Interhemispheric subdural empyemas are uncommon in healthy young people. Since they may occur with nonspecific signs and symptoms in the early period, they should be considered in the differential diagnosis of other nervous system infections, subdural hematoma, and subarachnoid haemorrhage. Generally, they develop secondary to paranasal sinus infections. Clinical profile, which varies depending on the localization, is named as “falx syndrome”. Typical appearance of such lesions on cerebral angiography is called an ‘S-shaped deformity’. They show similar clinical and radiological characteristics with the interhemispheric subdural hematomas. The treatment is surgical drainage and high-dose antibiotherapy for 4-6 weeks.

Our patient was a case of interhemispheric subdural empyema which developed after frontal sinusitis. While clinical manifestation was ‘falx syndrome’, angiography revealed an “S-shaped” deformity.

Keywords: Cerebral angiography, falx syndrome, interhemispheric subdural empyema