Intracranial abscess

**Definition:** A condition of the cranial cavity, caused by an infection with a bacterial, viral, or fungal source. This condition is characterised by a focal accumulation of purulent material within the cranial cavity. This condition may present with fever, headache, and focal neurological deficits.

**Long definition:** A focal suppurative infection within the cranial cavity, including the epidural and subdural spaces, or in the brain, brainstem or cerebellum. The abscess is typically surrounded by a vascularised capsule. Cerebritis describes a nonencapsulated brain abscess. The infective agent may be bacterial, fungal, or parasitic. The signs and symptoms are variable but typically present as an expanding mass lesion, over a variable period of time, with headache, fever, and a focal neurologic deficit. Seizures may occur. Diagnosis is made by neuroimaging. Microbiologic diagnosis is made by gram stain and culture of abscess material.