<unk>  is a life-threatening infection, consisting of a localized collection of purulent material, usually unilateral, between the dura mater and the arachnoid mater.<unk>  may be classified according to location of the infection into 2 groups: intracranial and spinal, with intracranial being the more common of the two groups, accounting for 95% of<unk>  patients.<unk>  accounts for approximately 15-25% of focal central nervous system infections. In 2014, the incidence of<unk>  was estimated to be less than 1 case case per 100,000 individuals, with a male predominance. 
The most common pathogens in intracranial<unk>  are anaerobic and microaerophilic Streptococci, compared to spinal<unk>  epmyema, which can be caused by either Streptococci or Staphylococcus aureus. If left untreated,<unk>  frequently evolves into severe fever, headache, nausea, vomiting, seizures, coma, and subsequent mortality. Complications to<unk>  include status epilepticus, neurological deficits, and thrombosis. Prognosis is generally good with antimicrobial therapy. Physical examination of patients with<unk>  is usually remarkable for fever, facial pain, and altered mental status. MRI is the primary imaging study of epidural abscess, with CT scan as a secondary alternative. Treatment of<unk>  requires a combined medical and surgical approach. In order to evacuate the pus, burr hole placement or craniotomy may be used to treat the<unk> . The preferred surgical mainstay of treatment for<unk>  is craniotomy.
Subdural empyema
Epidural hematoma
Brain abscess
Epidural abscess
Subdural hematoma
Arachnoiditis
Brain herniation
Intraparenchymal hemorrhage