Jugular bulb appearing as a mass.

A high jugular bulb might be accompanied by pulsatile tinnitus or by a vascular retrotympanic mass on otoscopic examination. Often, a high jugular bulb is difficult to differentiate from a paraganglioma [1]. The three major jugular bulb variants are an asymmetrical jugular bulb foramen, a high-riding jugular bulb with or without dehiscence, and a jugular bulb diverticulum. The size of the mass varies, depending on the size of the bony dehiscence.[2]

On coronal computed tomography, the jugular bulb will appear in direct continuity with the middle ear mass across the hypotympanic dehiscence, thereby confirming its origin (figure 1). Magnetic resonance imaging (MRI) will show the large, high-riding jugular bulb, but it is unable to demonstrate the presence or absence of dehiscent bone. In some cases, it is necessary to perform a venogram, either with a conventional digital technique or with an MRI, for confirmation (figure 2).

References

(1.) Valvassori GE, Buckingham RA. Middle ear masses mimicking glomus tumors: Radiographic and otoscopic recognition. Ann Otol Rhinol Laryngol 1974;83:606-12.

(2.) Farrel FW Jr., Hantz O. Protruding jugular bulb presenting as a middle ear mass: Case report and brief review. AJR Am J Roentgenol 1977;128:685-7.