Pulsatile tinnitus secondary to sigmoid sinus diverticulum: A case report

CASE PRESENTATION

A 40-year-old, formerly healthy female presented to our clinic with a 3-year history of right-sided synchronous PT. Tinnitus was perceived to be louder when in a quiet environment and on exertion. Turning the patient’s head to the ipsilateral side relieved her symptoms. The patient did not experience changes in the pitch of the sound over time and did not suffer from hearing loss, vertigo, ear pain, facial weakness, or disturbed sleep. The bruit interfered with her daily activities but did not affect her sleep. The patient gradually developed depression secondary to tinnitus, and was treated with antidepressants. The patient was rated with grade 5 tinnitus based on the tinnitus handicap inventory (THI). There is no history of previous tinnitus. The family history was unremarkable. Physical examination revealed a mildly obese female with a disturbed disposition as a result of her symptoms. Otoscopic examination revealed no abnormalities in either ear. No bruits were detected on auscultation. Tinnitus was relieved on compression of the ipsilateral internal jugular vein. The patient had normal neurological and ophthalmologic function. Pure tone audiometry revealed normal hearing and word discrimination. Routine blood test results were within normal range. A bony defect in the right sigmoid plate with vascular protrusion from the sigmoid sinus was detected on computed tomography (CT) (Fig. 1A.). No other vascular neoplasm, anomaly, or malformation was observed.Treatment plan included obliteration of the SSD using a trans- mastoidal approach to relieve the symptoms and improve the quality of life.

The procedure was performed under general anaesthesia. A curvilinear post-auricular incision was made 1 cm posterior to the post-auricular sulcus. The skin, temporalis fascia, and periosteal flap were elevated. A bluish mass was visible under an operative microscope and the mastoid cortex around this mass was drilled until complete identification of the sigmoid diverticulum (Fig. 2A). This was followed by mastoidectomy and obliteration of the diverticulum. The conchal cartilage and temporalis fascia were used as grafts to obliterate the diverticulum (Fig. 2B). An absorbable haemostatic agent was used to achieve haemostasis. The patient reported that the sounds disappeared immediately after the procedure and was discharged the following day with no adverse reactions. Postoperative venous CT was performed after 3 months, which showed obliteration and reduction of the diverticulum with bone remodelling around the harvested cartilage (Fig. 1B). No recurrence of tinnitus was noted during the subsequent 3-year follow-up. Repeated THI showed grade 1 of tinnitus severity.

DISCUSSION: The perception of noise in the absence of an auditory stimulus is known as tinnitus 1 . When tinnitus is perceived as rhythmic and synchronises with the heartbeat, it is defined as PT 2 . PT can be produced by vascular organs (arteries or veins) or nonvascular organs (neoplasms or middle ear conductive hearing loss) 3 . Sigmoid sinus wall anomalies (SSWA), such as SSD or sigmoid sinus dehiscence (SSDe), are the venous cause of PT in 35% of the cases 1 . Most cases of SSWA have been reported in middle-aged obese females, suggesting a gender predilection 4 . One of the theories behind the epidemiology is that SSWA can be a manifestation of idiopathic intracranial hypertension (IIH), which is common in this sub-group 1 . Prolonged turbulence in sigmoid sinus blood flow eventually leads to SSWA and SSD. Turbulent blood flow and bony erosion can also occur secondary to cerebrospinal fluid (CSF) pulsation and increased intracranial pressure, respectively. The above processes contribute to the pathophysiology of IIH 1 . In addition, most cases of PT occur on the right side, which is the dominant venous system in most populations 5 . This is due to the nonsynchronous development of the venous sinuses during embryonic development 6 . Unilateral dominance of the venous system leads to irregular vessel diameter, resulting in irregular blood flow, followed by PT 7 . Venous PT is eliminated or attenuated when the ipsilateral internal jugular vein is compressed, and the volume is often altered by head positioning 1,5 . Symptoms usually last for several months, and some patients have other symptoms, such as hearing loss or vertigo 1,8 . Otoscopy usually reveals a normal tympanic membrane 5,8–10 . The reported case is in conjunction with the epidemiology and presentation of this disease.

Since SSD is a common cause of venous PT, CT is used for the diagnosis due to its low cost and better visualization of bone anatomy compared to magnetic resonance angiography (MRA) 2 . Most diverticula occur in the sigmoid-transverse junction of the anterior, anterolateral, and lateral walls 5,11 . SSWA is often an incidental finding on CT and is found in 18% of patients undergoing imaging for other symptoms 1 . Concurrent abnormalities include prediverticular stenosis, a high jugular bulb, or superior semicircular canal dehiscence 1,8–10 . There is debate on the role of temporal bone pneumatization in the transmission of sigmoid sinus vibration. All the patients had extensive temporal bone pneumatization in a study reported by Liu et al 11 . They concluded that pneumatization amplifies PT secondary to SSD. In contrast, another study did not show a statistically significant association between the severity of PT and pneumatization of the temporal bone 12 .

The most common treatment options for SSD are sigmoid sinus wall reconstruction (91.4%), endovascular procedures (7.9%), and the use of endovascular clips and cardiac U-clips (0.7%) 4 . The trans-mastoid approach involves reduction of the diverticulum and reinforcement of the sinus bone 13 . Several materials, such as temporalis fascia, autologous bone chips, bone pate, and bone cement, have been employed to achieve multilayer closure 4 . The major surgical complications are extraluminal compression and intravascular thrombosis 2 . Other minor complications include ear fullness and peri-auricular numbness 4 . Endovascular treatment is minimally invasive and can address diverticulum and stenosis but cannot address bony wall defects 10 . Complications of this procedure include stent thrombosis, which requires prolonged anticoagulation therapy and coil migration 4 . A less common treatment method is the retro-sigmoid approach and diverticulum clipping. It is less invasive than other surgical treatments, but no long-term follow-up study has been conducted to date 14,15 .

Trans-mastoid sinus wall reconstruction has been shown to be successful in 90% of the patients 2 . Recurrence is minimal but can occur several years later 4,13 .

CONCLUSION: In conclusion, this is the first report of an SSD-causing PT in Saudi Arabia. Since a delayed diagnosis is associated with morbidity and poor quality of life, physicians should be aware of the vascular causes of PT and include them in the differential diagnosis.

REFERENCES:

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Figure Legends

Figure. 1. Axial computed tomography scan of the brain. (A): preoperative scan which shows a small right bony defect in the inner table of right sigmoid plate (white arrow) containing vascular structure that connected to the sigmoid sinus without obvious connection to any other vascular structure. (B): postoperative scan showing obliteration of the diverticulum with bone remodelling around the harvested cartilage.

Figure. 2. Gross intraoperative view. (A): Well identified sigmoid sinus diverticulum (white arrow). (B): Temporalis fascia graft covering the obliterated diverticulum.