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MBBS 3: Internal Medicine > Meningitis and CSF Analysis > Flashcards

Meningitis and CSF Analysis Flashcards

1
Q

What is meningitis?

A
  • Meningitis is an inflammatory disease of the meninges, the tissues surrounding the brain and spinal cord
  • Meningitis is defined by an abnormal number of white blood cells in the cerebrospinal fluid
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2
Q

Common differential diagnosis of meningitis?

Most common subtypes

A
  1. bacterial meningitis
  2. viral meningitis
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3
Q

Uncommon differential diagnosis of meningitis?

A
  1. fungal meningitis
  2. TB meningitis
  3. parasitic meningitis
  4. CNS abscess
  5. drug induced meningitis e.g., NSAIDs, trimethoprim, sulfamethoxazole
  6. HIV
  7. neoplastic meningitis
  8. leptomeningeal carcinomatosis
  9. Lyme disease
  10. neurosarcoidosis
  11. neurosyphilis
  12. SLE
  13. vasculitis
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4
Q

Where is CSF formed?

A

choroid plexus - in pia mater

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5
Q

How much is the CSF in the body?

A

120 - 150 ml

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6
Q

In which direction does the CSF flow?

A

Unidirectional flow from ventricles to sub-arachnoidal space (cranium, myelum)

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7
Q

What is the normal CSF pressure?

A

6 - 20 cm H20

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8
Q

What causes CSF to increase?

A
  1. production vs. reabsorption imbalance
  2. cerebral edema
  3. mass lesions
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9
Q

Consequences of increased CSF pressure?

A

herniation of the:
1. cingulate gyrus
2. uncus of the temporal lobe, or
3. cerebellar tonsils

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10
Q

Clinical presentation of meningitis?

A
  1. Acute or Gradual presentation
  2. Fever
  3. General illness
  4. Head and neck ache
  5. Altered mental state
  6. Preceding illness: pneumonia, otitis
  7. Seizures
  8. Skin abnormalities
  9. Focal neurological manifestations e.g. photophobia
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11
Q

What are signs of meningeal irritation?

A
  1. Kernig sign
  2. Brudzinski sign
  3. Jolt accentuation of headache
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12
Q

Describe the maneuver of Kernigs signs?

A

place patient supine with hip flexed at 90 degrees and attempt to extend the leg at the knees

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13
Q

What is a positive Kernigs sign?

A

the test is positive when there is resistance to extension at the knee to >135 degrees or pain in the lower back or posterior thigh

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14
Q

Describe the Brudzinski sign maneuver?

A

place patient in the supine position and passively flex the head toward the chest

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15
Q

What is a positive Brudzinski sign?

A

the test is positive when there is flexion of the knees and hips of the patient

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16
Q

What is the jolt accentuation of headache maneuver?

A

patient rotates his/her head horizontally two to three times per second

17
Q

What is a positive jolt accentuation of headache test?

A

the test is positive if the patient reports exacerbation of his/her headache with his maneuver

18
Q

What is the skin manifestation in a patient with bacterial meningitis?

A

can start as a blanching rash and develops into a no-blanching red, purple or brownish petechial rash or purpura
- does not disappear when pressure is applied to the skin

19
Q

Contraindications of a lumbar puncture?

A
  1. Local infection
  2. Anatomical deformities
  3. Hemorrhagic diathesis (coagulopathy) or anticoagulant therapy
  4. Herniation risk e.g. increased ICP
  5. Platelets <20000
20
Q

What poses a herniation risk?

A
  1. clinical signs indicating herniation
    - hypertension, bradycardia, irregular respirations
  2. cranial mass lesion
    - suspected in the presence of focal neurological deficits
  3. increased intracranial pressure
21
Q

Principles of anti-sepsis in LP?

A
  1. Sterile equipment
  2. Sterile gloves
  3. Disinfection
    - Concentric circles away from the LP site
22
Q

Complications of LP?

A
  1. Herniation
  2. Local pain
  3. Headache
  4. Bleeding
  5. CSF leak
  6. Infection
  7. Epidermal cyst (sub-arachnoid)
23
Q

Describe the different appearances CSF can have?

A
  1. Normal: as water
  2. Cloudy - turbid: >200 WBCs or 400 RBCs /microL
  3. Bloody: 6000 RBCs /microL
24
Q

What is xanthochromia?

A

Breakdown of RBCs (Hb) in CSF
- first to oxyhemoglobin (pink), later to bilirubin (yellow)
e.g. subarachnoid bleeding - 90% sensitive after 12 hours duration up to 4 weeks

25
Q

Features of xanthochromia in CSF?

A
  1. Very high protein levels
  2. Systemic hyperbilirubinemia
26
Q

Normal CSF contents?

A
  1. Up to 5 WBC (3 PMN)
  2. 5 RBC /microL
    - avoid delays > reduces sensitivity
  3. Protein level 0.20 to 0.40 g/L
  4. CSF-to-serum glucose ratio = 0.6
27
Q

What does pleocytosis of WBCs mean in CSF?

A
  • Pleocytosis WBCs suggests infection
  • lymphocytosis suggests viral, TB, Cryptococcal
28
Q

What to do when you find WBC in bloody CSF?

A

deduct 1 WBC for every ~ 500 RBCs

29
Q

Increased protein in CSF could mean?

A

bacterial, TB and fungal meningitis

30
Q

Low glucose levels in CSF could mean?

A
  1. bacterial, TB, fungal meningitis
  2. malignancies
  3. hypoglycemia
31
Q

Cytology requires how much CSF for analysis?

A

10 - 15 ml

32
Q

Microbiological tests you can do on CSF?

A
  1. gram stain
  2. bacterial/fungal culture
  3. AFB
  4. MTB Xpert (ultra)
  5. mycobacterial culture
  6. CRAG
33
Q

Common causes of bacterial meningitis?

A
  1. Neisseria meningitidis
  2. streptococcus pneumoniae
  3. listeria monocytogenes
  4. coagulase-negative staphylococcus
  5. staphylococcus aureus
  6. gram-negative bacilli
  7. haemophilus influenzae
34
Q

Complications of otitis media?

A
  1. Meningitis
  2. Brain abscess
  3. Epi- and sub-dural empyema
  4. Lateral sinus thrombosis
35
Q

Microbiology of otitis media and meningitis?

A
  1. S pneumonia, H influenzae
  2. GN bacteria, especially in chronic OM
36
Q

Prevalence otogenic cause among meningitis cases?

A
  • <1% to 50% of meningitis cases
  • As common in adults as in children
  • Mainly acute OM, rarely chronic OM
37
Q

Role of surgery in otitis?

A

drainage middle ear, any intracranial sites, mastoid

38
Q

Which types of meningitis have the highest complication and mortality rates?

A

Bacterial, tuberculous and cryptococcal meningitis

MBBS 3: Internal Medicine (72 decks)

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