Epidural abscess is the accumulation of pus between the cranial bone plate and the dura mater. It is the most common otogenic intracranial complication, accounting for approximately 1/3 of cases. Temporal lobe epidural abscesses are located between the tegmen tympani, tegmen mastoideum, and dura mater.
Pathology
In epidural abscesses, the local dura mater becomes congested, swollen, and thickened due to infection, with fibrin exudation and infiltration of inflammatory cells. The inflammatory exudate accumulates between the dura mater and the cranial bone plate, forming an abscess. The abscess may become localized due to surrounding granulation tissue.
If the body's resistance is strong and there is no acute inflammatory episode, the abscess may remain latent for a long time without obvious symptoms. However, if the abscess spreads, it can lead to subdural abscess, meningitis, or brain abscess.
Clinical manifestations
The symptoms and signs depend on the size and progression of the abscess.
Small abscesses are often asymptomatic or without specific clinical signs. In case of large or rapidly progressing abscesses, patients may experience ipsilateral headaches, typically localized, severe, throbbing pain. Body temperature is usually below 38°C.
If the abscess is large and extensive, it may stimulate the local meninges, causing increased intracranial pressure or compressing the adjacent brain parenchyma. This can result in generalized headaches, more pronounced on the affected side, and signs of meningeal irritation or focal neurological deficits. If the abscess is located at the petrous apex, petrous apex syndrome may occur and is characterized by involvement of the trigeminal nerve and abducens nerve, along with mild facial paralysis.
Treatment
Once the diagnosis is confirmed, immediate surgical exploration is required. The treatment includes:
- Removal of the middle ear lesion
- Exploration of the area of bony destruction
- Drainage of the abscess and removal of inflammatory granulation tissue