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Case 13 > CNS Infections > Flashcards

CNS Infections Flashcards

1
Q

What are the functions of the meninges?

A
  • Protect brain + spinal cord
  • Blood supply to skull
  • Space for flow of CSF
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2
Q

What are the routes of CNS infections?

A
  • Blood borne
  • Peripheral nerves (rabies)
  • Local invasion from ears, sinus
  • Local injury - face, skull, spine
  • Congenital defects
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3
Q

Where does blood borne invasion take place across?

A
  • BBB to cause encephalitis

- Blood-CSF barrier to cause meningitis

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4
Q

How do microbes travel across barrier of CNS to cause infection?

A
  • Growing across + infecting cells that make up barrier
  • Passively transported across intracellular vacuoles
  • Carried by infected WBCs
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5
Q

Which microbes invade CNS via peripheral nerves and how?

A
  • HSV, VSV, rabies
  • HSV and VSV travel from mucosal and skin lesions up axons to dorsal root ganglion
  • Rabies introduced into muscle via bite > peripheral nerves > glial cells + neurones
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6
Q

What is meningitis?

A
  • Inflammation + infection of meninges
  • Bacterial (serious)
  • Viral (more common, less severe)
  • Notifiable disease
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7
Q

What organisms cause bacterial meningitis?

A
  • Strep pneumoniae
  • Neisseria meningitidis
  • Listeria monocytogenes
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8
Q

What organisms cause viral meningitis?

A
  • Enterovirus
  • HSV
  • CMC
  • EBV
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9
Q

What organisms cause fungal meningitis?

A

Cryptococcus neoformans

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10
Q

What causes meningitis in newborns?

A
  • Group B Strep
  • Strep pneumoniae
  • Listeria
  • E.coli
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11
Q

What causes meningitis in babies + children?

A
  • Group B Strep
  • Strep pneumoniae
  • Neisseria
  • Hib
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12
Q

What causes meningitis in teens and young adults?

A
  • Strep pneumoniae

- Neisseria

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13
Q

What causes meningitis in older adults?

A
  • Group B Strep
  • Strep pneumoniae
  • Neisseria
  • Hib
  • Listeria
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14
Q

How are CNS infections spread?

A
  • Mothers can pass group B strep + E.coli during labour and birth
  • Hib + Strep spread by coughing/sneezing
  • N.meningitidis spread by sharing resp or throat secretions
  • E.coli + Listeria = by contaminated food
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15
Q

What are the signs and symptoms of meningitis in babies?

A
  • Fever, cold hands + feet
  • Rapid breathing, grunting
  • Unusual cry, moaning
  • Stiff neck, dislike bright lights
  • Refusing food, vomiting
  • Drowsy, floppy, unresponsive
  • Pale, blotchy skin spots/rash
  • Tense, bulging fontanelle
  • Convulsions/ seizures
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16
Q

What are the signs and symptoms of meningitis in adults?

A
  • Fever, cold hands + feet
  • Drowsy
  • Severe muscle pain + headache
  • Dislike bright lights, stiff neck
  • Vomiting
  • Confusion + irritability
  • Pale, blotchy skin spots/rash
  • Convulsions/ seizures
17
Q

When is a head CT considered?

A
  • Low GCS
  • New focal neurology
  • Other signs of increased ICP
  • Papilloedema
  • Immunocompromised
  • Perform LP ASAP if no contraindication
18
Q

What are the contraindications of LP?

A
  • Signs suggesting increased ICP
  • Shock
  • Extensive or spreading purpura (septic rash)
  • Convulsions
  • Cogagulation abnormalities
  • Superficial infection @ LP site
  • Resp insufficiency
19
Q

What CSF findings are found in bacterial meningitis?

A
  • Yellow
  • High polymorphs + protein
  • Low glucose
20
Q

What CSF findings are found in viral meningitis?

A
  • Clear

- High lymphocytes

21
Q

What CSF findings are found in TB

A
  • Yellowish/ viscous
  • High lymphocytes
  • Low glucose
22
Q

What CSF findings are found in viral meningitis?

A
  • Yellowish/ viscous

- High lymphocytes

23
Q

How is bacterial meningitis managed?

A
  • Cefotaxime/ Cefriaxone
    +/- Vancomycin
  • Newborns + elderly may require Ampicillin/ Amoxicillin
24
Q

What is viral meningitis characterised by?

A
  • Headache
  • Fever
  • Photophobia
  • Less neck stiffness
25
Q

What are the causative agents of viral meningitis?

A
  • HSV
  • Mumps
  • Enterovirus
  • HIV
26
Q

What is encephalitis and the clinical presentation?

A
  • Acute inflammation + swelling of brain
  • Caused by infection or immune response
  • Presents with headache, fever, change in cognitive state
  • Reduced GCS or seizures
27
Q

What are the causative agents of encephalitis?

A
  • HSV
  • VSV
  • CMV
  • Mumps
  • Poliovirus
  • Rabies
  • HIV
  • Fungi, parasitic or bacterial = rare
28
Q

How is encephalitis diagnosed?

A
  • CSF for viral PCR + microscopy, culture + sensitivities
  • Blood culture
  • CT head, MRI brain or ECG to confirm
  • Usually treat with Acyclovir
  • Treating early before development haemorrhagic necrosis = critical to improve neurological outcome
29
Q

What are the complications of encephalitis?

A
  • High mortality if untreated
  • Memory problems
  • Personality + behavioural changes
  • Speech + language problems
  • Problems swallowing
  • Seizures
  • Emotional + psychological problems
  • Problems with attention, concentrating, planning + problem solving
  • Problems with balance, co-ordination + movement
  • Persistent tiredness
30
Q

What is a cerebral abscess?

A
  • Infection in or around skull - sinuses, otitis media, dental abscess
  • Severe head injury
  • Infection elsewhere which spreads via blood
  • Symptoms associated with expanding intracranial mass +/- sepsis FFFF (fever, fits, focal, fatal)
31
Q

How is a cerebral abscess diagnosed?

A
  • Contrast enhanced CT (or MRI)
  • LP contraindicated
  • Locate source
  • Blood cultures
32
Q

How is cerebral abscess treated?

A
  • Antibiotics based on causative organism

- Surgical defridement/ removal of abscess and distal infected area

33
Q

What is the significance of danger triangle of face?

A
  • Skin here is thin
  • Facial veins = valveless + communicate directly with cavernous sinus
  • Infection of are can spread intra cranially + cause septic cavernous sinus thrombosis
34
Q

What can cause post-op CNS infections?

A

Mechanical shunts = regulate ICP

35
Q

What is rabies encephalitis?

A
  • Predominantly in Africa and Asia
  • Most cases in children under 15
    Infections spreads from bite > CNS
  • Striking symptoms of furious rabies - removing inhibition + initiating aggression
  • Virus shed in saliva
36
Q

What is the prevention and treatment of rabies?

A
  • Vaccine
  • Hits poor + rural
  • Following bite - rapid post bite wound washing with warm soapy water + rapid assessment has big impact
  • Location important
  • Post exposure vaccines
37
Q

Which CNS infections are seen in immunocompromised patients?

A
  • CMV encephalitis
  • Mycobacterium tuberculosis + Cryptococcus neoformans meningitis
  • Toxoplasmosis - parasitic
  • Kaposi sarcoma
  • Neurosyphilis

Case 13 (9 decks)

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