SPR Unknown #65 -- FINAL

Ravi Singh

Northwestern University

ravi@md.northwestern.edu

Mary Wyers

Children's Memorial Hospital

Abstract

6-year-old with vertigo induced by loud noises.

Keywords

superior semicircular canal dehiscence syndrome, CT, Tullio's phenomenon, temporal bone, 1242


Publication Date: 2006-12-06

History

6-year-old male who presents with vertigo induced by loud noises (Tullio’s phenomenon).

Findings

Image 1 – Sequential coronal CT images through the right temporal bone showing incomplete bony covering of the superior semiscircular canal and through the normal left temporal bone for comparison.

Image 2 – Sequential axial CT images through the right temporal bone showing incomplete bony covering of the superior semiscircular canal and through the normal left temporal bone for comparison.

Diagnosis

Superior semicircular canal dehiscence syndrome.

DDx

None

Discussion

Superior semicircular canal dehiscence syndrome (SSCDS) is due to incomplete bony covering of the superior semicircular canal.

Typically pressure waves enter through the oval window and exits through the round window. The bony dehiscence creates a “third window” which allows movement of endolymph, which creates a sensation of movement. Clinically, patients suffer from Tullio’s phenomenon.

Tullio’s phenomenon is vertigo and nystagmus induced by loud noises or Valsalva. The nystagmus occurs in the ipsilateral eye with inward torsion (in the plane of the superior semicircular canal). Tullio drilled holes in the semicircular canals of pigeons and observed pressure induced nystagmus in 1929.

SSCDS was originally described in 1998 by Minor after the development of high resolution CT of the temporal bones. Previously the symptoms were of unknown etiology. SSCDS is treated by plugging the bony defect with fascia via a middle cranial fossa approach.

References

  1. Belden CJ, Weg N, Minor LB, Zinreich SJ. CT evaluation of bone dehiscence of the superior semicircular canal as a cause of sound- and/or pressure-induced vertigo. Radiology 2003; 226:337–343.
  2. Minor LB, Solomon D, Zinreich JS, et al. Sound-and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal. Arch Otolaryngol Head Neck Surg 1998; 124:249–58.
  3. Minor LB. Superior canal dehiscence syndrome. Am J Otol 2000; 21:9–19.

2 images