Timothy C. Hain, MD. •Page last modified: October 11, 2020
The jugular bulb is a venous structure, that can be located close to the inner ear.The jugular bulb is not present at birth, but develops over time. The size and location is somewhat dependent on pneumatization of the mastoid bone. (Friedman et al, 2009). Other venous structures (such as the Sigmoid sinus) can also be associated with pulsatile tinnitus.
An abberent jugular bulb can cause a venous tinnitus. A high-riding jugular bulb is a common vascular anomaly, found in 2.4-7% of temporal bones. About 5 fold higher prevalence of high-jugular bulb is reported in patients with ear related symptoms -- Sayit et al reported 22% in 730 patients presenting to otolaryngology (2016).
Another variant of the high jugular bulb is a jugular bulb diverticulum - -an outpouching of the jugular bulb - -into the inner or middle ear. Most commonly the outpouching is into the middle ear. This occurs in 6% of the otherwise normal population. Sayit et al (2016) reported them in 26 of 730 patients in the otolaryngology clinic, roughly 5%.
According to Kupfer et al (2011), dehiscence in pediatric patients occurs in 8.6% of pediatric patients undergoing temporal bone CTs (one wonders why they were having temporal bone CT's). In this population, it was concluded that they were "unable to unable to identify any relationship between JBVAD and hearing loss". Of course, this leaves entirely open the question of whether jugular bulb dehiscence contributes to hearing loss in older persons as well as dizziness and tinnitus.
As noted above, there seems to be considerable differences between the prevalence of high jugular bulb in the literature, and for this reason, these statistics should considered with caution.
When present, the high jugular bulb can be associated with bleeding during surgery. When it comes into contact with inner ear structures, it can cause tinnitus, hearing loss, a conductive hyperacusis, and Meniere's disease type symptoms. Tinnitus is attributed to a direct pressure wave from the Jugular. Conductive hyperacusis can be due to increased compliance of the inner ear, in similar way as is seen in superior canal dehiscence and Fenestration surgery patients.
Meniere's disease symptoms could be due to increased compliance. Considering the high frequency of jugular bulb anomalies (about 5%), and low prevalence of Meniere's disease (about 1/2000 people, or 0.2%), it would seem possible that Meniere's disease might be caused or at least associated with by jugular bulb dehiscence or abnormalities.
Park and others (2015) have noted that there is a higher frequency of Jugular bulb abnormalities in patients with Meniere's than in controls. Park used a complex classification system to divide up their roughly 400 patients.
They identified many groups:
- High Jugular bulb (HJB) -- 13% of Meniere's group
- Jugular bulb diverticulum (JBD) -- 37.% of Meniere's
- Inner ear adjacent jugular bulb (IAJB) -- 4.6% of Meniere's
- Jugular bulb related inner ear dehiscence (JBID) -- 4% of Meniere's
- jugular bulb vestibular aqueduct dehiscence
- jugular bulb related cochlear aqueduct dehiscence
- jugular bulb related posterior semicircular canal dehiscence
They reported that the frequencies of the first 3 acronyms were higher in the Meniere's group. They proposed that "Temporal bones of MD patients might be constituted anatomically different, carrying predisposing factors for the development of clinically apparent MD."
The jugular bulb diverticulum is a much rarer anomaly than high riding jugular bulb (Stern and Goldeberg, 1980) . It can be associated with sensorineural hearing loss, tinnitus and vertigo. (Shihada et al, 2008), and may account for some cases of Meniere's disease (Yazawa et al, 1998).
Diagnosis is mainly via MRI/MRA with contrast or similar techniques that show blood flow in relation to the skull. However, MRI is not especially sensitive (Friedman et al, 2009). High-resolution CT-angiography is the method of choice, but because it is associated with some radiation, it is generally not the best choice as a screening procedure. On CT, a jugular bulb diverticulum is characterized by continuity with the jugular bulb, smooth edges, and absence of bony destruction. Some have reported that it can be diagnosed by other maneuvers, such as ultrasonography (e.g. Nakagawa et al, 2008), but we have not seen this done at any institutions that we are aware of in Chicago. VEMPs can be of low threshold on the side of the dehiscence.
Until recently, no treatment was available for tinnitus due to jugular bulb dehiscence. However, recently Dehart et al (2017) reported that "resurfacing" with hydroxyapatite cement worked in 3 patients. Yeo et al (2017) reported "resurfacing" of 2 cases of jugular bulb diverticulum with success. For both of these reports, it is difficult to imagine how this was done as these structures are encased in bone.
Abberant sigmoid sinus and stenosed dural sinuses can also cause venous tinnitus.
Orthostatic tinnitus is tinnitus that is louder in a particular body position - -upright or supine. While most tinnitus that changes with body position gets worse on standing (such as tinnitus from lowered incracranial pressure) (e.g. Arai et al, 2003), several authors have sugested that tinnitus supine might be more likely to be venous.(Bektas & Caylan, 2008; Zhang, Wang, Dai, & Chen, 2010). Orthostatic tinnitus is very rare, and at this writing (2017), we would say that this is an open issue.