Venous Sinus Compromise after Pre-sigmoid, Transpetrosal Approach for Skull Base Tumors: A Study on the Asymptomatic Incidence and Report of a Rare Dural Arteriovenous Fistula as Symptomatic Manifestation

Introduction: The sigmoid sinus is routinely exposed and manipulated during pre-sigmoid, transpetrosal approaches to the skull base, but there is scant data available on the incidence of venous sinus compromise after surgery. We encountered a dural arteriovenous fistula as a result of sigmoid sinus occlusion and examined the incidence of venous sinus thrombosis or narrowing after transpetrosal surgeries.

Methods: We performed a retrospective analysis of a series of patients treated by the senior surgeons (WCJ, MH, HJK), who underwent either a posterior petrosectomy or translabyrinthine approach for various skull base tumors. Fifty-five patients were identified. Three patients were lost to follow up and had insufficient data to analyze. For all others, all available clinical and radiographic data were thoroughly examined in each patient.

Results: Of the 52 available patients, the histopathological diagnosis was meningioma in 13 and vestibular schwannoma in 34. The remainder were a variety of other tumors. Five patients were discovered post-operatively to have a narrowed or constricted sigmoid sinus ipsilateral to the surgery, whereas another five patients were diagnosed with asymptomatic sinus thrombosis either in the transverse or sigmoid or both. In one of these patients, the venous sinus later spontaneously recanalized. None of these patients experience symptoms directly related to the venous sinus compromise, nor did they require anti-coagulation. However, there was one additional patient who complained of pulsatile tinnitus two years after surgery, and the subsequent work-up revealed an occlusion of the ipsilateral sigmoid sinus and a dural arteriovenous fistula, fed from the anterior, posterior and external carotid circulations. There were no instances of ischemic or hemorrhagic complications related to sinus complications.

Discussion: In ~1 out of 5 patients who underwent a pre-sigmoid, transpetrosal approach, the ipsilateral venous sinus system was affected. There was only one symptomatic complication related to the sigmoid sinus occlusion, which ultimately required treatment. Since the caliber of the sinus can change with time, and occluded sinuses can later recanalize, a prospective study would be useful to examine the fate of the venous sinus system immediately after surgery and for the long-term.

Fig. 1 Dural arteriovenous fistula involving the right sigmoid sinus with feeders from a) the posterior, b) the anterior, and c) the external carotid circulations. The flow into the transverse sinus is retrograde and the distal sigmoid sinus is occluded.