İşitmeAtölyesiAt a glance
Absence of the bony cover separating the superior canal from the skull base; an extra “third window” besides the oval and round windows forms.
Sound-/pressure-induced vertigo (Tullio), autophony (hearing one’s own voice/breathing loudly), ear fullness.
Usually not urgent; but vertigo that disrupts daily life warrants assessment.
Avoiding triggers and observation in mild cases; surgery (plugging/resurfacing the canal) in severe cases.
Medical disclaimer. This content is for informational purposes only and does not replace a physician’s examination, diagnosis or treatment; it should not be used as medical advice. For your complaints or personal situation, always consult an ear, nose and throat physician and an audiologist.
If you have vertigo triggered by loud sounds or by straining/pressure, or you hear your own voice/breathing abnormally loudly (autophony), consult an ear, nose and throat physician and an audiologist. If a “conductive loss” is reported on your hearing test while your ear is said to be intact, this picture should be investigated; a correct diagnosis prevents unnecessary ear operations.
Definition and epidemiology
Superior semicircular canal dehiscence (SSCD) is an absence of the bony cover that separates the superior semicircular canal from the skull base. This opening creates an extra “third window” besides the two windows (oval and round) normally present in the inner ear, causing sound and pressure energy to be diverted abnormally (Minor et al., 1998).
It was first described in 1998. The bone thinning is thought to become symptomatic when it weakens over a lifetime on a background of congenital predisposition; symptoms usually appear in adulthood.
Because the symptoms can affect the hearing (cochlear) and balance (vestibular) systems together, the picture is quite characteristic.
Symptoms and signs
The most striking symptom is vertigo and eye movement triggered by loud sounds (Tullio phenomenon). Straining, coughing or applying pressure to the ear can also trigger dizziness.
In the symptom called autophony, the patient hears their own voice, breathing, heartbeat and even eye movements disturbingly loudly and from inside. Ear fullness is often present.
A picture resembling a conductive loss may appear on the hearing test; but the middle ear is intact. This “pseudo-conductive loss” is important for distinguishing SSCD from conditions such as otosclerosis.
Causes and risk factors
It is basically due to the bone covering the canal being congenitally thin; head trauma, pressure changes or age-related processes can trigger this thin bone opening enough to cause symptoms.
In some people thin/open bone is found radiologically without symptoms; therefore, in diagnosis the imaging finding must be evaluated together with the clinical picture (Ward et al., 2017).
Audiological and clinical assessment
Diagnosis is made by evaluating a characteristic history, examination, audiological/vestibular tests and imaging together. Imaging alone is not sufficient.
- Pure-tone audiometry: a ‘pseudo’ conductive loss at low frequencies; but acoustic reflexes and OAE are preserved (distinguishing it from a true conductive loss).
- VEMP (cVEMP/oVEMP): an abnormally low threshold and high amplitude on the dehiscent side; among the most valuable audiovestibular findings for SSCD.
- High-resolution CT: shows the bony defect over the canal with thin slices.
- Fistula test / pressure-sound stimuli: can bring out vertigo and nystagmus.
The combination of VEMP findings with thin-slice CT is important for avoiding unnecessary surgery.
| Feature | SSCD | Otosclerosis | Tympanosclerosis |
|---|---|---|---|
| Main involvement | Superior canal (third window) | Stapes / oval window | Calcification of drum & ossicles |
| Bone conduction | Can be better than normal | Drops (Carhart notch) | Normal/drops |
| Acoustic reflex | Preserved | Lost early | May be lost |
| Autophony / Tullio | Prominent | None | None |
| Distinguishing test | VEMP + thin-slice CT | Family history, HRCT | Infection/tube history |
Treatment and audiological rehabilitation
In patients with mild symptoms, avoiding triggers and observation may be enough; not every dehiscence requires surgery.
In cases whose symptoms seriously impair quality of life, surgery (plugging/closing the canal or resurfacing) is considered. The approach and timing are individualised by an experienced team.
If hearing loss is prominent, a hearing aid; and if balance complaints persist, vestibular rehabilitation support can be provided.
Impact on quality of life and advice
Hearing one’s own voice loudly and sound-induced vertigo can make speech, social settings and working life difficult. The unusual nature of the symptoms may make the patient feel misunderstood.
Avoiding the noisy environments and sudden pressure changes that trigger symptoms, and noting the symptoms to share with the physician, are helpful. A correct diagnosis prevents unnecessary ear operations.
If you used this review, you can cite it as follows (APA 7):
İşitme Atölyesi. (2026). Superior Semicircular Canal Dehiscence (SSCD). Hearing & Balance Health Guide. https://www.isitmeatolyesi.com/en/guncel-haberler/categories/isitme-sagligi-rehberi/superior-semisirkuler-kanal-dehisansi/Permanent link: isitmeatolyesi.com/en/guncel-haberler/categories/isitme-sagligi-rehberi/superior-semisirkuler-kanal-dehisansi/ · Last reviewed: July 2026 · License: CC BY-NC-ND 4.0
References
- Minor, L. B., Solomon, D., Zinreich, J. S., & Zee, D. S. (1998). Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal. Archives of Otolaryngology-Head & Neck Surgery, 124(3), 249-258.
- Minor, L. B. (2005). Clinical manifestations of superior semicircular canal dehiscence. Laryngoscope, 115(10), 1717-1727.
- Ward, B. K., Carey, J. P., & Minor, L. B. (2017). Superior canal dehiscence syndrome: Lessons from the first 20 years. Frontiers in Neurology, 8, 177.
Frequently asked questions
Why do I hear my own voice so loudly?
This symptom is called autophony and is one of the typical findings of superior canal dehiscence. The extra opening in the inner ear makes your own voice, breathing and sometimes eye movements heard abnormally loudly from inside. Although disturbing, the underlying cause can be identified and managed.
Is dizziness with loud sound dangerous?
Although sound-induced vertigo is a disturbing symptom that makes daily life difficult, it does not itself carry a threat to life. Still, assessment is important to clarify the diagnosis and manage the triggers.
My hearing test showed a conductive loss but my ear is said to be intact; how?
Superior canal dehiscence can create a picture resembling a conductive loss on testing even though the middle ear is completely intact. Tests such as acoustic reflex and VEMP distinguish this ‘pseudo’ loss from true middle-ear problems; this distinction prevents unnecessary operations.
Do I definitely need surgery?
No. Many patients with mild symptoms can be comfortable by avoiding triggers and with observation. Surgery is considered only in selected patients whose symptoms seriously impair quality of life, and the decision is made together with an experienced team.
Scales that can be used to monitor balance complaints, daily impact and rehabilitation benefit: