Rhinorrhea and pneumocephalus after cerebrospinal fluid shunting. The role of lateral extensions of the sphenoid sinus.

Pneumocephalus is usually seen after trauma or neurologic surgery. A rare presentation is after cerebrospinal fluid (CSF) shunting for rhinorrhea. This may be a manifestation of shunt malfunction or of the failure to close a preexisting fistulous tract. A common site of failure is the sphenoid sinus, where CSF may leak from a dehiscence in the middle cranial fossa floor. These dehiscences often communicate with lateral extensions of the sphenoid. This complication is best managed by craniotomy with direct inspection of the floor of the middle cranial fossa and correction of deranged CSF dynamics.