This document discusses encephalitis, which is inflammation of the brain. It can be caused by primary infection of the brain by viruses or secondary spread from other areas of the body. Common causes include herpes simplex virus, arboviruses like West Nile, and childhood viruses. Clinical presentation involves headache, fever, seizures, and altered mental status. Diagnosis involves imaging like CT or MRI of the brain and lumbar puncture to examine CSF. Treatment involves antivirals for viral causes as well as supportive care. Complications can include epilepsy, cognitive impairment, paralysis, and death.
2. Introduction;Definition
• Encephalitis is the inflammation of brain.
• It can be ;
• Primary encephalitis –virus directly infects the brain and spinal cord.
• Secondary encephalitis –Infection starts elsewhere in the body and
then travels to the brain.
3. Causes;
• a)Common viruses- includes Herpes simplex, mumps, Epstein Barr
Viru, HIV, Cytomegalovirus.
• b)Childhood viruses – includes Chicken pox, measles, rubella etc.
• c)Arboviruses – includes California virus, S.t Lous virus, West Nile
virus, Colorado virus etc.
4. Viral encephalitis;
• Commonest cause is Herpes simplex.
• Also arboviruses.
• Risk factors include;old age, children and immunocompromised
patients like HIV/AIDS.
5. Pathophysiology;
• Infection provokes an inflammatory response.
• Involves cortex, white matter, basal ganglia, and brainstem.
• Distribution of lesions varies.
• In Herpes simplex, temporal lobes are affected.
• In Cytomegalovirus, areas adjacent to ventricles are affected
(ventriculitis).
• Inclusion bodies present in neurons and glial cells.
• Infiltration of polymorphonuclear cells in perivascular space.
• Also, neuronal degeneration and diffuse glial proliferation.
6. Clinical presentation;
• Acute onset of headache, fever, focal neurological signs like
aphasia, hemiplegia, and visual field defect.
• Seizures, altered level of consciousness.
• Coma
• Meningism may also occur. Involves; neck stiffness, photophobia,
nausea and vomiting.
• In children,it presents with vomiting, bulging fontanel, constant
cough, body stiffness and poor appetite.
• Also, behavioral changes may occur.
7. Clinical features ;continued
• In severe cases;
• Drowsiness
• Hallucination
• Prostrations
• Coma
• Seizures
• Irritability
• Photophobia
• Difficulties in speaking
8. Diagnosis;
• Imaging tests include;
• CT scan of the head – shows low density lesions in temporal
lobes.
• MRI – more sensitive and can reveal early abnormalities.
• Lumber puncture; CSF examination;
• Excess lymphocytes, normal glucose level….
• Also, PCR can reveal the cause.
• Electroencephalography; abnormal in early stages.
9. Diagnosis criteria;
• Major criteria; Subacute onset of consciousness impairment,
impaired memory, mental status and also new onset of
psychiatric changes without alternative cause.
• Minor criteria;
• 1.Fever > 38 * C within 72 hrs before and after presentation.
• 2.Seizures
• 3.CSF pleocytosis
• 4.Evidence of brain parenchyma inflammation on neuroimaging.
12. Management,continued;
• Specific treatment;
• Antivirals, especially Aciclovir 10 mg/kg TID for 21 days IV in
cases of Herpes simplex.
• Dexamethasone in raised intracranial pressure.