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B3 CTB > Infections of the Nervous System > Flashcards

Infections of the Nervous System Flashcards

1
Q

Where is intracranial pressure most easily measured?

A

Lumbar spine.

Done via a lumbar puncture and measurement of opening pressure.

Accurate if there are no blockages in CSF circulation.

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2
Q

What is meningoencephalitis?

A

Inflammation of the meninges and brain.

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3
Q

What is myelitis?

A

Inflammation of the spinal cord.

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4
Q

What is a cerebral abscess?

A

A collection of pus in the brain.

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5
Q

What is an epidural/ subdural abscess?

A

Pus in the epidural/subdural space.

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6
Q

Give 6 bacterial causes of meningitis.

A
  • Neisseria meningitidis (meningococcus).
  • Streptococcus pneumoniae (pnumococcus).
  • Groub B Streptococci.
  • Haemophilus influenzae type B (HiB).
  • Listeria monocytogenes.
  • Mycobacterium tuberculosis.
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7
Q

Give 5 viral causes of meningitis.

A

Enterovirus

VZV

HIV

Mumps

Measles

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8
Q

Give a fungal cause of meningitis.

A

Cryptococcus neoformans.

Common in people with advanced HIV.

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9
Q

What are 5 viral causes of encephalitis?

A

HSV

VZV

HIV

Arboviruses

Rabies

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10
Q

What is cerebritis?

A

Inflammation of the brain.

Bacterial infection associated with immunodeficiency or abscesses.

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11
Q

Abscesses (bacterial) are mostly caused by ?.

A

Streptococci

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12
Q

Name 3 parasites that can cause cycts in the CNS.

A

Toxoplasmosis

Cysticercosis

Echinococcosis

Rare unless immunocompromised.

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13
Q

Give 2 viral causes of myelitis.

A

Poliomyelitis

Rabies

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14
Q

What is the most common cause of meningitis?

A

Neisseria meningitidis.

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15
Q

What is the most common cause of meningitis in neonates?

A

Group B Streptococci.

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16
Q

When is meningococcal disease most common?

A

Winter months.

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17
Q

Meningococcal C vaccine has been used from ? onwards. Meningococcal B vaccine from ? onwards.

A

1999, 2013 - 2015

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18
Q

In what age group is incidence of meningococcal disease highest?

A

Infants (more specifically, 6 months)

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19
Q

Outline the pathology of meningococcal infection.

A

Begins with colonisation of the nasopharynx.

Some people are long term carriers (asymptomatic).

Mixing of populaitons leads to exposure, colonisation and invasion.

Invasion through the epithelium, into the blood and back into the meninges.

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20
Q

Basal skull fractures can expose the meninges, leading to ?

A

meningitis

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21
Q

The clinical features of meningitis overlap with?

A

Encephalitis

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22
Q

List some clinical features of meningitis and encephalitis.

A
  • Fever.
  • Heachache.
  • Stiff neck.
  • Photophobia.
  • Rash (purpuric - doesn’t blanche when you press it with a glass as it is due to necrosis not inflammation).
  • Reduced consiousness (GCS).
  • Confusion.
  • Seizures.
  • Focal CNS signs.
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23
Q

What is the relationship between meningitis and septicaemia?

A

In most cases, have both.

Can just have meningitis (no rash etc.) or just septicaemia (no headache etc.).

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24
Q

When diagnosing bacterial meningitis, any two of the following gives 95% sensitivity:

A

Headache, neck stiffness, fever, GCS < 14

25
Q

What are the clinical features of Meningococcal infection?

A

Children & young adults, possible outbreaks.

Acute, sepsis, purpuric rash, peripheral gangrene.

26
Q

What are the clinical features of Pneumococcal infection?

A

Older adults, immunocompromised, trauma, RTIs.

Less acute, no rash, high mortality & morbidity.

27
Q

What are the clinical features of Group B Streptococci infection?

A

Neonates acquire bacteria during birth.

Low mortality, but still risk of CN damage.

28
Q

What are the clinical features of Listeriosis?

A

Neonates, elderly, immunocompromised, pregnancy.

Meningoencephalitis, rhombencephalitis (inflammation of the hind brain), BCs +ve.

29
Q

What are the clinical features of tuberculosis?

A

Insidious onset of fever, confusion, coma.

High CSF protein.

30
Q

How much CSF fluid is required for culture?

A

Around 8 ml

31
Q

What are the clinical features of a brain abscess?

A

Associated with chronic URTIs (sinusitis, otitis media).

Insidious onset or may present with seizures.

32
Q

Give some investigations you’d carry out when investigating infections of the CNS.

A
  • Full blood count (FBC) & inflammatory markers (eg. CRP).
  • Renal function (U&Es) & coagulation tests (APTT & PT).
  • Blood cultures (x2) & blood for PCR tests.
  • Consider HIV test.
  • Consider CT scan if risk of raised ICP/ brain lesions.
  • Lumbar puncture - CSF.
33
Q

When carrying out a lumbar puncture, how many CSF samples are taken? What tests are carried out?

A

3.

Samples 1 and 3 get sent for microscopy and microbiology (RCC, WCC and differential, organisms, PCR tests).

Sample 2 sent for biochemistry (protein, glucose).

Additional tests required for M. tuberculosis and Cryptococcus.

34
Q

Is CT required before LP if there are no signs of raised ICP?

A

No.

35
Q

What colour should CSF be?

A

Clear and colourless.

36
Q

CSF results: Opening pressure > ? cm indicated raised ICP.

A

18

37
Q

What does a cloudy appearance of CSF indicate?

A

Bacterial meningitis (build up of WBCs and protein)

38
Q

If RBC are > 1 per mm3 in CSF, what can this indicate?

A

Traumatic lumbar puncture or sub-arachnoid haemorrhage.

Compare bottles 1 and 3.

39
Q

If WCC is > 5 per mm3 in CSF, what can this indicate?

A

Abnormal.

If mostly neutrophils = bacterial.

If mostly lymphocytes = TB, viral meningitis or abscess.

40
Q

If protein > 1 g/L, what does this indicate?

A

bacterial or TB meningitis

41
Q

If CSF glucose < 50 % of blood glucose, what does this suggest?

A

bacterial or TB meningitis

42
Q

If bacterial meningitis is suspected, what treatment is given?

A

Ceftriaxone or cefotaxime (or benzylpenicillin) for 1 week.

  • If severe penicillin allergy → vancomycin + **meropenem or rifampicin or cotrimoxazole.*
  • *

& dexamethasone (steroid) IV 0.15mg/kg QDS for 4 days.

43
Q

If listeroisis is suspected, what is the treatment?

A

Amoxicillin IV 2g QDS for 3 weeks.

44
Q

If viral encephalitis suspected, what is the treatment/

A

Aciclovir IV 10mg/kg TDS for 3 wks.

45
Q

If TB is suspected, what is the treatment?

A

Rifampicin, isoniazid, pyrazinamide, ethambutol

& dexamethasone IV 0.1mg/kg QDS for 1 week.

Converted to PO (steroids) and reduced to zero over 8 wks.

46
Q

Sepsis is likely to occur in bacterial meningitis so it is important to use the ? when treating.

A

Sepsis Six

47
Q

What is the prognosis for meningococcal meningitis?

A
  • Mortality ~10%.
  • Cranial nerve palsies (including deafness).
  • Post-infective immunological complications (arthritis, pericarditis).
48
Q

What is the prognosis for meningococcal septicaemia (without meningitis)?

A
  • Mortality ~40%.
  • Gangrene of purpura & peripheries.
  • Post-infective immunological complications (arthritis, pericarditis).
49
Q

What is the prognosis of pneumococcal meningitis?

A
  • Mortality ~25%.
  • Cranial nerve palsies (including deafness).
  • Relapses & metastatic infections.
50
Q

How is meningitis prevented? (2)

A

Chemoprophylaxis (vs. meningococcus) - for household and kissing contacts.

Immunoprophylaxis - vaccines against:

  • Meningococcus A, B, C, W135, Y.
  • Pneumococcus (7 serotypes).
  • Haemophilus influenzae type B (HiB).
  • Some causes of viral meningitis.
51
Q

Name a virus that can cause peripheral nerve infections.

A
  • HSV causes oral (HSV-1) and genital (HSV-2) herpes.
  • VZV causes chickenpox (varicella) and recurs as shingles (zoster).
52
Q

How can viruses cause peripheral nerve infections?

A

May infect trigeminal ganglia or dorsal root ganglia & become latent → recurrences may occur (eg. with physical or mental stress).

53
Q

What is Mycobacterium leprae?

A

Mycobacterial infection that causes leprosy.

54
Q

What is the pathology of Mycobacterium laprae infection?

A

Infects skin & nerves (& nasal mucosa & eye).

→ Subtle skin lesions & peripheral nerve lesions (neuropathy).

→ Nerve enlargement & loss of sensation (hypoaesthesia).

→ Progressive soft tissue damage & secondary infection.

55
Q

What is Ramsay-Hunt Syndrome?

A

Herpes Zoster of the Facial nerve.

Reactivation of VZV in geniculate ganglion –> facial nerve palsy (LMN), loss of taste (anterior 2/3), pain in ear and vesicles (some vestibular-cochlear symptoms and signs may also occur).

Affects CN VII and CVIII.

56
Q

What is meningitis?

A

Inflammation of the meninges.

57
Q

What is encephalitis?

A

Inflammation of the brain.

58
Q

For bacterial/viral/tuberculous CNS infections, describe:

WCC

Major WBC type

Protein

Glucose (vs serum)

A

B3 CTB (13 decks)

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