Hydroxyapatite Resurfacing-only Technique for Sigmoid Sinus Dehiscence: Patient Demographics and Outcomes

Introduction: The etiology of bony dehiscence in sigmoid sinus wall anomalies (SSWA) in symptomatic pulsatile tinnitus is unknown. Clinically, the efficacy and complications of sigmoid sinus resurfacing (SSR) with hydroxyapatite bone cement (HAC) without venous manipulation remains elusive.

Methods: Patients with pulse-synchronous tinnitus from 2020-2024 who underwent SSR with HAC were included. Average sigmoid sinus plate thickness and mastoid cortex thickness (reference) was measured using calipers at 12mm intervals on high resolution (0.6 mm thickness) axial temporal bone CT and compared to age-, sex-, and BMI-matched CT images of cochlear implant or otosclerosis control patients. SSR involved placing 1-2mm layer of HAC over dehiscences without sigmoid sinus manipulation. Student t-test and Cohen’s-d was calculated with significance set at < 0.05.

Results: Seven patients with unilateral pulse-synchronous tinnitus (all female) had an average (SD) age of 38.7 (7.0) years and average BMI of 37.3 (8.9) kg/m2 underwent SSR with HAC. The average (SD) sigmoid sinus bone thickness on the ipsilateral side was significantly thinner than the contralateral side [0.39 (0.46) mm vs. 1 (0.58) mm, p< 0.001, Cohen’s-d = 1.17] and was also significantly thinner than matched control patients [0.39 (0.46) mm vs. 1.45 (0.44) mm, p< 0.001, Cohen’s-d = 2.35]. There was no difference in mastoid cortex thickness between symptomatic and control ears [2.28 (0.73) mm vs 2.35 (0.88) mm, p=0.73]. All operated patients experienced complete resolution of symptoms after surgery without complications.

Conclusions: Isolated thinning of the sigmoid sinus plate is seen in patients with SSWA and symptomatic pulse-synchronous tinnitus, implicating a progressive pathology. SSR with HAC without venous sinus manipulation is a safe and effective symptomatic treatment.