CTA/V Prevalence And Characteristics Of Bilateral Sigmoid Sinus Dehiscence Among Patients With Pulsatile Tinnitus

Background:Pulsatile tinnitus(PT)is a relatively rare cause of tinnitus.It makes up about 4%of patients with tinnitus,which in turn affects up to 10%of the population.Incidence of abnormal,often treatable,structural findings in patients with PT has been noted to be high,ranging from 44%to 91%.Among which sigmoid sinus dehiscence(SSD)is the most common one,and computed tomographic arteriography and venography(CTA/V)is recommended as the best primary imaging modality in patients with PT,which can evaluate both the bony structure surrounding the ear as well as the vasculature with less risks than would the definitive four-vessel angiography.During the clinical practices,we found that,despite the symptom-side.SSD in the asymptom-side is not uncommon in patients with PT,and bilateral SSD can also be demonstrated in some patients.Most previous studies regarding CTA/N in patients with PT focused on the alterations in the symptom-side,little on the asymptom-side,and none on the bilateral sides of PT patients.Objective:To evaluate the CTA/N prevalence and characteristics of sigmoid sinus dehiscence among patients with pulsatile tinnitus(PT),and to explore the association between the onset of pulsatile tinnitus and the presence of SSD.Methods:Sixty PT patients who underwent CTA/V in our department after exclusion of other reasons that could cause PT were enrolled in this study as the study group,and thirty age and sex-matched patients who underwent non-contrast HRCT for other reasons with a negative imaging diagnosis were enrolled as the control group.Following criteria were utilized for evaluating the extent of sigmoid sinus bony wall erosion:(1)The extent of the focal defect of sinus bony wall(sigmoid sinus dehiscence),maximum transverse diameter(MTD),maximum vertical diameter(MVD);(2)The extent of the adjacent temporal bone thinning;(3)The presence of sigmoid sinus diverticulum(sigmoid sinus dehiscence accompanied by diverticulum).Inter-observer reliability was evaluated by using Pearson Correlation Coefficient(PCC).Chi Square test was utilized for comparing the prevalence of SSD between the symptom-side and the asymptom-side of the study group,and between the latter one and the bilateral sides of the control group.Independent-sample t test was utilized for comparing the extent of the focal defect of sinus bony wall between all the symptom sides and the asymptom sides in the study group,and between the asymptom-side of the study group and the bilateral sides of the control group.Paired-sample t test was utilized for comparing the extent of the focal defect of sinus bony wall and adjacent temporal bone thinning between the symptom-side and the asymptom-side in the study group.For evaluating the association between the extent of the focal defect of sinus bony wall and that of the adjacent temporal bone thinning,PCC was utilized.All reported P values were two-sided,and a P value of less than 0.05 was considered to indicate a statistically significant difference.Results:All the measuremente of MTD,MVD,and the thinness of adjacent temporal bone showed good inter-observer reliability(PCC = 0.932,0.933,0.993,respectively).Chi Square test showed that the prevalence of SSD in the symptom-side of the study group was 78%(47/60 ears),significantly higher than that in the asymptom-side,50%(30/60 ears)(P<0.005),which was significantly higher than that in the bilateral sides of the control group,20%(30/60 ears)(P<0.005).Independent-sample t test showed that the mean values of MTD(0.49±0.23 cm vs 0.35±0.18 cm,P=0.006)and MVD(0.50±0.26 cm vs 0.30±0.15 cm,P<0.001)of all the SSDs in the symptom-side of the study group were significantly larger than those in the control side,and no statistically significant difference significant difference was observed in those between the asymptom-side of the study group and the bilateral sides of the control group(0.35±0.18cm vs 0.36±0.18cm,P=0.897;0.30±0.15cm vs 0.30±0.22 cm,P<0.947).Paired-sample t test showed that compared with the asymptomatic side,the symptomatic had a significantly larger MTD(0.52±0.24cm vs 0.35±0.17cm,P<0.001),MVD(0.57±0.28cm vs 0.29±0.13cm,P=0.001),and a significantly thinner adjacent temporal bone(0.34±0.19cm vs 0.52±0.23cm,P<0.001).Hemi-sided PCC showed a negative correlation between the extent of the focal defect of sinus bony wall and that of the adjacent temporal bone thinning.Conclusion:CTA/V can be utilized as a stable imaging modality for clearly demonstrating the presence of SSD,and the prevalence and extent of SSD on the symptomatic side was significantly larger than those on both the asymptomatic side in the study group and the bilateral-side in the control group,indicating an association between the onset of PT and the presence SSD.In addition,the prevalence of SSD on the asymptomatic side in the study group was significantly higher than that on the bilateral-side in the control group,indicated that some primary etiology that can create hypertension in the cranial venous system existed in part of PT patents,giving rise to higher prevalence on both the the symptomatic and the asymptomatic sides in the study group,which deserves more investigation in the future.