REPRINTED FROM THE 2023 HYPERBARIC INDICATIONS MANUAL 15 Edition:Intracranial Abscess.

The term "intracranial abscess" (ICA) includes cerebral abscess, subdural empyema, and epidural empyema, which share many diagnostic and therapeutic similarities and, frequently, very similar etiologies. Infection may occur and spread from a contiguous infection such as sinusitis, otitis, mastoiditis, or dental infection; hematogenous seeding; or cranial trauma. Brain abscess usually results from predisposing factors such as HIV infection, immunosuppressive drug treatment, surgery, adjacent infection (i.e., mastoiditis, sinusitis, dental infection), or systemic infection causing bacteremia. Approximately 30% to 50% of infections are caused by contiguous spread of local infections. Hematogenous spread is responsible in around a third of cases, with the mechanism for the remainder not identifiable.