Spontaneous submucosal sphenoidal fistula discovered intraoperatively. A case report

Skull base spontaneous cerebrospinal fluid fistulas have been recently recognized as secondary to pseudotumor cerebri. In most cases, they occur in the ethmoid region and the sphenoid bone which is much less affected. Regardless of their etiology, the clinical manifestation of skull base fistulas is usually the same and includes a rhinorrhea and less frequently an otorrhea. We report a case of a cryptic sphenoid cerebrospinal fluid fistula discovered intraoperatively during the excision of a pituitary ACTH-secreting microadenoma (2mm in diameter).

A 54-year-old female was admitted to our neurosurgery department for Cushing's disease due to a pituitary microadenoma. Six months prior to admission, she complained of severe fatigue, polyphagia and weight gain. Clinical examination revealed central obesity with a body mass index of 45kg/m(2) and other symptoms suggestive of Cushing's disease. Hormonal tests and a MR scan revealed a pituitary ACTH-secreting microadenoma. During the operative procedure via a transnasal approach, her nasal and sphenoid sinus mucosa appeared unusually edematous. After removal of the latter in order to approach the sellar floor, a millimetric hole in the bone at the level of the optic groove was visualized which let out cerebrospinal fluid under pressure without interruption. The microadenoma was macroscopically completely removed without any cerebrospinal fluid coming from the pituitary surgical cavity. The closing procedure of the sphenoid groove millimetric opening was performed by injecting fibrin glue and a lumbar drain was placed indwelling for four days.

This case report describes a cryptic sphenoid submucosal cerebrospinal fluid fistula in a patient with Cushing's syndrome. This type of case raises the question of the natural evolution of the skull base cerebrospinal fluid fistula from its formation to an externalization such as rhinorrhea.