Friday 13 January 2012

Subdural Empyema - Abscess

35 y o male with severe left temporal headache.
On Admission CT study of brain shows:
A focal low density collection with peripheral enhancement along tentorium near left mastoid.
No odema in adjacent brain parenchyma obvious on CT.
No significant mass effect.
Left side mastoid poorly pneumatised and sclerotic. E/o left side mastoidectomy.

The collection show restricted diffusion on Diffusion weighted images with focal vasogenic odema in adjacent left temporal lobe white matter on FLAIR.

Imagingwise diagnosis given was Subdural Empyema - Abscess. 

Left temporal craniotomy with dural patching and grafting done.
Histopatholgy report : ‘Empyema - Pyogenic Abscess’; Microscopy shows few fragmented bits of largely necrosed brain parenchyma with evidence of central coagulative - ischaemic necrosis; partially flanked by inflammatory granulation tissue with dense mixed acute on chronic inflammatory infiltrate. Congested thrombosed blood vessels. No granulomas nor fungi seen. Towards the periphery are seen fragments of reactive glial tissue with reactive astrocytic proliferation. There is no evidence of tuberculosis or malignancy.

Related post : Subdural-empyema

Syn: Subdural (SDE) or Epidural (EDE) Abscess. 
An extra axial localised collection of pus in sudural or epidural space or both.
SDE is more common than EDE.
SDE more common in Supra tenotrium ( Cerebral convexity > interhemispheric fissure > tentorium) than Infratentorium (Cp angle > Cerebellar convexity) 
EDE Supra tentorium (Frontal region). 
Collection is extra axial cresentic shaped if SD and bi convex shaped if ED.
Density on CT and signal intensity on MR vary depending up on its density and protein content. 
Strong peripheral enhancement on post contrast is must. Restricted diffusion on MRI Diffusion is typical and is helpful to rule out other DDs like hygroma and effusion. 
Clinical issues:
Can occur at any age, No gender predominence. 
Often present with headache and fever. May show signs of meningitis. 
An associated mastoid or sinus infection present in more than 75%.
Can be a complication of trauma or neurosurgical procedure. 
Progress rapidly, fulminant course, a neurosurgical emergency.
Complications and bad prognosis more common in SDE than EDE are CVT, focal cerebritis, Parenchymal abscess, meningitis, Hydrocephalus. Reason is in EDE the tough dura limits the collection and act as barrier between infection and brain. 
Mortality is 10-15%. 
Diagnosis solely based on imaging.
Lumbar puncture can be fatal. Csf examination can be normal. 
Treatment is mainly surgical drainage by wide craniotomy followed by patching. IV Antibiotics. 

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