Delayed postoperative CSF rhinorrhea of intrasellar arachnoid cyst

CSF rhinorrhea due to a transsphenoidal approach usually follows accidental or intentional arachnoid opening. We report a patient with an intrasellar arachnoid cyst, who developed delayed onset of CSF rhinorrhea. A sixty-two- year-old man presented with bitemporal type visual field defect for the las t 3 years. With the diagnosis of arachnoid cyst or Rathke's cleft cyst, bas ed on MRI findings of intra-and supra-sellar cyst with CSF intensity, he su ccessfully underwent transsphenoidal surgery without evidence of intra-oper ative CSF leakage. He developed CSF rhinorrhea one week later. This needed another operation for sellar floor repair. The pathomechanism of this delay ed onset is explained as follows. Incomplete or one-way communication of su barachnoid space to cyst cavity, unrecognized during surgery, might cause d elayed onset of CSF rhinorrhea. By using MRI, identification of the residua l gland, which was compressed posteriorly, is useful for differentiating an arachnoid cyst from other cystic lesions. In highly suspect cases, even wi thout evidence of intra-operative CSF leakage, peri-operative measures to p revent occurrence of postoperative CSF rhinorrhea are required.