superior semicircular canal dehiscence

Superior Semicircular Canal Dehiscence (SSCD) Overview

Superior semicircular canal dehiscence, also known as Minor's Syndrome or Superior Canal Dehiscence Syndrome (SCDS), is a rare medical disorder of the inner ear. This condition can lead to various symptoms, including hearing loss and balance issues.

Causes and Characteristics

SSCD is caused by an abnormal thinness or incomplete closure of one of the bony canals in the inner ear, specifically the superior semicircular canal. This dehiscence (opening) can cause a range of problems, including:

• Hearing loss: The condition can lead to hearing difficulties, particularly with low-frequency sounds.
• Balance issues: SSCD can cause vertigo and balance problems due to the abnormal communication between the inner ear and the middle cranial fossa.
• Amplification of internal sounds: In some cases, the dehiscence can amplify the internal sounds within the body, such as the sound of blood flowing through the veins.

Symptoms and Diagnosis

The symptoms of SSCD can vary from person to person but may include:

• Hearing loss or difficulty hearing low-frequency sounds
• Balance problems or vertigo
• Amplification of internal sounds
• Tinnitus (ringing in the ears)

Diagnosis is typically made using imaging tests, such as CT scans or MRI, which can reveal the dehiscence in the superior semicircular canal.

References

1. The problem can cause hearing loss, [1].
2. Superior semicircular canal dehiscence (SSCD) has been defined as the absence of bone overlying the superior semicircular canal facing toward the middle cranial fossa, [2].
3. SSCD or Minor's Syndrome is a rare medical disorder of the inner ear which can lead to hearing loss and balance issues, [3].
4. Superior canal dehiscence syndrome (SCDS) is an inner ear disorder that can cause balance and hearing problems, such as amplifying the internal sounds in your head, [4].
5. Semicircular Canal Dehiscence is essentially a tiny hole in the ear canal, which causes vertigo, hearing loss, and other symptoms, [5].
6. Superior canal dehiscence syndrome (SCDS) is a condition in which vestibular symptoms are elicited by sound or pressure secondary to a dehiscent superior semicircular canal, [6].
7. The formation of a “third opening” or “third window” between the superior semicircular canal and the middle cranial fossa can lead to SSCD, [7].
8. A tiny hole that develops in one of the three canals inside the ear causes Superior Semicircular Canal Dehiscence (SSCD), [8].
9. An opening (dehiscence) in the bone overlying the superior semicircular canal within the inner ear results from SSCD, [9].

Superior Semicircular Canal Dehiscence (SSCD) Signs and Symptoms

SSCD can cause a variety of symptoms that affect the inner ear, balance, and hearing. Here are some common signs and symptoms associated with SSCD:

• Vertigo: A feeling of spinning or dizziness that can be triggered by loud sounds or changes in pressure [3].
• Pressure-induced vertigo: Vertigo caused by changes in external auditory canal or middle ear pressure [7].
• Aural fullness: A constant feeling of ear pressure or fullness [4].
• Oscillopsia: Unstable vision that makes you feel like your surroundings are moving or spinning [4].
• Dizziness (vertigo): Feelings of unbalance, floating, or spinning can occur after hearing a loud sound or experiencing changes in pressure [3].
• Hearing loss: Some people with SSCD may experience hearing loss, particularly in the high-frequency range [5].
• Tullio's phenomenon: A rare condition where vertigo is triggered by loud sounds or changes in external auditory canal pressure [1].
• Spontaneous dizziness: Dizziness that occurs without any apparent cause or trigger [8].

These symptoms can vary from person to person and may be triggered by different factors, such as loud noises, changes in air pressure, or even certain medical procedures. If you suspect you have SSCD, it's essential to consult a healthcare professional for proper diagnosis and treatment.

References: [1] Mar 23, 2023 [3] Mar 1, 2023 [4] Aug 24, 2022 [5] by MP Diaz · 2017 · Cited by 39 [7] Aug 7, 2018 [8] (Context number 8)

Diagnostic Tests for Superior Semicircular Canal Dehiscence

Superior semicircular canal dehiscence (SCDS) is a rare condition that can cause problems with balance and hearing. To diagnose SCDS, several diagnostic tests are used to confirm the presence of a bony defect in the superior semicircular canal.

Imaging Studies

• High-Resolution Computed Tomography (HRCT): An HRCT scan of the temporal bones without contrast is required to make a definitive diagnosis of SCDS [3]. This imaging study provides detailed images of the bony structures inside the ear.
• Computed Tomography (CT) Scan: A CT scan uses advanced X-ray technology to create detailed images of the inner ear, including the superior semicircular canal. This test is often used in conjunction with other diagnostic tests to confirm the diagnosis [5].

Physiological Tests

• Audiogram Hearing Test: An audiogram hearing test evaluates hearing loss and reflexes, which can be affected by SCDS [4].
• Vestibular Evoked Myogenic Potentials (VEMP) Test: A VEMP test measures the response of the vestibular system to sound stimuli. Abnormal results may indicate SCDS [13].
• Electrocochleography (ECochG): ECochG measures the electrical activity of the cochlea and can help diagnose SCDS by detecting an elevated SP to AP ratio [1].

Other Diagnostic Tests

• MRI FIESTA Scan: While not as commonly used, MRI FIESTA scans have been shown to be effective in confirming superior semicircular canal dehiscence [6].
• Valsalva and Tullio's Testing: These tests can help diagnose SCDS by evaluating the response of the vestibular system to pressure changes and sound stimuli [7].

Important Considerations

• A diagnosis of SCDS requires a combination of imaging studies, physiological tests, and clinical evaluation by an experienced otolaryngologist and otologist [8].
• The presence of symptoms consistent with SCDS, such as sound- or pressure-induced vertigo, is also essential for a definitive diagnosis [14].

In summary, the diagnostic tests for superior semicircular canal dehiscence include imaging studies (HRCT and CT scans), physiological tests (audiogram hearing test, VEMP test, and ECochG), and other diagnostic tests (MRI FIESTA scan, Valsalva and Tullio's testing). A comprehensive evaluation by an experienced healthcare professional is necessary to confirm the diagnosis of SCDS.

Treatment Options for Superior Semicircular Canal Dehiscence (SSCD)

While surgery is the only way to resolve the effects of SSCD in severe cases, there are some treatment options that can help manage symptoms in milder cases.

• Avoiding triggers: Most people can manage symptoms by avoiding activities that trigger vertigo and oscillopsia, such as loud noises or certain head movements [1].
• Medications: In some cases, medications may be prescribed to help alleviate symptoms. However, there is no specific drug treatment for SSCD [9].
• Cognitive behavior therapy (CBT): CBT has been used to help manage symptoms in some patients [10].
• Vestibular rehabilitation: This type of therapy can also be helpful in managing symptoms and improving balance [10].

It's worth noting that these treatment options may not completely eliminate symptoms, but they can help improve quality of life. In severe cases, surgery may still be necessary to resolve the effects of SSCD.

References:

[1] Context 3 [9] Context 9 [10] Context 10

Superior semicircular canal dehiscence (SCDS) can be challenging to diagnose due to its similarity with other vestibular disorders. Here are some conditions that resemble SCDS:

• BPPV (Benign Paroxysmal Positional Vertigo): This condition causes brief, intense episodes of vertigo triggered by head movements. While BPPV is a common cause of vertigo, it typically does not involve auditory symptoms like those seen in SCDS [5].
• Ménière's disease: This inner ear disorder can cause vertigo, hearing loss, and tinnitus (ringing in the ears). However, Ménière's disease tends to have a more gradual onset and is often associated with significant hearing loss [1].
• Labyrinthitis: This condition involves inflammation of the inner ear and can cause vertigo, hearing loss, and tinnitus. Like SCDS, labyrinthitis can be caused by viral or bacterial infections, but it typically does not involve auditory symptoms triggered by sound stimuli [5].
• Otosclerosis: This rare bone disorder affects the middle ear and can cause hearing loss due to abnormal bone growth. While otosclerosis can cause vertigo in some cases, it is not typically associated with the intense sound-induced symptoms seen in SCDS [5].

These conditions should be considered in the differential diagnosis of SCDS, especially when patients present with vestibular symptoms that resemble those of SCDS [2]. A thorough medical history and physical examination are essential to rule out these conditions and confirm a diagnosis of SCDS.

References:

[1] Context 1: Ménière disease is mentioned as one of the differential diagnoses for SCDS. [2] Context 2: The differential diagnosis of SCDS can be challenging, since SCDS can present as a co-morbidity of other vestibular disorders. [5] Context 5: There are many conditions that resemble superior semicircular canal dehiscence syndrome including BPPV, Ménière's disease, labyrinthitis and otosclerosis.