Prevalence of Jugular Bulb Abnormalities and Resultant Inner Ear Dehiscence: a Histopathologic and Radiologic Study

Abstract

Objective: Jugular bulb (JB) abnormalities including high riding JB and JB diverticulum can erode inner ear structures and cause hearing loss, dizziness, and tinnitus. This study investigates 1) the prevalence of JB abnormalities, and 2) their erosion into inner ear structures using temporal bone histopathology and computed tomography (CT). Method: A total of 1579 temporal bones and 100 CT of the temporal bones (200 ears) were reviewed. The presence of a high JB was recorded as was its erosion into inner ear structures. Accompanying demographic and clinical information was reviewed. Results: High JB was noted in 8.2% (130/1579) of temporal bone specimens, and in 8.5% (17/200) of cases radiologically. Histologically, high JB were more common on the left side, in women, and in those greater than 40 years old. There was no significant increase in the prevalence of high JB over age 40 years. High JB eroded inner ear structures in 34% (44/130) of cases histologically and 18% (3/17) radiologically. The vestibular aqueduct was most frequently dehiscent histologically (n = 41) and radiologically (n = 3). Posterior semicircular canal and facial nerve were infrequently dehiscent. Only 2 out of 41 histological cases of vestibular aqueduct dehiscence had hydrops or a clinical history of Ménière’s disease. Conclusion: JB abnormalities are common. They are present in 8% to 9% of individuals and are acquired by age 40 years. In 1/3 of cases, high riding JB erodes the inner ear, most frequently involving the vestibular aqueduct. Contrary to expectation, dehiscence of the vestibular aqueduct is infrequently associated with endolymphatic hydrops clinically or histologically.