CT And Finite Element Model Study Of Venous Pulsatile Tinnitus

Part1.Incidence of Vascular Anomalies and Variants in UnilateralVenous Pulsatile Tinnitus Based on Dual-PhaseContrast-Enhanced CTObject: To evaluate the incidence of various vascular anomalies and variants on thePT side and determine whether or not these anomalies and variants on the PT side ofeach patient are multiple or single.Methods: The dual-phase contrast-enhanced CT (DP-CECT) images of242patientswith unilateral venous PT were retrospectively reviewed. The vascular anomalies andvariants on the symptomatic side and asymptomatic side were analyzed respectively.Data were tested to compare the incidences of anomalies or variants on each side. Thenumber of anomalies and variants on the symptomatic side in each patient wascalculated.Results:(1) Of all patients, one hundred and seventy patients (170/242) had morethan one anomaly or variant on the symptomatic side while58patients (58/242) hadonly one anomaly or variant with radiologic studies. Only14patients were normal.(2)There was statistically significant difference in the incidence of a dehiscent sigmoidplate (symptomatic side,209cases; asymptomatic side,32cases; P <0.001), a lateralsinus stenosis (symptomatic side,135cases; asymptomatic side,108cases; P=0.014),a high jugular bulb(symptomatic side,114cases; asymptomatic side,39cases; P<0.001), a sigmoid sinus diverticulum (symptomatic side,84cases; asymptomaticside,5cases; P <0.001), a jugular bulb diverticulum (symptomatic side,33cases;asymptomatic side,5cases; P <0.001), a dehiscent jugular bulb (symptomatic side,33cases; asymptomatic side,4cases; P <0.001) and a large emissary vein (symptomatic side,10cases; asymptomatic side,1cases; P=0.006) between the symptomatic sideand asymptomatic side, except for a sinus thrombosis (symptomatic side,3cases;asymptomatic side,0cases; P=0.249), and a petrosquamosal sinus (symptomatic side,2cases; asymptomatic side,2cases; P=1.000)(3)The most frequent anomaly orvariant on symptomatic side in this study was a dehiscent sigmoid plate (86.4%),followed by a lateral sinus stenosis (55.8%), a high jugular bulb (47.1%), a sigmoidsinus diverticulum (34.3%), a jugular bulb diverticulum (13.6%), a dehiscent jugularbulb (13.6%), a large emissary vein (4.1%), a sinus thrombosis (1.2%), and apetrosquamosal sinus (0.8%).Conclusions: Preliminary findings suggest that the various vascular anomalies andvariants, especially a combination of vascular anomalies and variants, could be thecause of unilateral venous PT. Part2.CT Imaging Analysis on Sigmoid Sinus DehiscenceObject: To evaluate the CT imaging features of sigmoid sinus dehiscence (SSD)among patients with and without pulsatile tinnitus (PT) for further investigation in themechanism of SSD with and without occurrence of PTMethods:(1)Firstly, twenty two unilateral venous PT patients with bilateral SSDwere enrolled in this study. The maximum horizontal and vertical diameter, area andlocation of SSD on CT images were assessed and compared between the symptomaticside and asymptomatic side (2) The CT images of209(209ears) SSD patients withunilateral venous PT and75(79ears) SSD patients without PT were retrospectivelyreviewed and the maximum horizontal and vertical diameter, area and location of SSD were assessed and compared between the two groups.(3) The CT images of28unilateral SSD PT patients confirmed by surgery and28age-and sex-matched SSDpatients without PT were retrospectively reviewed and the maximum horizontal andvertical diameter, area and location of SSD were assessed and compared between thetwo groups.Results:(1) In22unilateral venous PT patients with bilateral SSD, SSD on thesymptomatic side were significantly more likely to have a larger maximum horizontaland vertical diameter [(6.18±2.31)mm;(5.63±2.50)mm] and area [(29.58±20.60)mm2]than SSD on asymptomatic side [(3.54±1.31)mm;(3.60±1.08)mm;(10.62±6.11)mm2](P<0.05). There was no statistically significant difference in the location of SSD insigmoid wall between the symptomatic side and asymptomatic side (with upperportion,13vs.6; middle portion,2vs.5; lower portion,7vs.11)(P>0.05).(2) ThePT group had significantly larger maximum horizontal and vertical diameter[(5.28±1.73)mm;(5.41±2.05)mm] and area[(23.35±13.29)mm2] than the non-PTgroup [(2.96±1.16)mm;(2.79±1.35)mm;(7.02±5.15)mm2](P<0.05). There wasstatistically significant difference in the location of SSD in sigmoid wall between thetwo groups (with upper portion,80vs.16; middle portion,10vs.9; lower portion,119vs.54)(P<0.05).(3) SSD PT group had significantly larger maximum horizontaland vertical diameter [(6.25±1.76)mm;(6.20±2.24)mm] and area [(31.55±16.99)mm2]than the gender-and age-matched non-PT group [(3.08±1.42)mm;(2.51±1.05)mm;(6.65±4.99)mm2](P<0.05). There was statistically significant difference in thelocation of SSD in sigmoid wall between the two groups (with upper portion,12vs.3;middle portion,0vs.3; lower portion,16vs.22)(P<0.05).Conclusions: SSD can occur in PT and non-PT patients. Preliminary findingsindicates that there may be a potential correlation between the maximum horizontaland vertical diameter, the area of SSD and the severity of PT symptom. The superior and lower portion of sigmoid wall was mostly involved by SSD no matter with orwithout PT. Part3.Finite Element Model and Mechanism Study on SigmoidSinus Dehiscence TinnitusObject: To establish2D finite element models of sigmoid sinus dehiscence tinnituswith different bone plate thickness and dehiscence size and to investigate thecorrelation between bone plate thickness, length of dehiscence and the severity of PTsymptom.Methods: Base on high-resolution CT images of a sigmoid sinus dehiscence tinnituspatient,2D models with different bone plate thickness (0mm,0.25mm,0.5mm, and1mm) and dehiscence sizes (0.5mm,1mm,2mm, and4mm) were simplifiedlyrendered respectively on SolidWorks software. After undergoing discretizationprocess, pretreatment process and being uploaded blood flow data of a pulsatiletinnitus patient,2D finite element models with different bone plate thickness anddehiscence sizes were established respectively. The maximum vibration amplitude ofouter tissue surface of different2D finite element models were monitored andcompared.Results:(1) In bone plate thickness group, the finite element model with0mm boneplate thickness had the largest maximum vibration amplitude than others. There wasno obvious difference in maximum vibration amplitude between0.25mm model and0.5mm model. The finite element model with1mm bone plate thickness had the lowest maximum vibration amplitude.(2) In dehiscence size group, the finite elementmodel with0.5mm dehiscence size had the lowest maximum vibration amplitude thanothers. There was no obvious difference in maximum vibration amplitude among the1mm model,2mm model and4mm model.Conclusions: A bone dehiscence is the key factor of transmission of PT sound. Thereis a potential correlation between bone dehiscence size and transmission or severity ofPT to some extent.