|Year : 2019 | Volume
| Issue : 4 | Page : 184-187
Sigmoid sinus diverticulum and dehiscence: Diagnosis and management
H Shameer Ahamed1, Ajay Philip1, Aparna Irodi2, Anjali Lepcha1, Shyamkumar Nidugala Keshava2
1 Department of ENT Unit-4, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Radiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India
|Date of Submission||10-Nov-2018|
|Date of Acceptance||26-Mar-2019|
|Date of Web Publication||4-Dec-2019|
Dr. Ajay Philip
Department of ENT Unit.4, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Introduction: Sigmoid sinus diverticulum (SSD) is a relatively rare vascular disorder characterized by a dilated sac in the sinus wall protruding into the mastoid cells. It may be associated with SSDe-Sigmoid sinus plate dehiscence (SSDe); however, SSDe can occur in isolation too. SSD may be associated with prediverticular venous sinus stenosis (SS) and commonly presents as pulsatile tinnitus (PT). Aim: This study aims to present a series of patients who were diagnosed and managed for SSD and SSDe and discuss their treatment options. Methods: A retrospective chart review was carried out between January 2016 and August 2018, and all patients presenting with PT and diagnosed with SSD and or SSDe were included in this study. Results: We had six patients who were diagnosed with SSD and SSDe during this time frame. High-resolution computed tomography and magnetic resonance venogram were used for the diagnosis. In addition, cerebral angiogram was done for 2 patients who had prediverticular stenosis of the sinus. Transmastoid decompression and repair of SSD gave excellent relief from tinnitus in one patient. Conclusion: SSD and SSDe are treatable causes of PT. SSD may be associated with a prediverticular venous SS. A prediverticular high-pressure gradient stenosis should be managed before decompression and repair of SSD.
Keywords: Angiogram, prediverticular venous sinus stenosis, pulsatile tinnitus, sigmoid sinus dehiscence, sigmoid sinus diverticulum
|How to cite this article:|
Ahamed H S, Philip A, Irodi A, Lepcha A, Keshava SN. Sigmoid sinus diverticulum and dehiscence: Diagnosis and management. Indian J Otol 2019;25:184-7
| Introduction|| |
Tinnitus is a frequent symptom of patients in the ENT outpatient clinic. Pulsatile tinnitus (PT) is a relatively rare subset of tinnitus, which comprises about 4% of all patients who present with tinnitus. Causes of PT include arterial causes such as arterial dissection, atherosclerosis, and fibromuscular dysplasia and venous causes such as benign intracranial hypertension, arteriovenous malformations around the ear, glomus tumors and sigmoid sinus anomalies, conditions causing hyperdynamic circulation, and hyperpneumatized temporal bones. Sigmoid sinus anomalies causing tinnitus include (a) sigmoid sinus diverticulum (SSD), (b) sigmoid sinus aneurysm, and (c) SSDe-Sigmoid sinus plate dehiscence (SSDe).
The imaging workup of patients with PT includes a high-resolution computed tomography (HRCT) of temporal bone, a CT, or magnetic resonance (MR) angiogram/venogram. We present a series of five cases who presented with PT caused by SSD and SSDe and describe the imaging findings and management in such patients.
This study aims to discuss the presentation, diagnosis, and management of SSD and SSDe presenting with PT.
| Methods|| |
This study was based in a tertiary care referral hospital. A retrospective chart review was carried out between January 2016 and August 2018 of all patients who presented to the otology unit of ENT with symptomatic SSD or SSDe or both. The presentation, diagnosis, and management of these cases were noted.
| Results|| |
We had six patients who presented with PT in this period and were diagnosed with SSD/SSDe or both. There were five females and one male in the group. All patients had their right ear affected with tinnitus that was pulsatile in character. The mean duration of symptoms was 26.8 months (ranging from 7 months to 3 years). The details of these six patients are enumerated in [Table 1].
|Table 1: Demographic details of the individuals with their corresponding radiological finding|
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All patients had a normal otoscopic evaluation on the symptomatic side and had a normal pure tone audiogram. Of the six opted for surgical exploration, the remaining five were not keen on any intervention after they understood the cause of their tinnitus. They were counseled and asked to report whenever necessary. We describe in detail patient 2 who underwent surgery and patient 4 who had SSD with significant transverse sinus narrowing.
Patient 2 was a 43-year-old female who presented with right-sided continuous PT of 8 months' duration. Her audiological and routine blood investigations were normal. HRCT temporal bone [Figure 1]a and [Figure 1]b showed a small SSD on the right side with a bony defect. Contrast-enhanced MR imaging (MRI) [Figure 1]c and [Figure 1]d and MR venogram [Figure 2]a confirmed a 9 mm × 4 mm diverticulum with suspicion of stenosis in prediverticular right transverse sinus.
|Figure 1: Focused sagittal (a) and axial (b) high-resolution computed tomography images of the temporal bone at the level of mastoid air cells show the dehiscence in the sigmoid plate with sigmoid sinus diverticulum projecting into the mastoid air cells. Sagittal contrast-enhanced magnetic resonance imaging images (c and d) at the same location as (a) showing the sigmoid sinus (thin double arrows) and sigmoid sinus diverticulum, measuring approximately 9 mm × 4 mm, protruding anteriorly (thick arrow)|
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|Figure 2: Magnetic resonance venogram (a) and left internal carotid angiogram in venous phase (indirect venography), frontal (b), and lateral (c) views demonstrating the diverticulum at the junction of right transverse–sigmoid dural sinuses (arrow), measuring 9 mm × 4 mm. Magnetic resonance venogram showed mild prediverticular narrowing in distal transverse sinus (curved arrow in a). However, there was no significant pressure gradient at this site during direct venography, indicating that there was no significant stenosis|
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As part of the management, a cerebral angiogram [Figure 2]b and [Figure 2]c with pressure measurement was done which showed a right SSD of 9 mm × 4 mm size with mild stenosis in the right transverse sinus with no significant pressure gradient across the stenosis. The left transverse and sigmoid sinus were normal.
Since there was no significant pressure gradient across the stenosis, the patient was planned for surgery. A transmastoid approach and decompression of the SSD with reconstruction of the bony defect with fascia, bone pate, and fibrin sealant (Tisseel) was carried out. There were no surgical complications, and the PT disappeared postsurgery. She has been on regular follow-up with no recurrence of the symptoms 1 year later. [Figure 3]a, [Figure 3]b, [Figure 3]c depict the intraoperative steps.
|Figure 3: (a) Sigmoid sinus plate thinned sigmoid sinus diverticulum exposed (black arrow). (b) Multilayered reconstruction using temporalis fascia, bone chips, and pate. (c) Fibrin sealant applied over the reconstruction |
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A 34-year-old female presented with complaints of right-sided PT, which was continuous in nature for 8 months' duration.
Her audiogram and her routine blood investigations were normal. HRCT temporal bone showed a small SSD on the right side with thinned-out and dehiscent sigmoid sinus plate [Figure 4]a, [Figure 4]b, [Figure 4]c.
|Figure 4: Axial (a), coronal (b), and sagittal (c) high-resolution computed tomography images of the temporal bone showing aright sigmoid sinus diverticulum (arrows) in direct contact with the mastoid air cells|
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An MR venogram [Figure 5]a showed a 15 mm × 10 mm right-sided SSD with high-grade stenosis of the transverse–sigmoid sinus junction [Figure 4]b.
|Figure 5: Magnetic resonance venogram (a), left common carotid angiogram in venous phase (indirect venography), lateral (b) and frontal (c) views, showing right sigmoid sinus diverticulum (arrow), measuring approximately 10 mm × 15 mm with a prediverticular stenosis (curved arrow). Right sigmoid sinus direct venogram through ipsilateral internal jugular access, lateral view (d) showing the sigmoid sinus diverticulum (arrow) and prediverticular stenosis (curved arrow). The pressure gradient was 9 mmHg (13–4 mmHg across the stenosis)|
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Cerebral angiogram [Figure 5]b and [Figure 5]c with pressure measurement [Figure 5]d revealed a 15 mm × 10 mm × 13 mm right SSD with significant narrowing of transverse–sigmoid sinus junction and a pressure gradient (9 mmHg) across the stenosis. The left transverse sinus and sigmoid sinus were hypoplastic.
In view of the significant pressure gradient across the stenosis in patient 4, dilatation/stenting of stenosis followed by transmastoid decompression of SSD and reconstruction of bony wall was planned; however, the patient deferred from further management.
| Discussion|| |
SSD is defined as “protrusion of the sigmoid sinus wall into the mastoid cortex or mastoid air cells.” Some authors may refer to it as aneurysm rather than a diverticulum, although there is no clear consensus to the ideal terminology. SSD may be associated with a bony defect or a prediverticular stenosis (PDS). Sigmoid sinus plate dehiscence (SSDe) is defined as “defect in the bone overlying the sigmoid sinus which results in direct contact of the sigmoid sinus to the mastoid air cells.”
The pathogenesis of SSD is due to the turbulent or nonlaminar blood flow which occurs in the diverticulum. In SSDe, there is loss of the cushion effect of the bone and air cells, which resonates the pulsations from the sinus to the mastoid air cell system to the inner ear., Since SSD may present with a concurrent bony defect, the pathologies are twofold with nonlaminar blood flow and transmission through the mastoid, and therefore, both these should be addressed for complete resolution of symptoms and to prevent recurrence.
There is a female preponderance to SSD according to studies, which is postulated due to the coexisting idiopathic intracranial hypertension which is more prevalent in females. We had five females and one male in our study. About 60% of our patients had SSD, whereas 40% were diagnosed with sigmoid sinus dehiscence. This was in contrast to the descriptive study of 54 patients by Harvey et al. where 39.4% of patients had SSD and 60.6% had sinus wall dehiscence.
Majority of the SSD occur on the right side. It is mainly attributed to the hypothesis that the right jugular bulb and sigmoid sinus are dominant in the majority of the population. All our patients had their right ear affected. Our investigations included an HRCT of the temporal bone (0.625-mm slice thickness with a sharp reconstruction kernel) to identify the bony defect and co-existing SSD, with an additional MRI venogram to delineate the SSD, its size and to detect the presence of a PDS. It would thus be ideal to do both an HRCT and a venogram to identify all possible pathologies. If a PDS is suspected on MR venogram, indirect and direct catheter venogram can be performed to better delineate the diverticulum and measure the pressure gradient across the stenosis to decide on whether the stenosis is significant.
The detection of a PDS is vital to ensure the success of the surgical management as mere treatment of the SSD without addressing the PDS will result in inadequate correction of the underlying pathology, thereby resulting in recurrences or persistence of symptoms in the future.
The measurement of direct venous pressure gradient across the stenosis is also important as a significant pressure gradient will need management of the stenosis before addressing the SSD per se.
The management options for SSD include sigmoid sinus wall reconstruction (91.4%), endovascular procedures (7.9%), and use of endovascular clips and cardiac U-clip (0.7%).
Surgical decompression of the SSD with reconstruction should be done for cases which do not have a significant pressure gradient across the stenosis. For patients with SSD having a PDS with a significant pressure gradient, it is prudent to correct the stenosis by dilatation or stenting, followed by surgical decompression.
Complete exposure of the vascular anomaly by careful drilling is mandatory during surgical decompression so that adequate decompression is possible. Failure to comply will result in high failure rates. Care should be taken to avoid overpacking of the sigmoid sinus dehiscence and maintain the sinus caliber so as to avoid postoperative intracranial hypertension. Following decompression of the SSD, the overlying bony wall or defect should be reconstructed to prevent transmission of sound to the inner ear. Various materials such as temporalis fascia, autologous bone chips, bone pate, and bone cement have been used to obtain a multilayer closure.
| Conclusion|| |
SSD and SSDe are treatable causes of PT, and surgery involves low morbidity, provided such patients are properly assessed before surgery. A combination of CT and MRI with MR venogram is essential to delineate all the components of the pathology, including assessment for a prediverticular venous sinus stenosis (SS). If a venous SS is detected on MRI, cerebral venogram is indicated to measure the pressure gradient across the stenosis, and management differs based on the gradient, i.e., either only transmastoid decompression or dilatation/stenting of the venous SS followed by surgical decompression.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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