Viral Meningitis / Encephalitis (CNS Pathology) Flashcards
What is Meningitis?
Inflammation of the meninges
What is Encephalitis?
Inflammation of the brain
What is Aseptic Meningitis?
Is the inflammtion of the meninges however it is not caused by bacteria. Viruses are usually the cause e.g.syphilis
What is the stucture / components of a virus?
Nucleic Acid:
- DNA or RNA
- Single or double stranded
- circular or linear
Viral Proteins:
-form capsid / membrane projections.
Viral Enzymes:
- replication
- transcription
- protein modification
What is the epidemiology of Viral Meningitis?
-common is children
What are the causes of Viral Meningitis?
1) Enteroviruses
2) Herpes Viruses
3) Mumps
4) HIV
5) Measles
6) Influenza
How do these pathogens cause meningitis?
1) COLONISE on mucosal surfaces
2) ENTER epithelial surface
3) REPLICATE in cells
4) spread and INVADE CNS
What are the clinical features of Meningitis
1) Fever
2) Meningism
- headache
- neck stiffness
- photophobia
***3) bulging anterior fontanelle (top of skull) in infants
What is Kernig’s Sign?
When the hip and knee are both flexed to 90’ the knee cannot be extended further due to pain / stiffness in hamstrings. It is a sign of meningitis.
What is Brudzinki’s sign?
Flexing the neck causes the hips and knees to flex.
What investigations should be done for meningtis?
- Lumbar puncture ASAP alongside blood glucose levels.
- CT scan (raised intracranial pressure)
What are the CSF findings in viral meningitis?
- White Cell count (lymphocytic, neutrophils)
- Protein (0.2 - 0.4 g/L)
- Glucose ratio normal or low.
What is the treatment of meningitis?
-IV antibiotics (if bacterial)
what is the commonest cause of viral meningitis in the uk?
What are the symptoms?
Enteroviral
Symptoms:
-fever, vomiting, anorexia, rash, respiratory tract problems
Which form of Herpes Simplex Virus (HSV) causes meningitis?
HSV2 = meningitis + genital herpes
HSV1 = Encephalitis + cold sores
What virus causes chickenpox & shingles ?
Varicella Zoster Virus
What are the symptoms of mumps meningitis?
CNS symptoms 5days after onset of parotitis (inflammation of parotid gland)
Whats are the associated features of HIV meningitis?
- fever
- lymphadenopathy
- pharyngitis
- rash
What are the causes of Viral Encephalitis?
1) Herpes Simplex Virus (HSV1)
2) Varicella Zoster Virus
3) Measles
4) Mumps
5) Enteroviruses
6) Influenza
7) Rubella
8) HIV
What are the bacterial cause of encephalitis?
1) Strep pneumoniae
2) Neisseria meningitidis
3) TB
What are the clinical features of Encephalitis?
1) Altered mental state (confusion, bizaare behaviour)
2) Fever, headache
3) seizures
What are the investigations for encephalitis?
1) CT
2) MRI *may see changes typical of HSV encephalitis
3) Lumbar Puncture
4) EEG *HSV will show abnormal temporal lobe activity
5) bloods
What are the CSF findings in viral encephalitis?
*same as in viral meningitis
1) White cell count
- Lymphocytic
2) Protein mildy elevated
3) Glucose ratio is normal or slightly low.
What is the treatment for viral encephalitis?
High dose of IV Aciclovir
How does Herpes Simplex virus cause (HSE) Encephalitis?
*Medical emergency
The virus directly transmitted along neural pathways.
It resides in the trigeminal ganglia.
what is Acute disseminated encephalomyelopathy (ADEM)
Immune mediated CNS DeMyelination
- can follow viral illness
- clinical features same as encephalitis
- CSF findings same as viral meningitis.
- treatment = steroids /immunosuppressants
