Critical basilar expansion of the sphenoidal sinus associated with a spontaneous cerebrospinal fluid fistula: the relevance of multidetector computed tomographic cisternography Expansão basilar crítica do seio esfenoidal associada à fístula liquórica espontânea: a relevância da cisternotomografia computadorizada multidetectores

A 46-year-old woman presented with an intermittent nontraumatic cerebrospinal fluid (CSF) left rhinorrhea. A multidetector computed tomographic (MDCT) study was performed to investigate a CSF fistula (Figure). The sphenoidal sinus is prone to CSF leakage, when anatomical variations occur. The basilar expansion is a posterior expansion of the sphenoidal sinus (postsellar). It is considered critical for endoscopic surgery approach and also a predisposing factor to spontaneous or posttraumatic CSF fistula when the posterior wall of the sphenoidal sinus is ≤2 mm thick1. Similar imaging reports in current literature are rare1-4. Typical pattern on MDCT images, particularly after iodinated intrathecal contrast administration, reinforces its relevance to confirm the exact location of the CSF fistula for a proper surgical approach.