The apex of the jugular bulb was 3 mm higher than the floor of the internal auditory canal. Methods: Two hundred temporal bone CT scans were evaluated for the prevalence of dehiscence between the jugular bulb and vestibular aqueduct. Turbulent or slow flow in a high or protruding jugular bulb can result in loss of the flow void and contrast enhancement at magnetic resonance (MR) imaging, thereby mimicking real disease. It has been shown that the right-sided jugular bulb in two-thirds of the population is larger compared to the left side. High-resolution CT scans of 408 temporal bones obtained from 208 adults were recruited. - The superior border of the jugular bulb normally lies below the hypotympanum of the middle-ear cavity. Methods: Two hundred temporal bone CT scans were evaluated for the prevalence of dehiscence between the jugular bulb and vestibular aqueduct. Due to their highly vascular nature, these tumors take up contrast intensely on MRI and appear white on post-contrast images. Objective: To determine the incidence of dehiscence between the vestibular aqueduct and the jugular bulb on computed tomography (CT) scans and assess its implication as a cause of dizziness or hearing loss. High-resolution computed tomography (HRCT) and three-dimensional reconstruction (3DRC) were used to detect the anatomical variables associated with VA and jugular bulb (JB) in hydropic and non-hydropic ears. Radiographic features. Several microanatomic studies showed, however, that this conventional compartmentalization of the jugular foramen might be an oversimplification that lacked surgical significance. This anomaly is known as a high-riding jugular bulb. This article presents an overview of the anatomy of the jugular foramen with its variants and anomalies, and illustrates the pathologic processes that may involve the foramen. Jugular bulb diverticulum was once thought to be rare, with only a limited number of reported cases in the English literature. The jugular bulb is often asymmetric, with the right jugular bulb usually being larger than the left. 6 ). Listing a study does not mean it has been evaluated by the U.S. Federal Government. The height of the jugular bulb was measured from the lower margin of the tympanic annulus to the apex of the jugular bulb by counting CT slices individually on the both side. Results: High jugular bulbs were noted in 8.2% (130/1579) of temporal bone specimens and in 8.5% (17/200) of temporal bone CT. Images produced by the CT scan highlighting bone details are most useful for assessing and diagnosing conditions. The depiction of dehiscent jugular bulb-vestibular aqueduct should be considered with caution as the sole cause of symptoms. More importantly, it is imperative that surgeons are alerted to this anatomic variant, in view of the high risk of torrential bleeding should a myringotomy or exploratory tympanotomy be performed in these patients. This imaging method can visualize the temporal bone’s small and fine structures to the maximal detail. At the time of initial examination of the ear, the two may be indistinguishable. A high-riding jugular bulb has been reported in up to 15% of the population, with dehiscence in as many 2% of high-riding jugular bulbs. Some have reported that it can be diagnosed by other maneuvers, such as ultrasonography (e.g. Correlation of the imaging findings and clinical data was performed. Some have reported that it can be diagnosed by other maneuvers, such as ultrasonography (e.g. It drains extracranially to the internal jugular vein as it passes through the jugular foramen of the posterior cranial fossa. Tertiary academic medical center. Nakagawa et al, 2008), but we have not seen this done at any institutions that we are aware of in Chicago. Although repeated CT scan failed to detect abnormal findings in both the supra- and infra-tentorial regions, MRI clearly visualized a thrombus which was situated within the right jugular bulb. The right jugular bulb is larger than the left in 75% of individuals. The jugular bulb is often asymmetric, with the right jugular bulb usually being larger than the left. The IXth nerve has two ganglia within the foramen. To determine the prevalence of jugular bulb and vestibular aqueduct dehiscence (JBVAD) in pediatric patients undergoing temporal bone computed tomography (CT) scans and to assess the relationship between JBVAD and hearing loss. Carotid canal integrity, jugular bulb position, petrous apex pneumatization and the minimal thickness of the carotid canal wall (TCW) facing the tympanic cavity were examined and measured for … The tumour was removed via a suboccipital retrosigmoid approach. Figure 3 MRI T1 axial scan (equivalent plain): contrast-enhanced, HJB (B) protruding into tympanic cavity, mastoid segment of facial nerve (N VII). floor of the internal acoustic meatus (internal auditory canal) 2,4; 2 mm below the floor of the internal acoustic meatus 3 In this case, the sigmoid plate which is normally present between a high riding jugular bulb and middle ear cavity, is absent which defines this as a focal dihiscence. In addition to its intrinsic pathologic conditions, a variety of lesions can arise from the contiguous surrounding structures and invade the foramen. This imaging method can visualize the temporal bone’s small and fine structures to the maximal detail. Followup CT skull base did demonstrate abnormality of the left jugular bulb with deficiency of the left sigmoid plate (image 4, red arrow) with communication between the jugular bulb … Asymmetrical large jugular bulb: It is a normal variation and usually asymptomatic. Most of these patients are asymptomatic, although some may complain of low rumble pulsatile tinnitus or conductive hearing loss secondary to obliteration of the round window niche or impingement of the ossicular chain. If it reaches above the posterior semicircular canal it is called a high jugular bulb. - A high-riding jugular bulb has an intact sigmoid plate - a thin plate of bone separating the jugular bulb from the middle-ear cavity.. Study Design. The sigmoid (jugular) plate normally separates the jugular bulb, whether high riding or not, from the hypotympanum of middle ear cavity. 8.1c) of the same patient re-illustrates the findings.The left-sided internal jugular vein and jugular bulb are hypoplastic. High-resolution computed tomography (HRCT) and three-dimensional reconstruction (3DRC) were used to detect the anatomical variables associated with VA and jugular bulb (JB) in hydropic and non-hydropic ears. After entering the jugular foramen, the IXth nerve turns and forms a genu, which is lodged near the external opening of the cochlear aqueduct, before coursing inferiorly into the carotid space. The associated enlargement of the jugular foramen can simulate a mass lesion on non-contrast-enhanced CT, although the diagnosis is made easily on contrast-enhanced CT or flow-sensitive MR imaging. The posterior meningeal artery, usually a branch of the ascending pharyngeal artery, ascends through the jugular foramen adjacent to the Xth and XIth nerves to supply the posterior fossa meninges. Video 4. Jugular bulb dehiscence repair. 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