What are the differential diagnoses for a unilaterally retracted eardrum with a pulsing sensation?

Differential Diagnoses for Unilateral Retracted Eardrum with Pulsing Sensation

A unilateral retracted eardrum with pulsatile sensation most likely represents either a vascular retrotympanic mass (paraganglioma/glomus tumor) or Eustachian tube dysfunction with coincident pulsatile tinnitus from an underlying vascular abnormality—both require urgent imaging evaluation because pulsatile tinnitus indicates structural or vascular pathology in over 70% of cases. 1, 2

Primary Vascular Causes (Most Critical to Exclude)

Paragangliomas and Glomus Tumors

• Paragangliomas (glomus tympanicum/jugulare) are the most likely diagnosis when otoscopy reveals a vascular retrotympanic mass behind a retracted tympanic membrane, accounting for 16% of pulsatile tinnitus cases and appearing as reddish, pulsatile masses on examination. 3, 1, 2
• Middle ear adenomatous tumors are rare vascular masses that show significant contrast enhancement on CT and MRI but no vascular blush on angiography, and can present with a retrotympanic mass on otoscopy. 3

Life-Threatening Vascular Abnormalities

• Dural arteriovenous fistulas account for 8% of pulsatile tinnitus cases and can lead to catastrophic hemorrhage or ischemic stroke if missed—maintain high suspicion even with isolated pulsatile symptoms. 1, 2
• Arterial dissection is potentially life-threatening and requires urgent identification, particularly if tinnitus is relieved by carotid compression. 1, 2
• Atherosclerotic carotid artery disease is the most frequent cause of pulsatile tinnitus (17.5% of cases), resulting from turbulent flow. 1

Venous and Structural Abnormalities

• Jugular bulb abnormalities (high-riding jugular bulb or dehiscent sigmoid plate) can cause pulsatile tinnitus and may be associated with tympanic membrane retraction. 1
• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension and presents with pulsatile tinnitus that may be relieved by jugular compression. 1, 2
• Idiopathic intracranial hypertension (pseudotumor cerebri) is the second most common cause of pulsatile tinnitus, particularly in young overweight women with headaches. 1
• Superior semicircular canal dehiscence allows transmission of vascular sounds and can cause pulsatile tinnitus. 1, 2

Non-Vascular Causes of Tympanic Membrane Retraction

Eustachian Tube Dysfunction

• Chronic Eustachian tube dysfunction causes negative middle ear pressure leading to tympanic membrane retraction, though this alone does not explain the pulsatile sensation. 4
• Tympanometry in ears with retracted tympanic membranes does not accurately reflect true middle ear pressure due to the air cushion trapped behind the membrane, with tympanogram peaks shifting toward negative pressures. 4

Middle Ear Pathology

• Chronic otitis media can cause tympanic membrane retraction and perforation, though the pulsatile component suggests additional vascular pathology. 5
• Cholesteatoma should be considered with chronic tympanic membrane retraction, identifiable on otoscopic examination. 3

Diagnostic Algorithm

Immediate Clinical Assessment

• Perform thorough otoscopic examination to identify vascular retrotympanic masses (reddish, pulsatile appearance suggests paraganglioma), as this fundamentally changes imaging selection. 3, 1
• Assess whether tinnitus is truly synchronous with heartbeat versus other rhythmic sounds. 2
• Test for relief with carotid or jugular compression (suggests venous etiology or arterial dissection). 1, 2
• Complete audiometric testing including pure tone audiometry, speech audiometry, and acoustic reflex testing for any unilateral tinnitus. 1

First-Line Imaging Strategy

• Order high-resolution CT temporal bone (non-contrast) as first-line when paragangliomas, glomus tumors, jugular bulb abnormalities, or superior semicircular canal dehiscence are suspected based on otoscopy. 1, 6, 2
• Order CT angiography (CTA) of head and neck with contrast as first-line when suspecting dural arteriovenous fistulas, arterial dissection, atherosclerotic carotid disease, or sigmoid sinus abnormalities. 1, 6, 2
• CTA source images can be reconstructed to create dedicated temporal bone CT images without additional radiation exposure. 1

Second-Line Imaging

• Reserve MRI with contrast and MR angiography for cerebellopontine angle lesions, vascular malformations not identified on CT/CTA, or when initial imaging is negative but clinical suspicion remains high. 1, 6, 2

Critical Pitfalls to Avoid

• Never dismiss pulsatile tinnitus as benign—identifiable causes exist in >70% of cases, and missing dural AVF can result in catastrophic hemorrhage. 1, 2
• Inadequate otoscopic examination leads to delayed diagnosis of vascular retrotympanic masses (paragangliomas), resulting in inappropriate imaging selection. 1, 2
• Do not assume tympanic membrane retraction alone explains pulsatile symptoms—the combination demands vascular imaging. 1, 2
• Overlooking intracranial hypertension in young, overweight women with headaches can lead to permanent vision loss. 1, 2
• Unilateral pulsatile tinnitus has higher likelihood of identifiable structural or vascular cause compared to bilateral presentation—always image. 1, 2