L38 Viral infections of CNS Flashcards
For acute meningitis, what are the causative viruses? (4)
- Enterovirus
- HSV-2
- VZV
- Parechovirus
For acute encephalitis, what are the causative viruses? (5)
What are the type of encephalitis they cause respectively?
A. HSV-1, HSV-2,HHV6
- Focal encephalitis
B: Rabies, Japanese encephalitis virus
- Pan-encephalitis
For acute myelitis (spinal cord), what are the causative viruses? (2)
- Poliovirus
2. Enterovirus RV71, usually hand food mouth disease
For acute tropical spastic paraparesis, what is the causative organism?
HTLV-1
- progressive demyelination of long motor neurone tracts in spinal cord
What are the routes of CNS entry of virus?
- Hematogenous
- infected macrophages/lymphocytes as “Trojan horse”, e.g. JEV - Reactivation: from latency, e.g. herpesvirus
- Neural: via peripheral nerve, e.g. rabies
What is the definition of acute viral encephalitis?
Inflammation of the brain parenchyma
Which has a more insidious symptoms? Meningitis or encephalitis?
encephalitis
What is the most common cause for a viral encephalitis?
- sporadic, no seasonality
a) in neonates
b) in children and adults?
Herpes virus simplex
a) primary infection of HSV-2
b) reactivation of HSV-1
Patient presents with low grade fever, confusion, seizures and dysphagia and has progressed to meningoencephalitis.
What are the investigations along the time line of 2 weeks?
- D-0 Check neurological signs and symptoms
- CSF for HSV PCR
- D-7 MRI/CT scan /EEG
- D-14 Intrathecal HSV antibody
What is the most important thing to see in CSF in a patient with suspected encephalitis?
HSV PCR
since
- HSV Ab >10 days to develop
- Antigen detection and viral culture is insensitive (too few cells are present)
What is the treatment for herpes simplex encephalitis?
What are the side effects of overdose of that drug? (2)
Acyclovir IV 10-15 mg/kg Q8h empirically until PCR result is available, for at least 3 weeks when confirmed
OD side effects (esp. in elderly)
- Encephalopathy
- Nephropathy: ensure adequate hydration
Rabies virus is neurotrophic. List some the animal sources?
- Dogs
- Raccoons
- Bats
etc.
Clinical features of rabies encephalitis?
o _________ period: depending on the site of wound bite; 2w – 3m, up to years
o Prodromal stage: _________, ___________ around the wound site
o Acute neurologic syndromes
Incubation;
fever, paraesthesia
Name 2 acute neurological syndromes of rabies encephalitis.
- Encephalitic: hydrophobia (fear of water due to throat muscle spasm during swallowing), photophobia, delirium
- Paralytic: flaccid paralysis (fun fact: some are misdiagnosed as GBS)
Rabies encephalitis is fatal. T/F?
True!
Coma > death due to cardio-respiratory arrest.
Prevention of rabies encephalitis? (3)
- Pre-exposure prophylaxis: inactivated rabies vaccine
- Post-exposure prophylaxis: vaccine + rabies hyperimmune globulin (HRIG)
- Veterinary measure: inactivated rabies vaccine to dogs/ cats
What is hyperimmune globulin for post-exposure prophylaxis of rabies encephalitis?
Prepared from plasma of donors with high titre of antibody against an organism
Name the acute viral myelitis you know.
What is the pathogenic pathway?
Presentation?
Poliomyelitis. (caused by poliovirus 1-3)
- direct infection of the anterior horn cells of the spinal cord
- fever, flaccid paralysis
What is the vaccine given for poliovirus infection?
- inactivated vaccine
- oral live vaccine too
Post-exposure syndrome of a viral infection:
- Immune-mediated disease as a result of infection/exposure to virus
- culprit virus may not be neurotrophic and virus cannot be isolated from CSF/brain tissue
Give 3 examples.
- Post-infectious encephalomyelitis
- Guillain-Barre syndrome
- Reye’s syndrome
_________________ occur during convalescent phase of certain viral infections or vaccination:
• Measles, mumps, rubella
• VZV
• Influenza
Post-infectious encephalomyelitis
Post-infectious encephalomyelitis:
- ___________ caused : exposure to foreign Ag that closely resemble host proteins on tissues of brain & spinal cord > ____________
- CNS affected: permanent neurological deficits
Autoimmune;
widespread demyelination
In GBS, what is the characteristic feature?
- Cause?
- no specific treatment, but resolve spontaneously over weeks-months.
Ascending paralysis - PNS affected, associated with parasthesia
- Occur days-weeks after acute phase of viral/ bacterial infection/ post-vaccination (rare)
Reye’s syndrome is a post-infectious encephalopathy.
Associated with?
What are the common presentations? (2)
- Following viral infection (e.g. influenza, chicken pox), associated with use of aspirin
- Cerebral oedema, fatty liver
Chronic viral infection of the CNS is rare.
What is the disease that issue to persistent measles infection in CNS?
Subacute-sclerosing panencephalitis (SSPE) *Sketchy!!
- measles virus remains and replicate in brain > damage
- slow, progressive degeneration of the brain over 6-8 years
Progressive multifocal leukoencephalopathy (PML)
is the reactivation of ____________ virus in brain.
This viral infection is common, but only in _____________ causing neurological diseases.
JC virus
- AIDS and immunocompromised
Subacute spongioform encephalopathy is related to _________disease?
Creutzfeldt-Jakob disease (Mad cow disease)
