Head CT > Infection > Extra-axial CNS Infection

Extra-axial CNS Infection

Extra-axial CNS infections can involve epidural abscess or subdural empyema. Extra-axial CNS infections account for 20-30% of CNS infections. Fifty percent of extra-axial infections are associated with sinusitis, usually frontal sinusitis. The infection occurs by direct extension or septic thrombophlebitis. Thirty percent of extra-axial infections occur post-craniotomy. Finally, 10-15% of extra-axial CNS infections are related to meningitis. CT findings include a focal fluid collection usually with an enhancing margin in a subdural or epidural location.