CNS Infections - Viral Meningitis and Encephalitis (26) Flashcards Preview

Clinical Pathology > CNS Infections - Viral Meningitis and Encephalitis (26) > Flashcards

Flashcards in CNS Infections - Viral Meningitis and Encephalitis (26) Deck (50):
1

Meningitis

Inflammation of meninges

2

Encephalitis

Inflammation of the brain

3

Meningo-encephalitis

Inflammation of brain and meninges

4

Aseptic meningitis WBC

Above 5X10^6/L in CSF (negative bacterial culture)

5

Common causes of aseptic meningitis

Viruses, partially treated bacterial meningitis, Listeria, TB, syphilis, malignancy, autoimmune conditions, drugs

6

Virion

Basic infectious particle of virus

7

Virus structure

Nucleic acid (DNA/RNA), capsid, lipid envelope (derived from host cell membrane), some contain other proteins/enzymes

8

What is a capsid?

Protein coat, made up of capsomeres (subunits)

9

Epidemiology of viral meningitis

Common neonates and under 5,
5-15 cases per 100,000

10

Aetiology of viral meningitis

- Enteroviruses (echoviruses, coxsackie, parch, enteroviruses 70 and 71, polio)
- Herpes virus (HSV 2), VZV, CMV, EBV, HHV6, HHV7
- Arboviruses
- Mumps
- HIV
- Adenovirus
- Measles
- Influenza
- Parainfluenza type 3
- Lymphocytic choriomeningitis virus (LCMV)

11

What's the lead cause of viral meningitis?

Enteroviruses

12

What are common causes of viral meningitis?

Enterovirus, HSV 2, VZV, Mumps, HIV

13

What percentage of viral meningitis cause unknown?

35%

14

Pathogenesis of viral meningitis

Colonisation of mucosal surfaces, invasion of epithelial surface, replication in cells, dissemination and CNS invasion

15

How does viral meningitis dissemination into CNS?

Via cerebral microvascular endothelial cells, via choroid plexus epithelium, spread along olfactory nerve

16

What are symptoms in VM mainly due to?

Inflammatory response in CNS

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Clinical presentation of viral meningitis

Fever, Meningism (headache, neck stiffness, photophobia), lethargy, myalgia, arthralgia, sore throat, rash, diarrhoea and vomiting

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Children clinical presentation of viral meningitis

Neonates/infants meningeal signs absent, nuchal rigidity/neck stiffness and bulging anterior fontanelle

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Kernig's sign

Hip and knee flexed to 90 degrees, knee cannot be extended due to pain/stiffness in hamstrings

20

Brudzinski's sign

Flexing the neck causes hip and knees to flex

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Nuchal rigidity

Resistance to flexion of the neck

22

Investigations

- Bloods (FBC, U&E, CRP, clotting, blood culture)
- CT (raised ICP, SAH, mass lesion)
- Indicated before LP
- LP (MC&S, protein, glucose, viral PCR)
- Throat swab/stool sample (enterovirus PCR)
- Serology (Mumps, EBV/CMV, HIV)

23

LP contraindications

If raised ICP removing CSF can cause coning (brain though the foramen magnum)

24

CSF findings in viral meningitis/encephalitis

WBC

25

Pleocytosis

WBC in CSF

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Treatment for viral meningitis

IV antibiotics (cefotaxime) if risk of bacterial, supportive therapy, notify public health

27

When do you get epidemics of enteroviral meningitis?

Summer/autumn epidemics

28

Symptoms of enteroviral meningitis

Fever, vomiting, anorexia, rash, upper resp tract symptoms

29

HSV 1 causes

Cold sores and viral encephalitis

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HSV2 causes

Genital herpes and meningitis

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Mollaret's meningitis

Recurrent aseptic meningitis, common cause HSV2

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Primary VZV

Varicella - chickenpox

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Secondary VZV

Zoster - shingles

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Is meningitis common with VZV?

No, it's unusual, can occur during/on its own/after vaccination - rash

35

Mumps meningitis

10-30% mumps cases

36

Symptoms of mumps meningitis

CNS symptoms 5 days after onset of parotitis (parotid gland inflammation), ab pain, orchitis

37

HIV and meningitis

Can occur as part of primary infection

38

HIV and meningitis symptoms

(Glandular fever), fever, lymphadenopathy, pharyngitis, rash (self-limiting)

39

Aetiology of viral encephalitis

- HSV 1, VZV, EBV, CMV
- Adenovirus
- Measles
- Mumps
- Enterovirus (polio)
- Arboviruses (West Nile, Japanese B, St Louis, Eastern and Western Equine Encephalitis)
- Influenza
- Rubella
- HIV
- Rabies
- Bacteria (Step pneumonia, Neisseria meningitidis, TB)
- Malignancy (paraneoplastic)
- Autoimmune
- Acute disseminated encephalomyopathy (ADEM)

40

What are the common causes of viral encephalitis?

HSV1, VZV, EBV, Measles, Mumps, Enterovirus, Bacteria, ADEM

41

What is the most common cause of viral encephalitis?

HSV1

42

What percentage is aetiology unknown in viral encephalitis?

37%

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Clinical presentation of viral encephalitis

Altered mental state (confusion/bizarre behaviour/coma), fever, headache, meningism?, seizures, weakness, dysphasia/aphasia, cranial nerve palsy, ataxia

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Investigations

- Bloods (FBC, U&E, CRP, clotting, cultures, serology)
- CT (before LP)
- MRI (HSV changes)
- LP (M, C&S, protein/glucose, viral PCR)
- EEG (HSV abnormal temporal lobe activity)

45

Treatment of viral encephalitis

High dose IV aciclovir

46

HSE epidemiology

Rare, 50yrs, male=female

47

HSE pathogenesis

Primary infection vs reaction (direct transmission of the virus along neural/olfactory pathways, reactivation in trigeminal ganglia), acute focal necrotising encephalitis, inflammation/swelling of brain tissue

48

Herpes Simplex Encephalitis outcome

Untreated 70% mortality, treated remains high 28% at 18 months,
Paralysis, speech loss, personality change

49

Acute disseminated encephalomyelopathy

Immune-mediated CNS demyelination, can follow viral illness/vaccination, CSF findings= viral meningitis, MRI helpful, treatment - steroids/immunosuppressants

50

If an doubt on diagnosis

Treat as bacteria - antibiotics!

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