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Cerebrospinal fluid rhinorrhea: the significance of an air-fluid level in the sphenoid sinus.

The radiographs of 13 patients with proved cerebrospinal fluid (CSF) fistulas were reviewed, with special attention paid to the presence or absence of an air-fluid level in the sphenoid sinus. The findings on plain radiographs and tomograms were compared to carefully documented sources of CSF leak. Seven patients demonstrated air-fluid levels in the sphenoid sinus even though the leak was through more anteriorly placed dural defects. The anatomical arrangement of the ostium of the sphenoid sinus is such that fluid will enter the sinus from the superior nasal recess, thus rendering air-fluid levels in the sphenoid sinus is such that fluid will enter the sinus from the superior nasal recess, thus rendering air-fluid levels in the sphenoid sinus a nonlocalizing finding in CSF fistulas.