Nasal Encephalocoele

This patient in her 70s presents with nasal obstructive symptoms. Sagittal gadolinium-enhanced T1-weighted MR image shows a defect in the dura of the anterior cranial fossa. The frontal lobe herniates through the defect into the nasal cavity. It is important to recognise this entity as a cause of nasal obstruction, as a well-intentioned biopsy may lead to troublesome CSF leak or meningitis.