What is the differential diagnosis (ddx) for an adult patient with no significant past medical history experiencing tinnitus that wakes them from sleep?

Differential Diagnosis for Tinnitus That Wakes Patient from Sleep

Tinnitus that wakes a patient from sleep is highly unusual and should immediately raise suspicion for objective tinnitus with a vascular or neuromuscular etiology, particularly pulsatile tinnitus from vascular abnormalities or typewriter tinnitus from neurovascular compression of the cochlear nerve. 1, 2

Critical Distinguishing Feature: Sleep Disruption

The fact that tinnitus wakes the patient from sleep is a red flag that distinguishes this from typical subjective tinnitus, which comprises 70-80% of cases and rarely disrupts sleep to this degree 3. This presentation demands evaluation for objective causes that can be detected on examination 1.

Primary Differential Diagnoses

Pulsatile Tinnitus (Vascular Etiologies)

This is the most likely category when tinnitus is severe enough to wake someone from sleep. 1

Vascular causes to consider include:

• Arteriovenous malformations or dural arteriovenous fistulas - these create audible vascular flow that can be loud enough to disrupt sleep 3
• Carotid cavernous sinus fistulas - produce rhythmic pulsatile sounds 3
• Paragangliomas (glomus tumors) - vascular middle ear tumors that create objective pulsatile tinnitus 3
• Arterial dissection or fibromuscular dysplasia of carotids - can produce audible turbulent flow 3
• Transverse sinus stenosis or sigmoid sinus diverticulum - venous causes of pulsatile tinnitus 3
• Prominent mastoid or condylar emissary veins - can create audible venous hum 3

Typewriter Tinnitus (Neurovascular Compression)

This is a critical diagnosis not to miss, as it responds remarkably well to carbamazepine. 2

• Presents with paroxysmal attacks of staccato, clicking sounds caused by neurovascular compression of the cochlear nerve 2
• The pattern is episodic and paroxysmal, not continuous, which could explain why it wakes the patient during acute episodes 2
• Requires MRI with heavily T2-weighted thin-section sequences to detect neurovascular loops in contact with cranial nerve VIII 2

Palatal or Tympanic Myoclonus

This represents pulse-asynchronous objective tinnitus from muscle contractions. 1

• Creates clicking sounds from rhythmic muscle contractions in the middle ear or palate 1
• Can be loud enough to be audible to the examiner and potentially disrupt sleep 1

Secondary Considerations

Intracranial Hypertension

• Can cause pulsatile tinnitus that may be positionally worse and potentially disruptive at night 3
• Often associated with other neurologic symptoms 3

Superior Semicircular Canal Dehiscence

• Bony abnormality that can cause autophony and perception of internal body sounds amplified 3
• Patients may hear their own eye movements or heartbeat loudly 3

Critical Clinical Approach

First, determine if the tinnitus is pulsatile or non-pulsatile, as this fundamentally changes the diagnostic workup. 1

Key History Elements to Elicit:

• Quality of sound: clicking/staccato (typewriter tinnitus), whooshing/rhythmic (vascular), or other 1, 2
• Synchronization with heartbeat: pulse-synchronous suggests vascular etiology 1
• Laterality: unilateral tinnitus warrants more aggressive workup 4
• Associated symptoms: hearing loss, vertigo, neurologic deficits 1
• Positional variation: worse when lying down suggests venous etiology 3

Physical Examination Priorities:

• Auscultation over the neck, periauricular area, and mastoid to detect objective tinnitus 1
• Otoscopic examination to identify retrotympanic masses or vascular abnormalities 1
• Neurologic examination to detect focal deficits 1

Imaging Recommendations:

Imaging is strongly indicated for this presentation, contrary to typical tinnitus. 1

• MRI with heavily T2-weighted sequences is appropriate for suspected typewriter tinnitus or to evaluate for neurovascular compression 2
• CT angiography or MR angiography/venography for suspected vascular causes of pulsatile tinnitus 1
• The AAO-HNS makes a strong recommendation against imaging for bilateral, non-pulsatile tinnitus without neurologic abnormalities or asymmetric hearing loss, but this patient's presentation does not fit that low-risk profile 1, 4

Common Pitfalls to Avoid

• Do not dismiss this as typical subjective tinnitus - the sleep disruption indicates a more severe or objective process 1
• Do not delay audiologic evaluation - comprehensive audiometry should be obtained promptly for persistent or unilateral tinnitus 4
• Screen for severe anxiety or depression - patients with bothersome tinnitus have documented increased suicide risk and require prompt mental health intervention 3, 4
• Consider trial of carbamazepine if typewriter tinnitus is suspected based on clicking/staccato quality, as response can be diagnostic and therapeutic 2