To report a case of simultaneous orbital cellulitis and intracranial complications of acute sinusitis in a young patient.

The 11-year-old male presented with a one-day history of left periorbital erythematous swelling, fever and headache. He was diagnosed with acute sinusitis at the department of otorhinolaryngology, and endoscopic sinus drainage of pus was performed. However, the patient's symptoms did not improve. The next day, a subdural abscess was found on brain computed tomography. He was treated by external drainage of the periosteal abscess via a subbrow incision and systemic antibiotics, as well as anticonvulsant medication.

Twenty days after external drainage and beginning systemic antibiotics and anticonvulsant treatment, he was discharged with improved orbital cellulitis symptoms and a resolved subdural abscess.