Spiral CT could prove to be the definitive tool for assessing laryngeal framework surgery pre- and post-operatively, according to a team of German radiologists and otolaryngologists.
The group, from Martin Luther University in the cities of Halle and Salle, retrospectively studied the records of 29 transsexual patients who had undergone cricothyroid approximation surgery to raise their vocal pitch. CT exams were done to guide the procedure and to determine the aftereffects of the surgery.
"Sexual reassignment surgery for individuals with gender identity confusion has been successful, especially in the male-to-female transformation. A troublesome problem for these individuals is retention of their male voice. Cricothyroid approximation raises the vocal pitch by simulating the contraction of the cricothyroid muscles with sutures," the group wrote in the British Journal of Radiology (August 2000, Vol.73:872, pp.840-843).
But current laryngoplastic surgical techniques do pose some complications, such as cartilage erosion and high vascularization at the suture site. In addition, there is no reliable way to evaluate the cricothyroid after surgery to determine how successful the procedure was.
The CT scans were performed with a Somatom Plus 4 spiral system (Siemens, Erlangen, Germany). Axial CT images were obtained with spiral data acquisition from the top to the bottom of the larynx, using 1-mm thick sections and a pitch of 1.0, the group reported. In addition, two sets of images were obtained at standard soft-tissue setting and at bone setting. All pre-operative exams were performed within one week before the operation, while the post-operative scans were done within one week after surgery.
"Images from the spiral data set were retrospectively reconstructed in 1-mm increments. The cricothyroid distance was determined pre- and post-operatively by counting the number of 1-mm slices between the appropriate landmarks, i.e., the lower margin of the thyroid cartilage to the upper margin of the cricoid cartilage," they said.
According to the results, CT determined that the average cricothyroid distance was 10 mm before surgery and 4 mm after the procedure. Vocal pitch elevation was greatest in the patient group with the largest reduction of the cricothyroid distance, the authors wrote.
"CT in direct axial planes perfectly delineated the laryngeal anatomy," they said. "CT allows not only a detailed assessment of laryngeal anatomy prior to and after laryngoplastic surgery, but also provides valuable information on the attainable elevation of vocal pitch."
By Shalmali Pal
AuntMinnie.com staff writer
September 13, 2000
Let AuntMinnie.com know what you think about this story.
Copyright © 2000 AuntMinnie.com
