Studies Examine Semicircular Canal Dehiscence, Stapedectomy Prostheses.

While the classic clinical presentation of Tullio’s phenomenon should always raise suspicion for the dehiscence syndrome, it is important to keep in mind that the presentation is not necessarily specific to the syndrome, she said.

Imaging studies show a higher prevalence of superior canal dehiscence than what has been found in autopsy series. This indicates that this condition can potentially be overdiagnosed if based on imaging alone. It is therefore crucial to correlate the radiographic impression with the clinical impression, she said.

Comparison of Stapedectomy Prostheses

When it comes to performing stapedectomy, the Nitinol prosthesis has several features that make it perform better than the more traditional Teflon-platinum prosthesis. It is not perfect, however, and there are some idiosyncracities the otolaryngologic surgeon needs to get used to.

According to Jason Diaz, MD, chief surgical resident at the University of Utah School of Medicine, the Nitinol prosthesis is superior in closing the postoperative air gap; however, the crimp doesn’t always go all the way around the stapes, and there are a few features that take getting used to. Dr. Diaz discussed the prostheses at the same COSM session, where he presented a study comparing the two devices.

To set the background, he described what an ideal stapes prosthesis would be like. The desired prosthesis…will not create an inflammatory reaction in the middle ear over time, he said. We also want a malleable device that can create a secure attachment to the incus, and does not cause necrosis over the long term. You also want to look for a device that has a similar mass to the stapes.

The Teflon-platinum prosthesis was originally introduced in 1956, and over the years has had some minor alterations in design. The platinum wire at the end is malleable, and the surgeon performs a manual crimp around the incus. The Nitinol device is 55% nickel and 45% titanium, with an offset shepherd’s crook that closes around the incus when it is heat-activated. This design avoids contact between the tip and the piston, increasing contact with the incus and avoiding an oval crimp, Dr. Diaz noted.

As for potential nickel allergy, we have not seen this to be a problem with the patients in our series, he said.

Study of Nitinol Prosthesis

Surgeons at the University of Utah started using the Nintinol prosthesis in select patients in 2004. Dr. Diaz presented details of a retrospective chart review of stapedectomies performed from 1996 to 2005. A total of 679 procedures were performed at the time, but for the study 419 were excluded, for various reasons including insufficient audiometric data, revision cases, treatment for conditions other than otosclerosis, or because prostheses other than the Teflon-platinum or Nitinol device were used.