Fixed Vocal Cord in Laryngeal Cancers: Mechanisms and Spiral CT Findings

Lee, Sung Gap; Nam, Sang Hwa; Han, Guk Sang; Jung, Doo Young; Kim, Hak Jin; Lee, Jun Woo; Kim, Byung Soo; Wang, Soo Guen

Abstract

PURPOSE
To analyze the causes of vocal cord fixation in laryngeal cancer and to demonstrate its spiral CT findings.
MATERIALS AND METHODS
We retrospectively applied the five pathologic mechanisms of vocal cord fixationto spiral CT findings and evaluated mechanisms of fixed vocal cord in 16 patients with laryngeal cancer of T3 or more on staging. CT findings of another six patients (T2) showing one or more suspicious mechanisms of vocal cord fixation in conventional CT were compared with those of the 16 patients (T3 or more).
RESULTS
In 16 patients with laryngeal cancer of T3 or more, the most common finding of vocal cord fixation was the complete replacement of the true vocal cord (including the thyroarytenoid and vocalis muscle) by the tumor and tumor invasion of the paralaryngeal space (n = 16). Other findings were tumor invasion and fixation of the cricoarytenoid joint (n = 9), interference with cord mobility by the bulky mass (n = 6), tumor invasion of the thyroid cartilage, with vocalcord fixation (n = 4) and subglottic tumor spread (n = 3). In another six patients (T2) with suspicious vocal cordfixation, conventional CT showed partial vocal cord invasion and intact or minimal invasion of the paralaryngeal space (n = 3), a bulky mass without vocal cord invasion (n = 1) and subglottic extension but movable vocal cord (n= 2).
CONCLUSION
Although the cause of vocal cord fixation from laryngeal cancer may be due to one of five patterns of cancer spread, or to a combination of these, the most common spiral CT finding is complete replacement of true vocal cord by the cancer and tumor invasion of the paralaryngeal space. Accurate evaluation of vocal cord fixation and the extent of the tumor could be evaluated with spiral CT using the breathing technique.