment Guidelines and Essential Medicines List for South Africa Paediatric Hospital _2023, 5th edition_Updated July 2024 

Chapter 8: Infective/Infectious Diseases,  8.13 Meningo-encephalitis/encephalitis, Acute Viral