Structural Causes of Intermittent Unilateral Tinnitus

Vascular Structural Abnormalities

The American College of Radiology suggests that vascular causes, such as sigmoid sinus diverticulum or dehiscence, high jugular bulb, and arteriovenous malformations, are important when tinnitus is pulsatile or changes with position/movement 1, 2
Vascular abnormalities, including sigmoid sinus diverticulum or dehiscence, can produce pulsatile tinnitus exacerbated by positional changes, as noted by the American College of Radiology 1, 2
High jugular bulb or jugular bulb dehiscence can cause audible blood flow due to vascular proximity to the inner ear structures, according to the American College of Radiology 1, 2

The American College of Radiology recommends that mass lesions in the internal auditory canal and cerebellopontine angle, such as vestibular schwannomas (acoustic neuromas), require imaging evaluation 1, 2
Vestibular schwannomas (acoustic neuromas) occur in 63-75% of patients presenting with unilateral tinnitus and are the most common retrocochlear cause, as reported by the American College of Radiology 1, 2
Meningiomas in or around the internal auditory canal and cerebellopontine angle cistern can cause unilateral tinnitus, according to the American College of Radiology 1, 2

The American College of Radiology suggests that direct examination may reveal visible structural abnormalities, such as glomus tumors (paragangliomas), which appear as retrotympanic vascular masses on otoscopy 1, 2
Cholesteatoma represents chronic inflammatory middle ear pathology requiring CT differentiation from simple otitis media, as noted by the American College of Radiology 1, 2
Otosclerosis causes conductive hearing loss with associated tinnitus through ossicular fixation, according to the American College of Radiology 2

The American College of Radiology recommends that bony abnormalities of the temporal bone, such as superior semicircular canal dehiscence, can produce sound-induced or pressure-induced tinnitus that varies with Valsalva or position changes 1, 2
Cochlear nerve aperture stenosis associated with cochlear nerve hypoplasia presents with sensorineural hearing loss and tinnitus, as reported by the American College of Radiology 1, 2

The American College of Radiology suggests that TMJ derangement or dysfunction causes unilateral tinnitus that worsens with jaw movements like yawning due to close anatomical relationship between the TMJ and ear structures 1, 2
Dedicated MRI of the temporomandibular joint should be considered when TMJ pathology is suspected based on history of jaw symptoms, according to the American College of Radiology 1, 2

The American College of Radiology recommends that MRI head and internal auditory canal without and with IV contrast is the most appropriate first-line imaging for non-pulsatile unilateral tinnitus to exclude vestibular schwannoma 1, 2
CT temporal bone without contrast plus CTA head and neck with contrast is first-line for pulsatile tinnitus to identify vascular abnormalities and bony dehiscences, as noted by the American College of Radiology 1, 2
Unilateral tinnitus has a higher risk of underlying structural pathology compared to bilateral tinnitus and should never be dismissed without imaging, according to the American College of Radiology 1, 2

The American College of Radiology suggests that intermittent symptoms should not exclude serious structural pathology—vestibular schwannomas and vascular abnormalities can produce intermittent tinnitus 1, 2
Tinnitus that changes with body position or maneuvers (like yawning) strongly suggests mechanical or vascular etiology rather than sensorineural causes, as reported by the American College of Radiology 1, 2