Using Materialise Mimics Software to Predict Thyroplasty Success in Trans Women

While a trans person should not be expected or feel pressured to be surgically altered in order to have their gender identity respected, many trans people do elect to have some type of surgery to help them conform to generally accepted gender norms. In a perfect world, there would be no pressure placed on trans people to undergo alteration of any kind in order to have their gender accepted, but sadly many still feel the pressure and many even want to have their bodies more closely align with their gender. While trans people commonly take hormone supplements, there are several surgical options that are relatively common. Trans men often have their breast tissue removed, while trans women can have breast implants or even slight facial reconstruction to soften their jawlines.

While sexual reassignment surgeries have come a very long way since they were first performed by Dr. Magnus Hirschfeld in the 1930s, there are some traits that aren’t always able to be altered. One of the defining characteristics often used to identify a woman is her voice, and while hormones and speech therapy may be successful in helping trans women soften and raise the pitch of their voice, it isn’t always possible. The next step is consulting a laryngologist, and the patient can undergo a phonosurgery called cricoid-thyroid approximation (CTA) that can alter the voice.

The CTA procedure involves attaching the cricoid cartilage to the thyroid cartilage, which increases the length and tension of the vocal cord. This can often result in a higher, and more generally accepted feminine, voice. Unfortunately, CTA doesn’t work for about a third of the patients who undergo it, and until now no one really knew why. Otolaryngology specialist Dr. Claudio Storck from the University Hospital of Basel, Switzerland wanted to find out why it didn’t work, and see if he could find a way to make the procedure more effective for a greater number of his patients.

While there have been previous studies performed on the crico-thyroid joints (CTJ) that show that humans typically have one of three different types (defined as type A, type B and type C), there was no data on how the three different CTJs would respond to the CTA procedure. Using Materialise Mimics software, Dr. Storck and his team of researchers examined the original CT scans of trans patients’ pre-operative crico-thyroid joints. The software allowed them to generate high-resolution 3D images of the patients’ larynx, which could be more closely examined than 2D images. The three types of CTJs were immediately identifiable to the team, so Storck compared them to the final results of the surgery to see if the success and failure rate was associated.

It became obvious immediately that the success of the surgery was directly related to the type of CTJ the women had. Ten of the eleven women patients who had the type A CTJ resulted in a satisfactory alteration of their voice. However, none of the women who had type B or C ended up with a satisfactory outcome, and their voices remained unchanged. Dr. Storck concluded that using 3D images of the patients CTJ to determine what type they have was a vital step that should be taken before the procedure is performed. He now uses this 3D imaging process as a deciding factor in determining who should and should not be considered for a CTA.

“Three-dimensional images allow the differentiation of type A versus type B/C CTJs but not the distinction between type B and type C CTJs. Both vocal pitch elevation and vocal fold elongation following CTA are significantly greater in patients with type A CTJs than in patients with type B/C CTJs. Based on these preliminary results, we recommend identifying the CTJ type on 3-D images and limiting CTA to patients with type A CTJs,” the conclusion for the research notes.

Sadly Dr. Storck’s research, which earned him the first prize in the Europe and Africa category of the Mimics Innovation Awards in 2015, doesn’t help any trans women with a type B or C CTJ obtain their desired voice. But it will prevent them from undergoing an unnecessary surgery, and spare them from the emotional frustration of dealing with the painful recovery process only to see unsatisfactory results. However, now that medical science knows why the CTA is only successful on certain patients, there is hope that it could eventually lead to a procedure that will work regardless of the anatomy of the patient’s throat. Discuss in the 3D Imaging of Larynx forum over at 3DPB.com.