CNS Infections

Question 1

Why are CNS infections so important to diagnose quickly?

Answer 1

Untreated can cause brain herniation and death or permanent paralysis, as brain and spinal cord do not regenerate

Question 2

Describe pyogenic meningitis morphologically

Answer 2

Thick layer of suppurative exudate covering the leptomeninges over the surface of the brain

Question 3

Describe pyogenic meningitis microscopically

Answer 3

Neutrophils in the subarachnoid space

Question 4

Which types of viruses cause viral meningitis?

Answer 4

Enteroviruses

Question 5

How is viral meningitis diagnosed?

Answer 5

Viral stool culture

Throat swab

CSF PCR

Question 6

Examples of viruses that cause viral encephalitis and treatment

Answer 6

Herpes simplex- Rapid high dose aciclovir
Varicella zoster- high dose aciclovir
CMV, HIV, Measles, West Nile, Rabies

Question 7

Clinical features of encephalitis

Answer 7

Meningismus
Stupor/coma
Seizures, paralysis
Confusion, psychosis
Speech and memory symptoms

Question 8

Examples of meningitis complications

Answer 8

Limb loss
Deafness
Blindness
Cerebral palsy
Quadriplegia
Mental impairment

Question 9

Pathogenesis of bacterial meningitis

Answer 9

1) Nasopharyngeal colonisation
2) Direct extension of bacteria eg from sinusitis, Mastoiditis or brain abcess across skull defect or fracture
3) From remote foci of infection eg endocarditis, pneumonia, UTI

Question 10

What bacteria causes meningococcal meningitis, how does it gain access to the meninges, and what causes the symptoms it causes?

Answer 10

Neisseria meningitis

Accesses meninges through blood stream

Symptoms due to endotoxin

Question 11

Which patients are most susceptible to Strep pneumoniae meningitis

Answer 11

Hospital, CSF skull fractures, diabetics and alocholics, young children

Question 12

Which patients are most susceptible to listeria monocytogenes and what is the treatment of choice

Answer 12

Neonates, >55 years, Immuno suppressed

IV ampicillin/amoxicillin

Question 13

Which patients are most susceptible to cryptococcal meningitis (also what kind of infection is it+treatment)

Answer 13

HIV patients

Fungal infection

IV amphotericin B/Flucytosine + Fluconazole

Question 14

Clinical signs of bacterial meningitis

Answer 14

Fever

Neck stiffness

Altered conciousness

Question 15

How can meningitis be diagnosed from a microbiology POV

Answer 15

Blood culture
Throat swab
Blood EDTA for PCR
CSF fluid (Lumbar Puncture)

Question 16

What is aseptic meningitis?

Answer 16

A term used to mean non pyogenic meningitis

CSF has low WBC, normal glucose, slightly elevated protein

Question 17

When is a CT scan indicated?

Answer 17

When patients have papilloedema or focal neurological signs

ABx should not be delayed for investigations

Question 18

Empiric ABx therapy

Answer 18

IV Ceftriaxone 2g bd
+ IV ampicillin/ amoxicillin 2g qds if listeria suspected

Penicillin allergy
Chloramphenicol with vancomycin

Co-trimoxazole has been used succesfully on own.

Question 19

What role do steroids play?

Answer 19

All patients with suspected bac meningitis should get before or with first dose of ABx, reduces mortality

Don’t give in immunocmpromised