Department of Otorhinolaryngology - Head and Neck Surgery

An axial CT scan demonstrating a broad dehiscence of the sigmoid sinus (white arrowhead)
Figure 1. An axial CT scan demonstrating a broad dehiscence of the sigmoid sinus (white arrowhead). The patient's pulsatile tinnitus was completely eliminated subsequent to resurfacing of the sigmoid with bone cement.

Case Study from our Complex Cases Series

Michael J. Ruckenstein, MD, MSc, FACS – Vice Chairman, Penn Otorhinolaryngolgy – Professor of Otorhinolaryngology – Head and Neck Surgery

A 27 yo female presented with a three month history of unilateral pulsatile tinnitus. The patient had no hearing loss or history of ear disease as well as no complaints of neurological dysfunction. She reported that gentle compression of the left neck eliminated the sensation.

Her height was 5'0" and her BMI was 27.  We performed a physical exam including auscultation of the head and neck regions which came back normal as was her audiometric assessment. CT Angiogram of the head and neck was performed. Bone windows through the temporal bone were provided as part of this study.

The scans revealed a bony dehiscence overlying the sigmoid sinus. This was addressed with a mastoidectomy and resurfacing of the sigmoid sinus dehiscence with hydroxyapatite bone cement. In the recovery room the patient reported an immediate resolution of her pulsatile tinnitus and this resulted has persisted to date now more than one year post-surgery.

Discussion:

An axial CT venogram demonstrating a right SSD (white arrowhead).
Figure 2. An axial CT venogram demonstrating a right SSD (white arrowhead). This patient had bilateral SSDs and had bilateral repairs with resolution of her pulsatile tinnitus. She also had bilateral transverse sinus stenoses and underwent an extensive evaluation for IIH.

Up to 25% of patients with pulsatile tinnitus may result from boney anomalies of the sigmoid sinus (dehiscence or diverticula) and is likely the single most common cause. Because of this, the algorithm for diagnosing and treating patients with pulsatile tinnitus has changed significantly. Thankfully, it presents in a very consistent manner. These boney anomalies almost always affect young to middle-aged females of short stature and elevated BMIs and the tinnitus can be immediately eliminated by gentle pressure over the internal jugular vein.

For diagnosis, the initial examinations of choice are generally a CTA of the head and neck combined with bone windows of the temporal bone. In patients with conductive hearing loss on the affected side, a CT of the temporal is usually a sufficient study. If the radiologic studies are normal, then consideration can be given to send the patient to a neurovascular specialist for a formal angiogram. In bilateral cases, a MRI scan should be performed prior to angiogram to evaluate for stigmata of IIH (e.g. empty sella).

SSD is effectively treated with a cortical mastoidectomy with resurfacing of the dehiscence with an autogenous bone graft or bone cement should result in an instant alleviation of the pulsatile tinnitus with minimal risk of complications. Bone cement is preferable because of the minimal manipulation of the sigmoid sinus. It is recommended that an MRI followed by a neuro-ophthamological consultation be performed prior to surgical intervention to rule-out IIH in these patients.

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