CLINICAL TOPICS

Superior Canal Dehiscence

Overview

Incidence and Prevalence

Signs and Symptoms

In SCD, vestibular symptoms are the most common and also the most debilitating. However, patients can also present with auditory symptoms, with or without vestibular symptoms. The following is a list of signs and symptoms associated with SCD. Note that not all patients will experience each symptom.

Vestibular Symptoms

Common vestibular symptoms include

  • chronic unsteadiness (other symptoms are typically episodic)
  • Tullio phenomenon: vertigo and nystagmus induced by loud sounds
  • Hennebert sign: vertigo and nystagmus induced by pressure
  • oscillopsia: a visual disturbance in which objects in the visual field appear to oscillate, provoked in this case by loud sounds and/or pressure to the external auditory canal

Evoked eye movements that are seen in patients with SCD will typically be in the vertical-torsional plane either (a) torsioning away with an upward movement (this is for the vestibular ocular reflex [VOR]—slow component response—not the beat) from the affected ear in the case of positive pressure changes and resulting excitatory deflection of the cupula or (b) torsioning toward with downward movement the affected ear in the case of negative pressure changes and resulting inhibitory deflection of the cupula (Hagr, 2010). For example, right SCD will result in rightward torsion with an upbeat in response to an excitatory stimulus (sound, valsalva with closed nostrils, and positive pressure in the middle ear) or leftward torsion with a downbeat in response to an inhibitory stimulus (valsalva against closed glottis and negative pressure in the middle ear). Conversely, left SCD will result in leftward torsion with an upbeat in response to excitatory stimulus or a rightward torsion with a downbeat response due to an inhibitory stimulus (Minor, Solomon, Zinreich, & Zee, 1998).

Auditory Symptoms

Common auditory symptoms include

  • pulsatile tinnitus
  • hearing loss— most commonly low-frequency conductive or mixed (not of middle ear origin; tympanograms are normal and acoustic reflex thresholds are preserved)
  • conductive hyperacusis (increased sensitivity to bone-conducted sounds)
  • autophony (perception of one’s own body sounds at unusually high levels, such as hearing eye movements or pulse or, most commonly, one’s own voice)
  • aural fullness

Causes

Roles and Responsibilities

Assessment

Treatment

Resources

References

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