Meningitis (N) Flashcards

1
Q

Define meningitis.

A

Infection of the meninges in the brain or spinal cord, that is most commonly bacterial or viral in origin, but may also be fungal, parasitic or due to non-infectious causes

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2
Q

Describe the aetiology of meningitis.

A

Inflammation of pia and arachnoid mater due to infection –> immune response causes cerebral oedema and increased intracranial pressure leading to:

  1. herniation
  2. raised ICP and systemic hypotension, reducing cerebral perfusion
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3
Q

What demographics does meningitis tend to happen in most commonly? (2)

A
  • children <1y
  • median age in adults = 43
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4
Q

Which bacteria causes meningitis in neonates?

A

Group B Streptococci

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5
Q

Which bacteria cause meningitis in children and adults? (3)

A
  • Neisseria meningitidis - gram -ve diplococci (also causes petechial non-blanching rash)
  • Streptococcus pneumoniae - gram +ve diplococci
  • Haemophilus influenzae
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6
Q

Which bacteria cause meningitis in the elderly?

A

Streptococcus pneumoniae (and Listeria monocyogenes)

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7
Q

What are the viral causes of meningitis? (5)

A
  • enteroviruses - most common cause (poliovirus, Coxsackie A&B)
  • HSV
  • VZV
  • mumps
  • HIV
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8
Q

What is a fungal cause of meningitis?

A

Cryptococcus (common in HIV patients)

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9
Q

What are some other forms of meningitis? (2)

A
  • aseptic meningitis
  • Mollaret’s meningitis
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10
Q

What is the predominant causative organism of meningitis?

A

Neisseria meningitidis

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11
Q

What is the similarity/difference between bacterial and viral meningitis?

A

Features are similar, although viral meningitis is less acute and usually self-limiting

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12
Q

What are the clinical features of meningitis? (10)

A
  • fever
  • headache (early)
  • neck stiffness (late)
  • photophobia
  • irritability
  • nausea and vomiting
  • altered mental status
  • seizures (more in encephalitis)
  • deafness
  • non-blanching petechial rash (late, more likely due to N. meningitidis)
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13
Q

What might you see on examination of meningitis? (2)

A
  • Kernig sign - inability to straighten leg when hip is flexed to 90 degrees
  • Brudzinski sign - forced flexion of neck elicits a reflex flexion of hips
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14
Q

What are the signs of meningism? (4)

A
  • stiff neck
  • photophobia
  • Kernig’s sign
  • Brudzinski’s sign
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15
Q

What signs of infection might you see in meningitis? (5)

A
  • fever
  • tachycardia
  • hypotension
  • skin rash
  • altered mental state
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16
Q

What is a sign you would see in meningococcal sepsis?

A

Non-blanching rash

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17
Q

What are the clinical features of meningitis in neonates? (7)

A
  • no classic triad of fever, headache, neck stiffness
  • lethargy
  • irritability
  • poor appetite
  • vomiting
  • fontanelle bulging
  • seizures
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18
Q

What is the classic triad of meningitis?

A

Fever + headache + neck stiffness

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19
Q

How does fungal meningitis present?

A

Onset of headache and fever over weeks/months

20
Q

What are the risk factors for meningitis? (7)

A
  • immunocompromised
  • crowded living conditions
  • otitis media, inner ear infections, mastoiditis
  • sinusitis
  • CSF leak after head trauma/neurosurgery
  • sepsis
  • alcoholism
21
Q

What are the 1st-line investigations for meningitis? (5)

A
  • lumbar puncture
  • blood culture
  • serum pneumococcal and meningococcal PCR
  • blood glucose
  • FBC and differential
22
Q

What is the main investigation needed for meningitis?

A

Lumbar puncture for CSF analysis (only if no signs of raised ICP)

23
Q

When is lumbar puncture done for suspected meningitis?

A

Usually done after CT - but if GCS15, no symptoms of raised ICP and focal neurology –> can be done without CT to save time

24
Q

What would bacterial-meningitis CSF show? (4)

A
  • cloudy
  • very high neutrophils (polymorphonuclear cells)
  • very high protein
  • very low glucose (typically <50% serum glucose)
25
Q

What would viral-meningitis CSF show? (5)

A
  • clear
  • high lymphocytes
  • high protein
  • normal glucose
  • normal opening pressure
26
Q

What would TB-infected CSF show? (5)

A
  • clear/cloudy/fibrin web
  • high lymphocytes
  • high protein
  • low glucose
  • high opening pressure
27
Q

What are normal and elevated opening pressures of CSF in meningitis?

A
  • 7-18cm CSF if normal
  • may be >40 in meningitis
28
Q

What are some contraindications for lumbar puncture in meningitis? (7)

A
  • raised ICP
  • suspected intracranial mass lesion
  • focal neurological signs
  • papilloedema
  • trauma
  • middle ear pathology
  • major coagulopathy
29
Q

What scan do we do in suspected meningitis and when?

A

CT head before lumbar puncture if increased ICP suspected, to assess risk of brain herniation due to lumbar puncture

30
Q

What investigations needs to be done in meningitis before starting Abx?

A

Two sets of blood cultures

31
Q

What are some differential diagnoses for meningitis? (2)

A
  • encephalitis - abnormal cerebral function (altered behaviour, speech, motor disorders especially with fever, seizures)
  • drug-induced meningitis (Hx culprit drug use: NSAIDs, trimethoprim/sulfamethoxazole, amoxicillin, ranitidine - CSF shows neutrophilic pleocytosis)
32
Q

What is the management flowchart for meningitis (no septicaemia)?

A
  • meningitic signs predominate i.e. neck stiffness, photophobia
  • dexamethasone 4-10mg/6h IV
  • if signs of ICP –> ICU and do NOT do LP
  • if no shock or ICP –> do LP
  • 2g cefotaxime IV post-LP
  • careful monitoring
33
Q

What is the management flowchart for septicaemic meningitis?

A
  • septicaemic signs predominate e.g. poor cap refill, cold hands and feet, rash
  • do not attempt LP
  • cefotaxime 2g IV
  • signs of shock?
    • Y = ICU for fluid resus, intubation, inotropes, vasopressors
    • N = careful monitoring
34
Q

In primary care, what should be done immediately when bacterial meningitis suspected?

A

IV/IM benzylpenicillin then send to hospital

35
Q

In hospital, when should lumbar puncture be delayed in meningitis? (4)

A
  • sepsis/rapidly evolving rash signs
  • severe respiratory/cardiac compromise
  • significant bleeding risk
  • signs of ICP e.g. papilloedema, neurological signs, seizures, GCS<12
36
Q

What do we do if raised ICP in meningitis? (5)

A
  • secure airway + high-flow oxygen
  • bloods and blood cultures from IV access
  • IV dexamethasone
  • IV Abx - cefotaxime (+/- ampicillin)
  • CT
37
Q

What do we do if normal ICP in meningitis? (4)

A
  • take bloods and blood cultures
  • do lumbar puncture
  • IV Abx
  • IV dexamethasone (AVOID in meningococcal septicaemia)
  • (CT not normally done)
38
Q

What are the immediate Abx given for meningitis? (3)

A
  • first-line: 3rd generation cephalosporin - cefotaxime or ceftriaxone
  • if >55 / immunocompromised: add ampicillin (or amoxicillin/rifampicin)
  • (Abx given before LP if high ICP, after LP if normal)
  • if in GP: IM/IV benzylpenicillin (ceftriaxone if allergic)
39
Q

What do we give alongside Abx in meningitis?

A

IV dexamethasone - shortly before/after first dose of Abx, associated with reduced risk of complications

Avoid if meningococcal septicaemia

40
Q

In meningitis, do you give Abx before or after lumbar puncture?

A

Empirical Abx before LP (cefotaxime/ceftriaxone), targeted Abx after

41
Q

What targeted Abx can we give for meningitis? (3)

A
  • Listeria monocytogenes - amoxicillin
  • S. aureus - flucloxacillin (vancomycin if penicillin allergic/MRSA)
  • Mycobacterium tuberculosis - isoniazid/pyridoxine
  • (rest are cefotaxime/ceftriaxone)
42
Q

How would we manage viral meningitis? (3)

A
  • supportive measures
  • usually self-limiting
  • maybe antivirals
43
Q

What do we give to close contacts of those with meningitis?

A

Prophylactic Abx - oral ciprofloxacin or rifampicin

44
Q

What are some complications of meningitis? (9)

A
  • deafness (sensorineural hearing loss - most common complication)
  • septicaemia
  • shock
  • DIC
  • cerebral oedema
  • renal failure
  • cranial nerve lesion
  • seizures
  • hydrocephalus
45
Q

Describe the prognosis of (bacterial vs viral) meningitis.

A
  • bacterial meningitis - fatal if untreated
  • viral meningitis - resolves spontaneously in majority of cases