Autologous elastic cartilage for laryngoplasty: histologic evaluation in a rabbit model

Numerical and experimental investigations on vocal fold approximation in healthy and simulated unilateral vocal fold paralysis

We have developed a novel surgical/computational model for the investigation of unilateral vocal fold paralysis (UVFP) which will be used to inform future in silico approaches to improve surgical outcomes in type I thyroplasty. Healthy phonation (HP) was achieved using cricothyroid suture approximation on both sides of the larynx to generate symmetrical vocal fold closure. Following high-speed videoendoscopy (HSV) capture, sutures on the right side of the larynx were removed, partially releasing tension unilaterally and generating asymmetric vocal fold closure characteristic of UVFP (sUVFP condition). HSV revealed symmetric vibration in HP, while in sUVFP the sutured side demonstrated a higher frequency (10 - 11%). For the computational model, ex vivo magnetic resonance imaging (MRI) scans were captured at three configurations: non-approximated (NA), HP, and sUVFP. A finite-element method (FEM) model was built, in which cartilage displacements from the MRI images were used to prescribe the adduction and the vocal fold deformation was simulated before the eigenmode calculation. The results showed that the frequency comparison between the two sides were consistent with observations from HSV. This alignment between the surgical and computational models supports the future application of these methods for the investigation of treatment for UVFP.

Histologic Evaluation of Intracordal Autologous Cartilage Injection in the Paralyzed Canine Vocal Fold at Two and Three Years

OBJECTIVE: Intracordal injection for vocal fold augmentation is easy and simple and does not require a cervical skin incision. We reported previously on the 1-year results of injected autologous auricular cartilage for volumetric augmentation in paralyzed canine vocal cord. This study evaluates the long-term histomorphologic results of injected autologous auricular cartilage for the augmentation of the paralyzed canine vocal fold at 2 and 3 years.

STUDY DESIGN AND SETTING: A prospective trial of autologous cartilage augmentation of vocal cord in animal model. Five dogs were operated on. A piece of auricular cartilage was harvested from the ear and minced into tiny chips with a scalpel. Fat was harvested from inguinal area and minced with a scalpel. The minced cartilage and fat-paste (0.2 ml) was injected using a pressure syringe into the paralyzed thyroarytenoid muscle using direct laryngoscopy. Three animals were sacrificed at 2 years, two at 3 years. Each subject underwent laryngectomy and serial coronal sections of paraffin blocks from the posterior vocal fold were made.

RESULTS: There was no significant complications perioperatively or postoperatively. The injected cartilage that seemed to have lost viability existed in the vocalis muscles until 36 months. Fibrotic change was exhibited in the surrounding injected cartilage. There were no differences between 2 and 3 years in histomorphologic results of the injected cartilage.

CONCLUSION: The autologous auricular cartilage graft is well tolerated and may be a very effective material for long-term volumetric augmentation in the paralyzed vocal cord.

Medialization thyroplasty using autologous nasal septal cartilage for treating unilateral vocal fold paralysis

Objectives

A persistent insufficiency of glottal closure is mostly a consequence of impaired unilateral vocal fold movement. Functional surgical treatment is required because of the consequential voice, breathing and swallowing impairments. The goal of the study was to determine the functional voice outcomes after medialization thyroplasty with using autologous septal cartilage from the nose.

Methods

External vocal fold medialization using autologous nasal septal cartilage was performed on 15 patients (6 females and 9 males; age range, 30 to 57 years). Detailed functional examinations were performed for all the patients before and after the surgery and this included perceptual voice assessment, laryngostroboscopic examination and acoustic voice analysis.

Results

All the patients reported improvement of voice quality post-operatively. Laryngostroboscopy revealed almost complete glottal closure after surgery in the majority of patients. Acoustic and perceptual voice assessment showed significant improvement post-operatively.

Conclusion

Medialization thyroplasty using an autologous nasal septal cartilage implant offers good tissue tolerability and significant improvement of the subjective and objective functional voice outcomes.

Soft Tissue Response of the Larynx to Silicone, Gore-Tex, and Irradiated Cartilage Implants

OBJECTIVE

The aim of the study is to compare the efficiency of three different materials (Silicone, Gore-Tex, and irradiated cartilage) used in medialization laryngoplasty. Local tissue reaction to implants in laryngeal skeleton has been examined for this purpose.

STUDY DESIGN AND METHODS

In this prospective study, New Zealand rabbits were used. Different materials have been implanted in the paraglottic space of both sides of the larynx to enable a better comparison of the different materials used. Limited medialization was applied. Special care has been taken not to narrow the airway and cause breathing problems. The reaction of the tissue in this region against the materials used has been studied. Each material was implanted 14 times in total. The rabbits were killed 6 months after the implementation to study their larynx. For each material, the fibrous capsule formation, histiocyte infiltration, foreign body giant cell infiltration, eosinophil infiltration, neutrophil infiltration, and lymphoplasmacytic infiltration levels were investigated histologically.

RESULTS

Best fibrous capsule formation has been observed around silicone. Allergic reactions and inflammatory responses were minimal for this material. Fibrous capsule formation was more limited with Gore-Tex. Some degree of chronic inflammatory response (in few cases) has been observed against this material. Severe allergic response was observed against irradiated cartilage, and the implant material was resorbed completely in most cases.

CONCLUSION

According to histopathologic results of this study (tissue compatibility of three materials), silicone is the most suited material among the study materials for medialization. Gore-Tex can also be used for this purpose. Irradiated cartilage, on the other hand, appears not to be a suitable material for medialization laryngoplasty.