Characteristics and management of superior semicircular canal dehiscence

Abstract

Objectives To review the characteristic symptoms of superior semicircular canal dehiscence, testing and imaging of the disease, and the current treatment and surgical options. Results and Conclusions Symptoms of superior semicircular canal dehiscence (SSCD) include autophony, inner ear conductive hearing loss, Hennebert sign, and sound-induced episodic vertigo and disequilibrium (Tullio phenomenon), among others. Potential etiologies noted for canal dehiscence include possible developmental abnormalities, congenital defects, chronic otitis media with cholesteatoma, fibrous dysplasia, and high-riding jugular bulb. Computed tomography (CT), vestibular evoked myogenic potentials, Valsalva maneuvers, and certain auditory testing may prove useful in the detection and evaluation of dehiscence syndrome. Multislice temporal bone CT examinations are normally performed with fine-cut (0.5- to 0.6-mm) collimation reformatted to the plane of the superior canal such that images are parallel and orthogonal to the plane. For the successful alleviation of auditory and vestibular symptoms, a bony dehiscence can be surgically resurfaced, plugged, or capped through a middle fossa craniotomy or the transmastoid approach. SSCD should only be surgically treated in patients who exhibit clinical manifestations.

Keywords: Tullio phenomenon; autophony; hearing loss; superior semicircular canal dehiscence syndrome; vertigo.

Figure 1

Coronal view of a patient with a high-resolution computed tomography scan and an arrow pointing to the superior semicircular canal dehiscence.

Figure 2

The computed tomography scan reconstructions of a 39-year-old male patient with left-sided superior semicircular canal dehiscence who, along with experiencing other symptoms, could hear his heartbeat in the left ear and experienced oscillopsia after coughing, sneezing, or hearing loud noises in the affected ear. The scans pass through the plane of the left superior canal and are in two and three dimensions for images A and B, respectively. The white arrow indicates the dehiscence of the superior canal into the middle cranial fossa. (m, malleus head; ow, oval window; rw, round window; v, vestibule) (Reprinted with permission from Minor LB. Clinical manifestations of superior semicircular canal dehiscence. The Laryngoscope 2005;115:1717–1727.)

Figure 3

The arrow indicates the dehiscence observed in this computed tomography image from reconstructions in the plane of the left superior canal. The patient is the 39-year-old male described in Fig. 2. (Reprinted with permission from Minor LB. Clinical manifestations of superior semicircular canal dehiscence. The Laryngoscope 2005;115:1717–1727.)

Figure 4

Computed tomography scan of a superior semicircular canal dehiscence in the right ear. The axial view is displayed above the coronal view. (Reprinted with permission from Stimmer H, Hamann KF, Zeiter S, Naumann A, Rummeny EJ. Semicircular canal dehiscence in HR multislice computed tomography: distribution, frequency, and clinical relevance. Eur Arch Otorhinolaryngol 2012;269:475–480.)

Figure 5

Thresholds for vestibular-evoked myogenic potential response elicitation were recorded in 141 ears: 51 ears affected by superior semicircular canal dehiscence (SSCD), 30 normal ears in patients with SSCD in the contralateral ear, and 60 unaffected ears as controls. The boxes for these three groups represent the interquartile range, which spans from the 25^th to 75^th percentile. The whiskers represent the 10^th to 90^th percentile range, and the two lowercase Xs signify the 5^th and 95^th percentile range. The median threshold is indicated by the white circle. (Reprinted with permission from Minor LB. Clinical manifestations of superior semicircular canal dehiscence. The Laryngoscope 2005;115:1717–1727.)