FRCS (ORL-HNS) · SECTION 1 SBA

Third-window syndrome versus otosclerosis

A patient has autophony, pressure-induced vertigo, a low-frequency air–bone gap and preserved acoustic reflexes. CT appears to show superior canal dehiscence. Which additional finding most strengthens the diagnosis before offering surgery?

CHOOSE ONE ANSWER

Best of five

  1. A. Absent stapedial reflexes
  2. B. Physiological evidence of a third-window mechanism, interpreted with symptoms and correctly reformatted imaging
  3. C. A normal vestibular history
  4. D. Exploratory stapedotomy
  5. E. A single axial CT slice
ANSWER AND REASONING

B. Physiological evidence of a third-window mechanism, interpreted with symptoms and correctly reformatted imaging

CT alone can overcall dehiscence. Concordant symptoms and physiological testing distinguish a true third-window syndrome from incidental thin bone or middle-ear conductive disease.

Why every option is right or wrong

A. Absent stapedial reflexes: This would favour stapes fixation rather than a third-window pattern.

B. Physiological evidence of a third-window mechanism, interpreted with symptoms and correctly reformatted imaging: CT alone can overcall dehiscence. Concordant symptoms and physiological testing distinguish a true third-window syndrome from incidental thin bone or middle-ear conductive disease.

C. A normal vestibular history: This weakens the clinical case for symptomatic dehiscence.

D. Exploratory stapedotomy: This risks treating an apparent conductive gap with the wrong operation.

E. A single axial CT slice: Inadequate plane and slice thickness can mislead.

What if the scenario changed?

If acoustic reflexes were absent and there were no sound/pressure symptoms, otosclerosis would become more likely.