Encountering a high jugular bulb during ear surgery

The association between high jugular bulb and mastoid pneumatization in adults

Purpose

The purpose of this study was to analyze the relationship between the degree of high jugular bulb (HJB) and mastoid pneumatization using high-resolution computed tomography (HRCT).

Methods

Between April 2019 and June 2022, HRCT of the temporal bone was retrospectively analyzed in 1,025 patients. By excluding the other coexistent pathologies, 113 patients with HJBs were recruited for the study. The degree of the HJBs were defined as follows: Grade I, JB situated between inferior annulus of tympanic membrane and cochlear basal turn (CBT). Grade II, JB situated between CBT and lateral semicircular canal (LSC). Grade III, JB situated above LSC. The volume of mastoid pneumatization was based on HRCT images using a 3D reconstruction.

Results

There were 32 male and 81 female subjects (mean age, 41.2 ± 14.0 years; age range, 18-80 years). The male group included 16 Grade I, 28 Grade II and 6 Group III HJB subjects. The female group included 38 Grade I, 62 Grade II and 31 Group III HJB cases. In the different groups of HJB, the mastoid cell volume differences were also not statistically significant (p = 0.165). In the classification, Grade II was most common (90/181, 49.7%).

Conclusion

This study found no correlation between mastoid air cell volume and HJB, suggesting that HJB may not affect the mastoid air cell development and disease occurrence. These data must be considered exploratory, requiring more extensive cross-sectional studies.

Influence of pneumatization on morphology of temporal bone-related vasculatures and their morphometric relationship with ear regions: a computed tomography study

Anatomical variations in the location and position of temporal bone-related vasculature are routinely encountered in clinical practice, contributing to clinical syndromes and complexities in ear-related and neurological surgeries. Pneumatization of the temporal bone (TB) is one of several factors that have been hypothesized to influence the variabilities and variations of these vessels. This study aimed to investigate the association between the degree of pneumatization and the morphologies of some TB-related vessels, as well as their morphometrical relationship with ear regions. Observational retrospective chart review of 496 TBs computed tomographic scans were examined. Different degrees of pneumatization were observed, with hyper-pneumatization being the most common and hypo-pneumatization being the least. Various anatomical variants of the sigmoid sinus (SS), jugular bulb (JB), and internal carotid artery (ICA) were observed. Distances of SS and JB to ear regions were observed to have significant differences (p < 0.05) in laterality. These distances increased relative to increased air cells, showing a significant association (p < 0.05). A significant association (p < 0.001) was also observed between the degree of pneumatization and variants of JB and ICA. High JB, JB dehiscence, and ICA dehiscence were significantly associated with increased pneumatization, while flat JB was significantly associated with decreasing pneumatization. However, no significant association (p = 0.070, p = 0.645) was observed between the degree of pneumatization and morphologies of SS. This study concludes that the degree of pneumatization influences only the jugular bulb variants and ICA dehiscence, as well as the distances of SS and JB to ear regions.

Prevalence of High Jugular Bulb across Different Stages of Adulthood in A Chinese Population

Pulsatile tinnitus, ear fullness, vertigo, hearing disorders, and vestibular dysfunction have been found to be related to high jugular bulb. Anatomical variation in this region also affects surgical planning and approaches. Therefore, knowledge on the detailed anatomy of the high jugular bulb is critical for middle ear and lateral skull base surgery. Prevalence of high jugular bulb is uncertain as data are usually derived from temporal bone specimens and patient reports from hospitals. Therefore, a community-based epidemiological study is necessary to understand the significance of high jugular bulb anatomy. Here, we report a cross-sectional study to characterize the prevalence of high jugular bulb and jugular bulb size using a 3.0 T magnetic resonance imaging. Furthermore, we studied the relationship between the prevalence of high jugular bulb and age-related changes. We enrolled 4539 permanent residents (9078 ears) from two communities in the Shanghai region who underwent magnetic resonance imaging between 2007 and 2011. We divided participants into four subgroups according to age: 35-44 (early middle age), 45-54 (middle age), 55-64 (late middle age), and 65-75 (late adulthood) years. We found that the overall prevalence of high jugular bulb was 14.5% in a Chinese population. There was a higher prevalence of high jugular bulb on the right side and especially in women (both p < 0.001). The occurrence of high jugular bulb was higher in the early middle age group and gradually decreased with age, but was still present in the late adulthood group (p = 0.039). These findings provide useful information on the prevalence of high jugular bulb in a Chinese population and the distribution in age groups, suggesting that high jugular bulb should be considered, even in those without ear disorders. This work serves as a foundation for further research on the relationship between jugular bulb changes and disease symptoms.

Jugular bulb and skull base pathologies: proposal for a novel classification system for jugular bulb positions and microsurgical implications

OBJECTIVE

There is no definitive or consensus classification system for the jugular bulb position that can be uniformly communicated between a radiologist, neurootologist, and neurosurgeon. A high-riding jugular bulb (HRJB) has been variably defined as a jugular bulb that rises to or above the level of the basal turn of the cochlea, within 2 mm of the internal auditory canal (IAC), or to the level of the superior tympanic annulus. Overall, there is a seeming lack of consensus, especially when MRI and/or CT are used for jugular bulb evaluation without a dedicated imaging study of the venous anatomy such as digital subtraction angiography or CT or MR venography.

METHODS

A PubMed analysis of “jugular bulb” comprised of 1264 relevant articles were selected and analyzed specifically for an HRJB. A novel classification system based on preliminary skull base imaging using CT is proposed by the authors for conveying the anatomical location of the jugular bulb. This new classification includes the following types: type 1, no bulb; type 2, below the inferior margin of the posterior semicircular canal (SCC), subclassified as type 2a (without dehiscence into the middle ear) or type 2b (with dehiscence into the middle ear); type 3, between the inferior margin of the posterior SCC and the inferior margin of the IAC, subclassified as type 3a (without dehiscence into the middle ear) and type 3b (with dehiscence into the middle ear); type 4, above the inferior margin of the IAC, subclassified as type 4a (without dehiscence into the IAC) and type 4b (with dehiscence into the IAC); and type 5, combination of dehiscences. Appropriate CT and MR images of the skull base were selected to validate the criteria and further demonstrated using 3D reconstruction of DICOM files. The microsurgical significance of the proposed classification is evaluated with reference to specific skull base/posterior fossa pathologies.

RESULTS

The authors validated the role of a novel classification of jugular bulb location that can help effective communication between providers treating skull base lesions. Effective utilization of the above grading system can help plan surgical procedures and anticipate complications.

CONCLUSIONS

The authors have proposed a novel anatomical/radiological classification system for jugular bulb location with respect to surgical implications. This classification can help surgeons in complication avoidance and management when addressing HRJBs.