The relationship between jugular bulb position and jugular bulb related inner ear dehiscence: a retrospective analysis.

OBJECTIVE: High jugular bulb (HJB) can erode inner ear structures creating a jugular bulb related inner ear dehiscence (JBID). The aim of this study was to analyze the relationship between the position of jugular bulb (JB) and JBID using high-resolution computed tomography (HRCT). MATERIAL AND METHODS: In this retrospective study HRCT images of 552 ears of 276 patients with hearing loss, otogenic vertigo, tinnitus or idiopathic peripheral facial nerve paralysis were analyzed. HJB type-1 was defined when JB dome reached above the inferior part of the round window, but was below the inferior edge of the internal acoustic meatus (IAM). HJB type-2 was defined when the dome of JB was higher than the inferior edge of IAM. The frequencies and types of HJB were evaluated. JBID for each HJB type was determined. Frequencies of JBID eroding the vestibular aqueduct (VA), the cochlear aqueduct and the posterior semicircular canal were examined. RESULTS: HJB type-1 and HJB type-2 were found in 19% (105/552) and in 15.8% (87/552) of studied ears. JBID showed to be in 3.8% (21/552) of all ears. 90.5% (19/21) of JBID revealed eroding of VA. Jugular bulb related cochlear aqueduct dehiscence and jugular bulb related posterior semicircular canal dehiscence were found in one ear each. The frequency of jugular bulb related vestibular aqueduct dehiscence (JBVAD) in patients with HJB reaching above IAM was higher than in patients with HJB lower than IAM. CONCLUSIONS: HJB is common, but JBID is rare. JBID prevalently erodes VA. HJB rising above IAM is most at risk to show JBVAD.