Vocal fold paralysis (VFP) is a disorder caused by damage to the recurrent laryngeal nerve. VFP impairs breathing, swallowing, and vocal function. A number of surgical approaches to treating VFP have been proposed, notably injection laryngoplasty, laryngeal framework surgery including medialization thyroplasty (MT) and arytenoid adduction (AA), and laryngeal reinnervation. MT can be employed in patients with more severe glottic insufficiency and has several benefits over injection, including improved preservation of the mucosal wave, permanence, ability to revise or remove the implant, and the ability to correct a more severe glottal gap. However, numerous challenges encountered by MT have been the subject of extensive research into improving the procedure. Carving a Silastic implant during surgery can result in suboptimal shaping and prolong procedural duration, resulting in increased intraoperative edema and decreased ability to judge intraoperative voicing accurately. Several alternatives to Silastic have been proposed, including hydroxyapatite, the titanium vocal fold medializing implant, and Gore-Tex. These implants represent valuable innovations and can be used effectively to treat VFP;however, they cannot be modified postoperatively without a revision thyroplasty. Postoperative complications such as penetration and breathy phonation due to hypoadduction or dyspnea and pressed phonation due to hyperadduction are not uncommon;therefore, being able to adjust the degree of medialization postoperatively is desirable. We present the adjustable balloon implant (ABI) which combines customizability with postoperative adjustability. Additionally, the ABI offers the benefits of traditional thyroplasty and injection laryngoplasty. It is reversible, does not alter the structureof the lamina propria, and preserves the mucosal wave as with thyroplasty. It also offers incremental medialization as with injection laryngoplasty. A silicone balloon which can be filled with saline is introduced into the larynx via a standard thyroplasty window and stabilized with a metal frame that prevents implant extrusion and ensures the force of the implant is directed medially. Most importantly, the volume of the implant (and therefore the degree of vocal fold medialization) can be adjusted postoperatively without the need for a revision thyroplasty. While promising in our preliminary investigation, improvements to the shape and insertion method of the ABI would enhance clinical utility. Experiments will be conducted using the excised larynx bench apparatus which offers a controlled environment with repeatable conditions and immediately available information on treatment efficacy.
Three aims are proposed to improve the ABI: 1) determining if a wedge-shaped balloon provides better medialization than a spherical balloon;2) determining if the ABI can be coupled with AA;and 3) determining if the ABI can be inserted via an anterior microthyrotomy, eliminating the need for a large neck incision and potentially transforming thyroplasty from a highly invasive 1.5 hour operation to a minimally invasive 30 minute minor procedure.
Glottic insufficiency including vocal fold paralysis is a common problem requiring surgical intervention. Inappropriate medialization during medialization thyroplasty can result in hypoadduction causing breathy phonation and increased risk of aspiration or hyperadduction causing pressed phonation and dyspnea. Current implants for medialization thyroplasty are limited by a lack of customizability according to patient anatomy and lack of postoperative adjustability. The adjustable balloon implant can be filled to different volumes according to larynx size and can also be adjusted easily postoperatively without the need for a revision thyroplasty. This proposal describes three basic science experiments designed to improve implant shape and insertion method to enhance its clinical utility.
