Using peak direct subglottic pressure level as an objective measure during medialization thyroplasty: a prospective study

Type I medialization thyroplasty (MT) was introduced by Isshiki more than 40 years ago. It is one of the most widely used surgical options to correct glottic insufficiency. Intraoperatively, the surgeon relies solely on perceptual subjective measures to help to achieve an optimal glottic closure by bringing the affected vocal fold closer to the midline in order to close the glottic gap. One of the challenges of MT is the persistence of symptoms due to incorrect choice of implant size. As of now, no standard objective measure is being used to determine the optimal implant size needed to achieve the glottic closure required. Peak direct subglottic pressure (PDSGP) is one of the aerodynamic objective measurements of vocal efficiency that significantly increases in cases of glottic insufficiency. It is easily measured during MT by inserting a catheter through the cricothyroid membrane. A prospective study was carried out on patients undergoing MT using the Montgomery Implant^®. Choice of implant size was carried out based on the standard perceptual subjective assessment by the operating surgeon and was based on degree of glottic closure and voice quality. PDSGP was recorded for each implant size and then we tested the agreement between the chosen implant size and the lowest PDSGP. The agreement between the implant size of choice and the lowest PDSGP recorded was 62.5 % [CI 44–79 %]. PDSGP was easy to measure and resulted in no complications. PDSGP is a useful tool that could assist in the choice of the correct implant size needed during MT. Level of evidence: 4.