miscellaneous

Question 1

What is neurosyphilis?

Answer 1

Central nervous system invasion occurs early in infection in 30-40% of patients

Asymptomatic neurosyphilis can occur at any stage of syphilis

Question 2

Types of neurosyphilis, clinical presentation and how is it diagnosed?

Answer 2

Acute meningitis
Meningovascular (stuttering stroke)
Late symptomatic forms (> 2 years)

General paresis
Tabes dorsalis

Diagnosis by blood & CSF serology

Question 3

What is a brain abscess?

Answer 3

focal suppurative process within the brain parenchyma (pus in the substance of the brain)

Question 4

What are the methods of spread of a brain abscess?

Answer 4

Direct spread from “contiguous” suppurative focus (e.g. from ear, sinuses, teeth)

Haematogenous spread from a distant focus e.g. endocarditis, bronchiectasis (often multiple abscesses)

Trauma (e.g., open cranial fracture, post-neurosurgery)

Cryptogenic (no focus is recognised ~15-20 per cent of cases).

Question 5

Brain abscess microbiology: what are the causative agents?

Answer 5

Often mixed (polymicrobial)

Streptococci (60-70 %) e.g. Streptococcus “milleri”

Staphylococcus aureus (10-15 percent) most common pathogen in abscesses after trauma/surgery

Anaerobes e.g. Bacteroides spp.

Gram negative enteric bacteria (e.g. E.coli)
Others e.g. fungi, Mycobacterium tuberculosis, Toxoplasma gondii

Question 6

How do brain abscesses present clinically?

Answer 6

Headache (most)
Focal neurological deficit (30-50%)
Fever (<50%)
Nausea, vomiting
Seizures
Neck stiffness
(papilloedema)

Question 7

Management of brain abscesses

Answer 7

Drainage to reduce intercranial pressure

This confirms diagnosis by allowing access to pus for microbiological investigation and enhance efficacy of antibiotics

Question 8

What must be considered in the process of choosing antibiotics for CNS infections?

Answer 8

The difference between physiology of blood brain barrier and blood CSF barrier

Question 9

Which drugs can reach therapeutic concentrations when the blood brain barrier has broken down?

Answer 9

Ampicillin, 
Penicillin,
 Cefotaxime, 
Ceftazidime, 
and Metronidazole

Question 10

What steroids are used in the treatment of CNS infections?

Answer 10

Dexamethasone

10mg IV 15 minutes prior to antibiotics

Shown to decrease morbidity & mortality in S. pneumoniae but NOT N. meningitidis