Semicircular Canal Dehiscence

Superior Semicircular Canal Dehiscence (SSCD) is the result of a hole in the bony portion of your vestibular system. Your inner ear system is deep inside your ear and consists of two parts. The first is your cochlea, your hearing organ. And the second is your vestibular system, which consists of three semicircular canals, the utricle, and the saccule; you can find them pictured here. These canals detect angular motion and help with spatial awareness; this is how we know where our head is in space. If you have SSCD, you may have a thinner wall on your superior semicircular canal, or even a hole. This hole or thinned wall causes vestibular symptoms due to pressure fluctuations and/or changes in loud sounds. 

There are supposed to be two holes in your inner ear, the oval window (for sound transmission), and the round window (where sound exits) (1). These two windows allow pressure fluctuations and sounds to transmit functionally through our vestibular system (1). However, the addition of a third hole, a dehiscence, allows for improper signals to be sent and causes your dizziness symptoms. It is unlikely there there is anything you did to make this happen – research shows that Semicircular Canal Dehiscence is usually caused by a developmental abnormality. If you have an already thinned superior canal bone, head trauma or pressure caused by the temporal lobe of your brain can cause it to wear down, which forms the dehiscence. The dehiscence causes uncomfortable symptoms that can be either intermittent or chronic.

Symptoms & Diagnosis

Symptoms of Superior Semicircular Canal Dehiscence can vary from hearing to imbalance issues. Because there is a hole in the system, many people present with different symptoms. These symptoms include, but are not limited to: (1, 2, 3)

  • Vertigo
  • Non-vertiginous dizziness (lightheadedness, feeling like your brain is spinning)
  • Nystagmus (involuntary eye movement) in response to loud sounds or pressure changes
  • Unsteadiness and disequilibrium (feeling as though you may fall)
  • Oscillopsia (the sensation that the world is moving around you)
  • Aural fullness
  • Coughing, straining, sneezing cause dizziness or lightheadedness
  • Hearing yourself speak more loudly in one ear than the other
  • Hearing your own heartbeat, blood flow, or eye muscles move
  • Migraines

Many of these symptoms of spontaneous vertigo and lightheadedness have similar symptoms to other vestibular diagnoses such as:

To diagnose your symptoms, there are a few tests that your healthcare team will likely recommend. These diagnostic tests will begin with a thorough history of your symptoms to rule out other vestibular diagnostic possibilities. Then, if SCD is predicted you will be placed through one or more of the following tests:

  • VEMP
  • CT scan
  • Audiogram
  • VNG

Once you receive a diagnosis, your providers will devise a treatment plan that suits your specific needs.

Treatment

Most patients with Superior Semicircular Canal Dehiscence can manage their symptoms by avoiding stimuli like sudden loud noises. However, for those who cannot manage their symptoms with avoidance, there are other treatment options. These options are tinnitus retraining therapy, using a hearing aid, treating migraines if you have them, and surgical correction (2). If your symptoms are mild and not debilitating, the surgical option is not recommended as the risks often outweigh the benefits. 

Surgical correction is for those deeply affected by SSCD. The hole in the canal is plugged with fascia, which is thick connective tissue, to eliminate fluid movement (3). There are many risks to this procedure such as hearing loss, BPPV, high frequency sensorineural hearing loss, and general vestibular dysfunction. Luckily, most people who undergo this procedure have positive results. 

If you have any remaining symptoms from the surgery of imbalance, vestibular migraine, or other general vestibular dysfunction, physical therapy can help. 

Physical Therapy

Physical therapy for Superior Semicircular Canal Dehiscence will be treating the symptoms that affect you. Your physical therapist can help you with improving your balance, improving your lightheadedness or dizziness symptoms, and assisting with vestibular migraine. Vestibular Rehabilitation Therapy, or VRT, is very effective in improving vestibular dysfunction. Your PT will be able to find what stimuli are increasing your symptoms and slowly help your brain adapt to the stimuli in a more normal way. Having a PT as a part of your healthcare team will be vital to your recovery and management for SSCD. VRT will help you with imbalance, dizziness, and vertigo symptoms. 

Sources:

(1) Minor, L. (2020, June 26). Superior Semicircular Canal Dehiscence (SSCD). Retrieved September 10, 2020, from https://vestibular.org/article/diagnosis-treatment/types-of-vestibular-disorders/superior-semicircular-canal-dehiscence-sscd/

(2) BC Balance and Dizziness. (2019, September). Semicircular Canal Dehiscence. Retrieved September 10, 2020, from https://balanceanddizziness.org/disorders/vestibular-disorders/semicircular-canal-dehiscence/

(3) Carey, J. (n.d.). Superior Canal Dehiscence Syndrome (SCDS). Retrieved September 10, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/superior-canal-dehiscence-syndrome-scds

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