A boy aged 9 years and 8 months, with no past history of interest, was referred to the paediatric emergency department from his health centre for headache and proptosis. Onset of symptoms 4 days earlier, with fever, vomiting, headache and nasal congestion; diagnosed at his health centre with sinusitis and on antibiotic treatment with amoxicillin-clavulanic acid for 48 hours, with no improvement in symptoms. He reported severe right frontotemporal headache and right eyelid oedema that had evolved into proptosis in the last few hours.
Physical examination revealed slight proptosis of the right eye, with slight eyelid swelling, as well as obstruction of the nostril on the same side. The neurological examination revealed only a slight difficulty in conjugate gaze.
Given the poor clinical course of the sinusitis and the appearance of neurological symptoms, an emergency cranial CT scan was performed with the clinical suspicion of a possible intracranial complication. The CT scan showed pansinusitis, a subperiosteal phlegmon on the medial wall of the right orbit and a small right frontal subdural empyema (1.8 x 1.8 x 0.6 cm). 

After a joint assessment with professionals from the neurosurgery department, it was decided to maintain a wait-and-see attitude. Empirical intravenous treatment was started with cefotaxime, vancomycin and metronidazole. The primary focus (pansinusitis) was drained and the sinuses were evacuated via a nasal approach. All cultures were negative.
The clinical course was favourable, with disappearance of the symptoms a few days after the start of treatment. The patient underwent serial imaging tests (MRI), which showed a gradual decrease until complete disappearance eighteen days after treatment. Blood tests showed normalisation of the infectious parameters, with leukopenia and hypertransaminasemia secondary to the antibiotic treatment. 

Antibiotic treatment was discontinued twenty-six days after the start of treatment and the patient was discharged. Subsequently, he was monitored on an outpatient basis, with no evidence of neurological sequelae, and with absolute normalisation of the analytical parameters.