Doughnut Sign Research Articles

The "doughnut sign" in subdural effusion.

A 7-month-old infant developedHaemophilus influenzaemeningitis that failed to respond to appropriate therapy. Anterior fontanel subdural taps were negative. A subsequent sodium pertechnetate Tc 99m brain scan demonstrated a subdural fluid collection on the left, manifested as a doughnut sign. Following surgical evacuation of the effusion, the child recovered uneventfully.