Canal Dehiscence

Procedures & Operations

What is Canal Dehiscence

Superior canal dehiscence syndrome (SCDS) is a rare medical condition of the inner ear, leading to hearing and balance disorders in those affected. The symptoms are caused by a thinning or complete absence of the part of the temporal bone overlying the superior semicircular canal of the vestibular system. This may result from slow erosion of the bone or physical trauma to the skull and there is evidence that the defect or susceptibility is congenital.

The Surgery Explained

Two surgical approaches have been used – superior canal resurfacing and superior canal plugging. Although theoretically less traumatic to the membraneous labyrinth, resurfacing techniques have led to recurrent symptoms secondary to shifting or resorption of the bone and fascia reconstruction. Plugging with bone wax, bone paste, or fascia has been more commonly used to create a stable seal of the dehiscent superior semicircular canal.

Middle fossa craniotomy is a safe surgical procedure and is the most common approach used to repair SCD. In many cases, the skull base, or tegmen, is low-lying, and will have multiple holes or defects that in some cases allows for brain to herniate into the ear / mastoid / middle ear. The craniotomy approach is ideal to:

  • visual the SCD directly;  and
  • repair the tegmen defect(s) directly using bone and fascia.

If the skull base or tegmen is very low it can be difficult to safely reach the superior canal safely with a transmastoid approach to create two labyrinthotomies (as the SCD is not directly repaired) and then plug these two holes to indirectly repair the defect.

Ideally, the transmastoid approach may be useful for a patient that has SCD and a skull base or tegmen that is NOT low-lying and has no other associated holes or brain herniating into the ear. In some cases, the SCD may be located along the SIDE of the canal and not on the TOP, as seen in most classic cases of SCDS. If the defect is located on the side of the canal away from the surgeon (posterior-medial), the SCD may be more difficult to visualize using a craniotomy approach.

The transmastoid approach is a safe approach and small studies have shown that this is a reasonable alternative surgical technique for SCDS, provided that the skull base / tegmen is not too low and that there is no evidence for large defects / holes in the skull base or brain sagging into the ear.

What to Expect Following Your Surgery

You will be given post-operative instructions along the following guidelines:

  1. Adults: No heavy lifting or strenuous activity for 1 week and no contact sports for 4 weeks following the surgery.
    Children and Infants: No heavy lifting, strenuous activity, contact sports, or gym classes for 4 weeks following the surgery.
  2. Head should be elevated on 1-2 pillows when lying down for 1 week following surgery.
  3. Remove the entire ear bandage 5 days after the surgery (unless it has already been removed during your hospital stay).   The sutures will dissolve on their own.  Oozing is normal and will decrease with time.
  4. Showering and bathing is allowed when you return home.  You may wash your hair after the bandage has been removed.
  5. Clean the incision with half-strength hydrogen peroxide (1/2 water, 1/2 hydrogen peroxide) to remove any old blood clots or crusting on the wound with Q-tips. DO NOT replace the bandage, leave the incision open to air.  If there is any oozing, you may use a small sterile adhesive bandage temporarily.
  6. Apply Vaseline to the incision after cleansing with hydrogen peroxide. Do not use Neosporin or Bacitracin as a growing number of patients are developing allergies to these ointments.
  7. Keep your operated ear dry with an ear plug or a cotton wool ball and Vaseline – if there is excessive drainage from the ear you may leave the cotton wool ball in the ear.
  8. You will be given an antibiotic to take by mouth following surgery. Please ensure the medication is finished as prescribed; do not stop early even if you feel well. If you think that you may be developing an allergic reaction to the antibiotic, a yeast infection, excessive diarrhoea or loose stools, or have severe abdominal cramping, please call your doctor’s office. Contact us as soon as possible for any high fevers, severe headaches, or unusual neck stiffness.
  9. The first post-operative clinic visit is 1 week after the surgery.

Following your operation, you may suffer from:

Pain: You will be given a pain medication to be taken for the first several days after surgery.  Pain is not unusual during the first two to four weeks after surgery and will slowly improve in most cases.

Pain above or in front of the ear is common when chewing and is temporary. As one of your major chewing muscles (temporalis muscle) is stretched during surgery it will take time to heal. Avoid chewy or hard foods for about 4 weeks after surgery until the discomfort begins to improve.

Swelling: Swelling is expected following surgery. The swelling can occur behind the ear, in the region of the scalp where the hair was shaved, in front of the ear, around the eye, or around the mouth. Some bruising may also occur. The ear may appear to stick out or appear to be higher or lower than the other ear. This is normal and will gradually improve over the weeks following surgery.

Drainage or discharge: A bloody or watery discharge is expected during the healing process. Call your doctor’s office should a yellow or green discharge with a foul odour occur. Some patients notice a nosebleed or spit up blood – this is common and results from the blood that accumulates in the middle ear during surgery, and drains into the back of the nose. This is not a cause for concern.

Ear numbness: Your ear may feel numb – this is temporary and will improve over several weeks or months. Be careful when using a hair dryer on a hot setting to avoid injury to the skin until sensation returns.

Ear fullness or popping: You may experience fullness of the ear or hear popping, crackling, or other sounds in the ear. This is usually temporary and is often due to the blood, fluid and dissolvable packing in the ear canal and middle ear (behind the eardrum).

Ringing (Tinnitus): Patients may notice ringing or buzzing of the ear after surgery –this is often temporary or decreases with time.

Dizziness: Dizziness may occur following surgery. Avoid sudden movements; stand up slowly. Dizziness is usually temporary and will improve with time. Gradually increase your activity levels.

Bruising around the eye or corner of the mouth: Your may have some slight bruising around the eye or corner of the mouth – this occasionally occurs because of the facial nerve monitor electrodes and is temporary.