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Recurrent symptoms after stapes surgery

A 44-year-old woman who had a stapedectomy two years ago for 'otosclerosis' but whose symptoms returned and evolved.

The case

A 44-year-old florist had a left stapedectomy two years ago, performed at a different centre, for what was thought to be otosclerosis. Pre-operatively she had a left-ear low-frequency air-bone gap on audiometry and her surgeon felt confident enough in the diagnosis to proceed without further imaging.

Her hearing improved transiently after the operation but within 4 months her symptoms returned and added new dimensions. She now reports hearing her own voice booming on the left, hearing her heartbeat in the left ear, and brief vertigo when she blows her nose hard or lifts heavy boxes at work. She also has noticed that she can hear her eyes move and is unsettled by loud noises.

On examination her tympanic membranes are normal. Tuning fork testing shows Weber lateralising to the left and Rinne positive on both sides. There is no spontaneous nystagmus. Acoustic reflexes are present bilaterally — they were also documented pre-operatively. Pneumatic otoscopy on the left produces brief vertigo with downbeat-torsional eye movement.

A repeat audiogram shows persistent low-frequency air-bone gap on the left with bone-conduction thresholds of −5 dB at 500 Hz and −10 dB at 1 kHz on the left.

Question

What is the most likely explanation for the original misdiagnosis and the persistent symptoms?

Teaching point

Three audiometric findings should make a clinician question a diagnosis of otosclerosis: preserved acoustic reflexes (otosclerosis abolishes them on the affected side), supranormal bone-conduction thresholds at low frequencies (a feature of SCDS, not otosclerosis), and any sound- or pressure-induced vestibular symptoms (the third-window symptom complex). The diagnostic workup of an apparent low-frequency air-bone gap should include impedance and reflex testing, and high-resolution temporal-bone CT in Pöschl plane should be considered before any decision for stapes surgery. Stapedectomy in a patient with unrecognised SCDS may transiently improve hearing but does not address the underlying pathology and may worsen the vestibular symptoms — there are well-documented case series of patients who received stapedectomy for what was actually SCDS, with poor outcomes. SCDS plus genuine otosclerosis can rarely coexist; CT plus impedance testing distinguishes the situations.

References

  1. [1]Minor LB, Solomon D, Zinreich JS, Zee DS. Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal. Archives of Otolaryngology–Head and Neck Surgery 1998;124(3):249–258. doi:10.1001/archotol.124.3.249
  2. [2]Minor LB, Carey JP, Cremer PD, Lustig LR, Streubel SO, Ruckenstein MJ. Dehiscence of bone overlying the superior canal as a cause of apparent conductive hearing loss. Otology & Neurotology 2003;24(2):270–278. doi:10.1097/00129492-200303000-00023
  3. [3]Merchant SN, Adams JC, Nadol JB Jr. Pathophysiology of Meniere's syndrome: are symptoms caused by endolymphatic hydrops?. Otology & Neurotology 2005;26(1):74–81. doi:10.1097/00129492-200501000-00013
Related moduleSuperior Canal Dehiscence Syndrome →