Magnetic Resonance Angiography in Pulsatile Tinnitus: The Role of Anatomical Variations

Pulsatile tinnitus (PT) is a perception of a rhythmical sound that is synchronous with the heartbeats. Despite being seen rarely in daily practice, frequently it is associated with identifiable causes, thus warranting special attention in regard to the etiological diagnosis. PT results from blood flow turbulence, which in turn results from changes in flow velocity or in the vessel lumen. One of the most important causes of PT is the paraganglioma, a vascular tumor that appears as a reddish retrotympanic mass. However, a normal tympanic membrane mandates differentiating among other diagnoses, such as arteriovenous malformations or fistulas, intracranial or extracranial aneurysms, a high or dehiscent jugular bulb, and persistent stapedial artery. Owing to the progress of radiological evaluation, magnetic resonance angiography (MRA) has proven to be excellent for evaluating vascular diseases. From January 1995 to June 1997, the authors prospectively studied 16 patients with PT and normal otoscopic examination. The study comprised 1 male and 15 female patients (ages 25-71 years; mean age, 42.5 years). All were subjected to MRA evaluation, which revealed the etiological diagnosis in 13 cases (81.25%), including 2 aneurysms and 1 case of intracranial hypertension. Of the 13 patients 9(69.23%) presented with at least one variation of vascular anatomy of the skull, showing a close correlation, in most cases, with the side on which PT occurred. Our results confirm that MRA is an excellent primary screening modality for patients with PT and normal otoscopic findings. The authors point out the importance of making etiological diagnoses in such cases, suggesting that variations of the vascular anatomy of the skull are a possible etiology.