Objective and importance: Four cases of spontaneous cerebrospinal fluid rhinorrhea caused by communication between the subarachnoid space of the middle cranial fossa and a lateral extension of the sphenoid sinus are presented. The cause and management of this unique type of cranial base defect are discussed.
Clinical presentation: During the past 10 years, four patients referred to our institution with atraumatic cerebrospinal fluid fistulae were observed to have temporal encephaloceles (encephalomeningoceles) traversing the floor of the middle cranial fossa. Three of the patients had previously undergone unsuccessful transnasal attempts to repair their fistulae by obliteration of the sphenoid sinus. The fourth patient presented before undergoing any treatment. No patient had associated hydrocephalus or tumor. Preoperative computed tomographic cisternograms revealed that all fistulae involved a lateral extension of the sphenoid sinus into the floor of the middle cranial fossa.
Intervention: After definitive localization, each patient was operated on transcranially through an anterior middle cranial fossa approach with extradural and/or intradural exploration. The associated temporal encephalocele was amputated or disconnected, and the dehiscent dura and middle cranial fossa floor defect were oversewn and packed with autogenous tissue, respectively.
Conclusion: The surgical treatment of cerebrospinal fluid rhinorrhea secondary to middle fossa encephalocele associated with lateral extension of the sphenoidal sinus differs from the surgical strategy for more medial sphenoidal fistulae. Fistulae involving a lateral extension of the sphenoid sinus require a transcranial approach for direct visualization and obliteration of the defect, whereas fistulae involving the central portion of the sinus may be successfully obliterated transsphenoidally.