Brain infection

Incidence-

• Higher in developing countries
• 8% of all intracranial space occupying lesions (SOL).
• About one sixth as frequent as bacterial meningitis
• 0.7% of all neurosurgical operations

Source of infection-

Contiguous suppurative focus

• Direct extension through osteitis /osteomyelitis/ meningitis
• Retrograde thrombophlebitic spread via diploic /emissary veins
• Local lymphatics

Post trauma (3-17.2%)

Hematogenous spread from a distant focus

Cryptogenic origin

Miscellaneous

Stages of abscess formation:

1 Early Cerebritis:

Perivascular inflammation, characterised by Neurutrophils infiltration and some swelling around infection site.

From Days 1-3

2. Late cerebritis:

A central area of necrosis develops as the surrounding oedema progresses. There is accumulation of fibroblasts around it

From Day 4-9

3. Early Capsule:

Establishment of a ring-enhancing capsule of Well-vascularised tissue with further fibroblast migration

Day 10-14

4. Late Capsule:

Collagen fibres and granulation tissue deposits leading to thickening of capsule effectively walling off the areas from surrounding brain.

Day 15 and beyond

Medical treatment-

• Antibiotics- Chloramphenicol, Metronidazole, Sulphonamides, Isoniazid, and Rifampin which penetrate well into normal brain and CSF.
• Staphylococcal brain abscess has shown that the penetration of Vancomycin is excellent; concentration of Vancomycin in the abscess fluid was found to be 80% of the simultaneously obtained serum concentration.
• Pre-operative use of antibiotics would prevent the spread of infection during aspiration or surgical removal of the abscess.
• Selection of antibiotics pre-operatively will be based on the etiology of an abscess and organisms most frequently encountered.
• Later on, after obtaining the culture and sensitivity, proper antibiotics should be started.
• The antibiotics most commonly used are cefotaxime, vancomycin and metronidazole.(effectiveness was 88%)

Brain abscess from right ear infection-

12 years / M

Known patient of right ear pus discharge

Headache, fits and fever

MRI Brain showed Right Temporal abscess with right side mastoiditis. (Fig 1 and 2)