Subdural Empyema

CT and MRI Axial T2 and Diffusion study of brain show diffuse cerebral edema with mild ventriculomegaly. 

Right side mastoiditis.

A thin layer of subdural collection along tentorium and interhemispheric fissure with restricted diffusion is very typical of a Subdural Empyema.

Related post : Subdural-abscess

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.

Location: 

SDE more common in Supra tenotrium ( Cerebral convexity > interhemispheric fissure > tentorium) than Infratentorium (Cp angle > Cerebellar convexity) 

EDE in Supra tentorium common in Frontal region. 

Imaging findings:

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 sub dural hygroma and effusion. 

Clinical Presentation:

Can occur at any age, No gender predominence. 

Often present with headache and fever. May show signs of meningitis. 

Etiology: 

An mastoid or sinus infection present in more than 75%.

Can be a complication of trauma or neurosurgical procedure. 

Prognosis: 

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:

Mainly surgical drainage by wide craniotomy followed by patching. 

IV Antibiotics.