Zhaohui Liu MD, Presenter: Nothing to Disclose

Zhenchang Wang MD, PhD, Abstract Co-Author: Nothing to Disclose

Shusheng Gong MD, PhD, Abstract Co-Author: Nothing to Disclose

Junfang Xian MD, Abstract Co-Author: Nothing to Disclose

Sigmoid sinus diverticulum presenting as PT, which often originated at the superior curve of sigmoid sinus and the descending sigmoid sinus, usually coexists with dehiscent sigmoid plate and extensive pneumatized temporal bone.

Few studies have focused on sigmoid sinus diverticulum as a cause for PT and only 12 cases have been reported. But, these studies are case reports. Furthermore, sigmoid sinus diverticulum is found occasionally in healthy people and PT was not relieved in some patients with sigmoid sinus diverticulum after surgery. Therefore, CT findings of a large size of samples should be further investigated.

The diverticulum in 15 cases was located on the PT side. Diverticula originated at the superior curve of sigmoid sinus in 11 cases and the descending sigmoid sinus in 4 cases. Diverticula were found on the anterior wall of the sigmoid sinus in 5 patients, on lateral wall in 1 case, and on anterolateral wall in 9 cases. Diverticula focally eroded into the adjacent mastoid air cells in 12 cases and mastoid cortex in 3 cases. The shape of sigmoid diverticula was appeared to be cystiform shaped in 12 cases, polygon shaped in 2 cases and triangular in 1 case. Dehiscent sigmoid plate and extensive pneumatized temporal bone on the PT side was demonstrated in all cases. (Figure 1) Figure 1 A case with right-side PT. Oblique sagittal CT shows a cystiform diverticulum eroded into the mastoid air cells with dehiscent sigmoid plate and hyperpneumatization of temporal bone(arrow).

Previous studies have suggested that PT may be the result of vibration of vessel wall caused by turbulence. But, dehiscent sigmoid plate and extensive pneumatized temporal bone on PT side were showed in all cases in our study, which may be essential conditions of PT elicited by sigmoid sinus diverticulum. Insulation characteristic of sigmoid plate might be destroyed when dehiscent sigmoid plate presents and large mastoid air cells may serve as an amplificator or reduce the ability of blocking sound transmission. Increased transmission of vibration to the cochlea would lead to PT.

Liu, Z, Wang, Z, Gong, S, Xian, J, Sigmoid Sinus Diverticulum Induced Pulsatile Tinnitus: CT Analysis of 15 Cases.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12020434.html