Subdural empyema (SDE, by its sigles in English) is a rare disease, but nevertheless it can cause a significant number of intracranial infections .
Subdural Empyemas represent approximately 20-33% of all intracranial infections.
The clinical presentation depends to a certain extent on the etiology. When the Empiemas result from sinusitis or mastoiditis that are often associated with seizures, focal neurological deficits and a rapid deterioration in the conscious state, progressing from obtundation to coma. Empies that occur secondary to previous trauma or surgery are usually more clinical indole.
In the most common scenario, patients develop subdural empyemas as a result of frontal sinusitis.
There are two putative propagation mechanisms:
- Direct extension
- Indirect: secondary to thrombophlebitis. Direct diffusion, as a result of erosion of the posterior wall of the frontal sinus (the corollary of a swollen Pott tumor) is relatively uncommon. It is believed that vein thrombophlebitis is the most common cause of spread.
- Frontal sinusitis: great majority
- Mastoiditis / otitis media
- Surgical intervention
- Existing subdural hematoma
Complications are relatively common and may be the cause of the infection. They include:
- Cortical venous thrombosis with or without venous infarction
- Cerebritis or brain abscess formation
- Radiographic characteristics
The Subdural Empiemas usually look like subdural hematomas in their form and the relationship with sutures and dural reflections. They are usually crescent shaped (compared to epidural empyemas that are typically lenticular). A membrane that surrounds intensely and uniformly after giving contrast is normally identified.
Magnetic Resonance Imaging
The appearance in the MRI is similar to the Computed Tomography although there is a greater capacity to detect the improvement of the contrast. On the other hand the content of the collection may show restricted diffusion.
MRI is also more sensitive to complications of subdural empyemas, for example, encephalitis, brain abscess, venous thrombosis.
Treatment and prognosis
The mortality associated with subdural empyemas now approaches 10%, compared to approximately 15 to 40% in the pre-CT era (Computed Tomography).
The success of the treatment is based on a rapid diagnosis, followed by the surgical evacuation of the collection and administration of the appropriate antibiotics.