Skull Base Abnormalities Associated with Spontaneous Cerebrospinal Fluid Leakage

Objective: Spontaneous cerebrospinal fluid (CSF) leakage is a rare condition. Diagnosis comes late and often becomes part of discussion after recurrent meningitis.

We report on a series of individual cases associated with congenital skull base abnormalities.

Patients/Materials and Methods: Seven patients with spontaneous CSF fistulas are reported. Diagnostic procedures used were high-resolution CT; CT cisternography; and, in special cases, MRI cisternography with gadolinium, as well as intrathecal fluorescein application. By these means, the pathologies could be clearly detected.

Each treatment was discussed between ENTs and neurosurgeons.

Results: In four cases a persisting Sternberg's canal was found, and in two additional cases besides the Sternberg's canal a pseudo tympanomeningeal duct (Hyrtl's fissure) was present. These patients had additional bony defects of the skull base and/or meningoceles. Another patient had a defect at the cribriform plate and multiple other basal defects. This case presented with pseudotumor cerebri.

Surgical treatment for each patient was carefully and individually planned and was effective in all cases but one.

Conclusion: Spontaneous CSF leakage is potentially a life-threatening condition. Malformations and abnormalities of the skull base must be taken into account. The different pathways of spontaneous CSF leakage should be clearly understood and carefully examined .Besides the Sternberg's canal and Hyrtl's fissure, a new type of spontaneous fistula along the glossopharyngeal nerve is described. Combinations of abnormalities are possible.