Abstract
Pulsatile tinnitus (PT) caused by enlarged oblique occipital sinus (OOS) and resultant diverticulum/dehiscence of the sigmoid-jugular wall has not been described in previous literature. This study recruits one case of PT induced by ipsilateral enlarged OOS and sigmoid-jugular wall diverticulum (case 1) alongside one case of PT induced by ipsilateral enlarged OOS and sigmoid-jugular wall dehiscence (case 2). Various radiologic and computational techniques including computed tomography (CT), magnetic resonance (MR) imaging, Doppler ultrasound, and computational fluid dynamics (CFD) simulation were implemented. Transmastoid sinus wall reconstruction was performed on case 1 with a large sigmoid-jugular diverticulum potentially traumatizing the facial nerve canal. Contrast-enhanced CT or MR venogram images coupling with three-dimensional reconstructed are advantageous in revealing the covert route of OOS that runs under the cerebellum and drains directly into jugular bulb (JB) region. PT in case 1 was successfully eliminated after transmastoid sinus wall reconstruction surgery. Tinnitus handicap inventory score in case 1 reduced from 70 to 0. The ipsilateral jugular outflow mean velocity (Vmn) and flow volume (FVOL) were 42.5 cm/s and 25.9 g/s (case 1 prior to surgery) and 56.6 cm/s and 41.2 g/s (case 2), respectively. Based on CFD simulation, the peak flow velocity in OOS was 1.85 m/s and 2.1 m/s, the wall pressure of the diverticular dome and dehiscence area of the SS-JB wall was 1724.7 Pa and 369.8 Pa in case 1 and 2, respectively. Enlarged OOS caries greater flow kinetic energy that possibly induces sigmoid-jugular wall diverticulum/dehiscence; transmastoid surgical method is safe and therapeutically effective against PT induced by enlarged OOS.
Introduction
Vascular pulsatile tinnitus (PT) or pulse-synchronous tinnitus is the auditory perception of vascular sounds in line with the cardiac rhythm (1). The most common type of vascular PT is venous PT (2), which is characterized by the reduction or elimination of PT sound when the ipsilateral internal jugular vein (IJV) is compressed (3).
Venous PT requires prudent examination of venous vasculature and the surrounding osseous structure near the hearing apparatus. The causes of venous PT include sigmoid sinus (SS) wall anomalies, high-riding jugular bulb (JB) dehiscence/diverticulum, transverse-SS enlargement, and mastoid emissary vein (4, 5). The symptomology and radiologic signs in patients with venous PT overlap with those in patients with idiopathic intracranial hypertension, a clinical entity characterized by increased intracranial pressure with unknown cause (4). Hypothesized mechanisms of the cause of PT relate to (1) osseous defects surrounding the pulsating vessel that produce vibroacoustic noises, and (2) increased flow kinetic energy that engenders hydroacoustic vascular sounds (6). The produced mechanical sound is transmitted predominantly through the air-conduction pathway to the inner ear, resulting in the perception of PT (5–7).
The occipital sinus is a small venous channel found in 64.5%–95% of cadaveric specimens and normal subjects (8). The length and inner diameter of an occipital sinus measure between 15 and 70 mm and 0.33–7.06 mm, respectively, and age-related regression may occur (9). It is usually positioned underneath the torcular herophili at the midline near the attachment of the falx cerebelli or deviates on the left or right side with two or more cranial or caudal divisions. In a large case series, Kobayashi et al. found that 11.9% of the occipital sinus communicates with or branches into the SS (10). This type of occipital sinus is called oblique occipital sinus (OOS). However, despite previous reports, the epidemiology of a large OOS that runs directly into the SS or the JB remains unknown.
This study reports unprecedented causes of venous PT caused by ipsilateral OOS and sigmoid-jugular wall anomalies (SJWAs) invading the mastoid cavity and sheds light on the mechanism of this newly discovered phenotype of venous PT.
Case presentation
Case report 1
A 43-year-old female patient with persistent right sided PT for 1 year as the solitary symptom presented to our facility in June 2022. Her PT was abolished when the ipsilateral IJV was compressed. Endoscopic examination revealed a normal tympanic membrane in both ears. Pure-tone audiometry showed no hearing loss on either side. Computed tomography (CT) revealed a right-sided SS-jugular diverticulum invading the lower mastoid cavity, potentially traumatizing the facial nerve and nearly exiting the mastoid apex (Figure 1). The closest distance between the dome of the diverticular and facial nerve canal was 3 mm. Magnetic resonance (MR) images revealed an enlarged OOS running into the lower curve of the right-side SS, with ipsilateral intrinsic transverse sinus stenosis and contralateral transverse sinus hypoplasia. A diverticulum had formed between the lower curve of the SS and JB. Fundus examination showed presence of bilateral papilledema. The tinnitus handicap score was 70. Computational fluid dynamics (CFD) was performed to analyze sinus flow hemodynamics (see Supplementary Digital Content S1 for CFD methodology). Transmastoid surgical resurfacing of SJWAs was performed to resolve the PT (see Figure 2 for a detailed description of the surgical procedures).
Figure 1
Figure 2
Case report 2
A 35-year-old female patient complained of persistent right-sided PT for a duration of 1.5 years visited our clinic in October 2019. Her PT was silenced during ipsilateral IJV compression. Pure-tone audiometry revealed no hearing loss in either ear. Endoscopic examination revealed insignificant findings on both sides. CT images showed discontinuity and absence of bone structure in the SS-JB wall (Figure 3). MR resonance imaging revealed an enlarged OOS anastomosed with the JB and bilateral transverse sinus hypoplasia. Fundus examination results were normal. The tinnitus handicap index score was 22. CFD simulation was performed. Since the patient chose not to undergo surgical treatment, an annual radiologic follow-up was advised, and continuous online medical consultation was provided.
Figure 3
Results
The ipsilateral jugular outflow mean velocity (Vmn) and flow volume (FVOL) were 42.5 cm/s and 25.9 g/s (case 1) and 56.6 cm/s and 41.2 g/s (case 2), respectively. The postoperative ipsilateral Vmn and FVOL of case 1 were 44.1 cm/s and 26.9 g/s. CFD analysis found that the peak velocity in the enlarged OOS was 1.85 m/s and 2.1 m/s, the wall pressure of the diverticular dome and SS-JB wall was 1724.7 Pa and 369.8 Pa in case 1 and 2, respectively (Figure 4).
Figure 4
PT was eliminated after surgery in case 1. The cross-sectional diameter of the diverticular and SS lumen was reduced from 1.49 to 5.4 mm, rendering a smooth SS silhouette. The postoperative tinnitus handicap index score was 0. The patient had ear numbness and a plugged ear after surgery. There was no recurrence of PT or symptoms related to increased intracranial pressure during the 6-week follow-up.
Discussion
To the best of our knowledge, PT related to SJWAs caused by an enlarged OOS has not been described in the literature. An enlarged OOS can be overlooked owing to its covert route underneath the cerebellum and direct drainage into the SS or JB. In this study, OOS dominated over the ipsilateral or bilateral hypoplastic transverse sinus and carried excessive flow kinetic energy that exerted flow pressure onto the lower curve of the SS wall. The onset of PT in these two cases likely resulted from the formation of SJWAs, since the presence of OOS is congenital (8, 9). This inference is akin to the mechanism of PT caused by SS wall anomalies, which frequently occur on the dominant side of the transverse-sigmoid sinus junction. Additionally, the Venturi effect was also evidenced by the middle to distal stenosis of the OOS, producing a jet flow effect similar to that observed in transverse sinus stenosis (5). A more severe degree of osseous wall erosion and vascular wall protrusion was observed in these two cases, which is conceivably related to the high flow kinetic energy carried by the enlarged OOS.
According to the jugular Doppler measurement, the ipsilateral FVOL of subjects with enlarged OOS was 1.5∼2.5 times larger than those with venous PT caused by SS wall anomalies (7). Additionally, CFD indicates that the vortex generated at the intersection of the OOS and SS increased the regional flow pressure gradient. Given the impaired flow condition, patients with an enlarged OOS should be suspected of having increased intracranial pressure, especially when bilateral hypoplastic transverse sinus is present. Therefore, surgical attempts to occlude the OOS lumen or significantly reduce the venous pool volume may be unwise, whereas the stenting of OOS stenosis has been shown therapeutically effective, although the presence of SJWAs was not evaluated in that study (11).
PT secondary to SJWAs induced by an enlarged OOS can be treated with transtemporal sinus wall reconstruction surgery. Unlike transverse-SS junction diverticulum or dehiscence, SJWAs caused by an enlarged OOS can be more strenuous to operate on because of its location adjacent to vital anatomical structures. Owing to the fragile diverticulum surface, separating the diverticular and osseous walls (typically the medial portion) most likely lacerates the vascular surface and causes considerable hemorrhage. Because SJWAs are located at the lower curve of the SS, we tailored the repair material and inserted it into the epidural space to stanch bleeding during the reduction of the diverticulum. To avoid sinus overcompression or the entrance of hemostat debris into SS, haemostatic materials should be customized with certain malleability, robustness, and retractability; in our case, this was a large piece of temporalis muscle with the solidified artificial dura mater fixated on the muscular edge sewn with suture. Lastly, regarding strong OOS flow impaction, we reduced the diverticulum and applied multilayer materials to prevent further invasion of the diverticular wall into other anatomical structures and preclude the hydroacoustic/vibroacoustic sound transmission in the mastoid cavity.
Conclusion
Enlarged OOS caries greater flow kinetic energy (with 1.5∼2.5 times larger FVOL compared to those with venous PT without the afferent enlarged OOS) that possibly induces SJWAs. Although the presence of enlarged OOS is rare, this study reveals that the transmastoid surgical method safe and therapeutically effective against PT induced by enlarged OOS and resultant diverticulum/dehiscence of the sigmoid-jugular wall.
Statements
Data availability statement
The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.
Ethics statement
The studies involving human participants were reviewed and approved by Ethical Committees of the Eye, Ear, Nose, and Throat Hospital in Shanghai, China. The patients/participants provided their written informed consent to participate in this study.
Author contributions
Y-LH designed the study, drafted the manuscript, and performed the computational analyses in this study. SW performed radiologic examinations and post-analysis of radiologic data. WW is the lead surgeon who discovered the pathology, performed the operation, and supervised this study. All authors contributed to the article and approved the submitted version.
Funding
This study was supported by Science and Technology Innovation Plan of Shanghai Science and Technology Commission (no. 22Y11902200).
Acknowledgments
Y-L H would like to thank WQW for sharing his discovery and constantly being attentive to this phenotype of venous PT.
Conflict of interest
The reviewer [SL] declared a shared parent affiliation with the authors to the handling editor at the time of review. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fsurg.2022.1014649/full#supplementary-material.
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Summary
Keywords
pulsatile tinnitus, occipital sinus, oblique occipital sinus, diverticulum, dehiscence
Citation
Hsieh Y-L, Wang S and Wang W (2023) Case Report: Venous pulsatile tinnitus induced by enlarged oblique occipital sinus and resultant diverticulum/dehiscence of the sigmoid-jugular wall. Front. Surg. 9:1014649. doi: 10.3389/fsurg.2022.1014649
Received
08 August 2022
Accepted
01 November 2022
Published
06 January 2023
Volume
9 - 2022
Edited by
Han Lv, Capital Medical University, China
Reviewed by
Jae-Jin Song, Seoul National University Bundang Hospital, South Korea Shihong Li, Fudan University, China
Updates
Copyright
© 2023 Hsieh, Wang and Wang.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Wuqing Wang wwuqing@eent.shmu.edu.cn
These authors share first authorship
Specialty Section: This article was submitted to Otorhinolaryngology - Head and Neck Surgery, a section of the journal Frontiers in Surgery
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.