Dehiscent jugular bulb, CT, Otoscopy, Pulsatile mass
A 41-year-old female patient with 2-year history of tinnitus in right ear admitted to our clinic. The patient underwent temporal bone CT imaging. CT demonstrated right dehiscent high riding jugular bulb with absence of the right sigmoid plate (Figure 1).
A dehiscent jugular bulb is deﬁned as a normal venous variant with superior and lateral extension of the jugular bulb into the middle-ear cavity through a dehiscent sigmoid plate . Despite its rare frequency, dehiscent jugular bulb is one of the common cause of pulsatile tinnitus. In a study, high resolution CT scans of 700 temporal bones of 350 patients were retrospectively examined for the incidence of vascular variations showed that dehiscent jugular bulb was seen in 27 (3.9%) temporal bones . Patients with dehiscent jugular bulb can be completely asymptomatic or may suffer from dizziness, pulsatile tinnitus and hear loss . Otoscopy may show a bluish, pulsatile mass. CT has a major role in outlining the defect of sigmoid plate . During the middle ear surgery jugular bulb may injure; consequently, it is important to warn surgeons about this pitfall before the operation.
Figure 1: CT demonstrates right dehiscent high riding jugular bulb with absence of the right sigmoid plate (arrow).