High jugular bulb: different osseous landmarks and their clinical implications

Area of Science:

• Anatomy
• Otolaryngology
• Neurosurgery

Background:

• The jugular bulb (JB) is a venous structure in the temporal bone.
• High jugular bulb (HJB) is a variation where the JB extends superiorly.
• Variations in JB anatomy can impact surgical approaches and diagnostic interpretations.

Purpose of the Study:

• To compare the incidence of high jugular bulb (HJB) relative to the internal acoustic meatus (IAM), round window (RW), and endolymphatic sac (E sac).
• To evaluate the clinical significance of HJB in relation to these anatomical landmarks.

Main Methods:

• Micro-dissection of 87 non-pathologic human temporal bones.
• Measurement of the minimum distance between the jugular fossa (JF) and the RW, IAM, and E sac.
• Classification of HJB based on specific distance criteria (≤2 mm from RW or IAM, or no distance to E sac opening).

Main Results:

• The mean minimum distance from the JF to the RW, IAM, and E sac was 2.85±1.58 mm, 3.83±2.38 mm, and 2.06±2.38 mm, respectively.
• The incidence of HJB was 32.2% relative to the RW, 24.1% relative to the IAM, and 41.4% relative to the E sac.
• Significant variability in HJB rates was observed depending on the reference landmark used.

Conclusions:

• The rate of HJB is variable and depends on the chosen anatomical landmark (RW, IAM, E sac).
• Preoperative awareness of HJB and its relationship to these landmarks is essential for procedures like cochlear implantation and vestibular schwannoma removal.
• Understanding HJB variations aids in the clinical assessment and management of conditions such as Meniere's disease.