what are the predisposing factors of brain abscess
- Direct spread through sinus or skull fracture or infection in the sinuses or middle ear etc.
- Haematogenous spread from any side of primary infection mostly chest, heart, bone or dental abscess. 
What is the most common group of bacteria that causes brain abscess
Streptococcus species
What Bacteria’s may cause brain abscess
- Streptococcus
- bacteriodes
- enterobacteria
- staphylococcus
What is a brain abscess
A collection of pus or infected material within the brain parenchyma. Usually through spread of infection from the body to the brain
What are the symptoms of brain abscess
- Headache, drowsiness and confusion
- fever
- focal neurological defects Such as hemiplegia
- raised ICP
- seizures
- CN 3 and CN 6 palsy 
What are the investigations carried out for brain abscess
- CT scan brain
- MRI brain
- examination of abscess fluid by Gram stain or culture
- blood CBC/ESR
What is a characteristic finding of brain abscess in CT scan brain
Single or multiple low density areas that are peripherally enhanced. Ring appearance with central low density and surrounding cerebral oedema
Why is lumbar puncture contraindicated in brain abscess
Raised ICP. May cause brain herniation. CSF finding is not helpful
What does blood CBC/ESR show in brain abscess
- Leucocytosis
- raised ESR
In HIV patients 90% of brain lesions are what
- Lymphoma
- toxoplasmosis
What is the best investigation for brain access
Brain CT scan
What is the treatment for patients with HIV suffering from cerebral toxoplasmolysis
- Pyrimethamine
- Sulfadiazine
What is the Treatment for brain abscess
- Medical
- surgical
What is the initial empirical antibiotic treatment for brain abscess
- Ceftriaxone 2 g IV 12 hourly
- Vancomycin 1 g 12 hourly
- metronidazole 15 mg /KG (loading dose) followed by 7.5 mg /KG IV six hourly
What is the specific treatment for brain abscess medical
Depends on the species being treated
1. Penicillin for streptococci
2. metronidazole for anaerobes
3. ceftazidime for gram-negative bacilli
What is the surgical management of brain abscess
Stereotactic aspiration or surgical excision
Patient with increased intracranial pressure may benefit by providing what other type of medication
Steroids such as dexamethasone 10 mg IV once, then 4 mg IV six hourly for three or four days. 
