Spontaneous Cerebrospinal Fluid Leak through the Posterior Aspect of the Petrous Bone

Abstract

Objective: Spontaneous cerebrospinal fluid (CSF) leak through the posterior fossa aspect of the petrous bone (PF) is very rare. A case series allows analysis of possible etiologies and how they may differ from the more common middle fossa (MF) route of leakage.

Method: A series of 3 patients with PF spontaneous temporal bone CSF leaks is described. High-resolution imaging (CT & MRI) and intraoperative observation characterize the anatomical characteristics of the pathway.

Results: This series of patients did share the demographics typically found in the MF leak population. Two patterns of PF CSF leak were identified: large unilateral with cerebellar encephalocele and bilateral small defects just lateral to the endolymphatic sac. Two out of our 3 patients presented with simultaneous MF and PF leaks suggesting the possibility of a shared etiology, at least in some cases, with a role for increased intracranial pressure.

Conclusion: In spontaneous CSF leaks it is important to evaluate the posterior petrous bone along with the tegmen. The concomitant appearance of MF with PF leaks points out the risk that repair via MF craniotomy could fail to identify a leakage site in the vicinity of the endolymphatic sac.