Brain accesses and other infections

Question 1

What is a brain abcess?

Answer 1

Focal supportive process within brain parenchyma (i.e. pus in substance of the brain)

Question 2

What are the main cause of brain accesses?

Answer 2

Usually mixed bacterial (polymicrobria)

Streptococci e.g. streptococcus anginosus (pus forming)

Staphylococcus
aureus

Gram negative enteric bacteria e.g. E coli, pseudomonas

Anaerobes

Other e.g. fungi, TB

Question 3

What are the mechanisms by which brain accesses can come about?

Answer 3

Direct spread from “continuous” suppurative focus e.g. ear***, sinus, teeth

Haematogenous spread from distant sources e.g. endocarditis, brochioectasis

Trauma e.g. skull fracture

Cryptogenic (no focus e.g. TB)

Question 4

What are the clinical presentations of brain accesses?

Answer 4

• Headache**
• Focal Neurological defects (30-50%)
• confusion/reduced GCS
• Fever (less than 50%)
  Nausea, vomiting)
• Dizziness/seizures
• Neck stiffness
• Papilloedema/Coma

Question 5

How do you manage brain accesses?

Answer 5

Brain drainage - reduce IC pressure, enhance diagnosis and treatment i.e. focus antibiotics

Question 6

Give some examples of antibiotics that will penetrate intracranial pus?

Answer 6

• Beta lactams e.g. benzyl Penecillin
  Ampicillin
• Cephasporins e.g Cefuroxime, cefotaxime and ceftazidime (3rd gen good against pseudomonas - otitis media)

Question 7

What are sinugenic and odontogenic accesses?

Answer 7

Come from SINUSES and TEETH

Question 8

What are orogenic accesses?

Answer 8

Comes from EAR

Question 9

What are the complications of brain accesses?

Answer 9

• Coning
• Increased IC pressure
• Mass effect
• Rupture, causing ventriculitis

Question 10

What is a subdural empyema?

Answer 10

Infection between dura and arachnoid mater

Question 11

What is the pathogenesis of subdural empyema?

Answer 11

Spread of infection from SINUSES (Usually), middle ear, mastoid or distant site (haematogenous)

Also following surgery e.g. staph aureus

Question 12

What are the causes of subdural empyema?

Answer 12

Polymicrobrial - depends on pathogenesis and location

Question 13

What is the clinical presentation of subdural empyema?

Answer 13

Headache
Fever
Focal neurological Defects *
Confusion/reduced GCS
Seizure 
Coma

Question 14

What is the management of subdural empyema?

Answer 14

Urgent surgical drainage of pus, antimicrobial agents

Question 15

What are ventriculoperitoneal (VP) shunts and External ventricular drains (EVD)?

Answer 15

Devices that monitor IC pressure and drain excess CSF

Question 16

What is the relevance for EVD and VP shunts?

Answer 16

Can become infected causing ventriculitis

Question 17

What are the causative organisms the cause infections associated with plastic devices?

Answer 17

Coagulase negative staph

skin flora