Histological investigation of liposuctioned fat for injection laryngoplasty

Vocal Fold Fat injection for Glottic Insufficiency: Systematic Review

Vocal fold fat injection is a technique for treating glottic insufficiency (GI) resulting from various conditions. The use of fat as a graft has several advantages over other grafts. Similar pliability, and vibratory characteristics as a normal vocal fold, not causing foreign body reactions, having the potential to contain stem cells, and often can be done in the office. Long-term results, however, are unpredictable. The objective of this study is to carry out a systematic review of published articles using the technique of fat injection in the vocal folds.

STUDY DESIGN

Systematic review.

REVIEW METHODS

A literature search was conducted utilizing the combination of the following keywords "vocal folds fat injection," "laryngoplasty," and "autologous fat injection vocal folds." The criteria inclusion of the study for the systematic review were based on PICOTS (population, intervention, comparison outcome, timing, and setting) and Preferred Reporting Items for Systematic Reviews and Meta-analyses statements. Outcomes reviewed included technique, study duration, perceptual and acoustic analysis, and quality of life preoperation and 1-year postoperation.

RESULTS

A systematic review on PubMed, Cochrane, and Embase databases included 13 studies analyzing the data of 472 patients, that had fat injection laryngoplasty for treatment of GI. The causes of GI varied substantially across studies. Considerable heterogeneity across studies was found, including technique for harvest, processing the fat, site of injection, and acoustic analysis. In the studies that measured maximum phonation time (MPT) there was a significant improvement in a follow-up of at least 1 year after the injection. The patient's perception of vocal quality, measured by the Voice Handicap Index, also showed significant improvement in several studies after fat injection laryngoplasty.

CONCLUSION

Fat injection laryngoplasty seems to be safe and effective for GI for at least 12 months. Multiple studies show favorable outcomes, but the lack of control groups, the heterogeneity in inclusion criteria, nonstandardized techniques, and objective voice evaluations limit this evaluation.

Autologous Fat Injection Laryngoplasty for Unilateral Vocal Fold Paralysis

BACKGROUND

Unilateral vocal palsy (UVFP) affects the voice and swallowing function and could be treated by various materials to achieve improved mucosal wave and better closure during phonation. Injection laryngoplasty is considered an exemplary method for these patients and could be injected as early as possible. We conducted a systematic review and meta-analysis for the subjective and objective outcomes of autologous fat injection laryngoplasty (AFIL) and assessed the effects for patients with UVFP.

METHODS

We searched studies from PubMed and EBSCO databases with PRISMA appraisal to search for articles about the effects of AFIL on UVFP. The published articles were reviewed according to our inclusion and exclusion criteria. The short- and long-term outcomes of perceptual, acoustic analysis, and quality of life were also analyzed by meta-analysis.

RESULTS

Eleven articles were reviewed, and seven studies were selected for meta-analysis. AFIL improves the perceptual outcome and some voice parameters in short-term and long-term results, i.e., jitter, shimmer, and maximal phonation time (MPT). It also significantly improved the voice handicap index (VHI) in the long term, suggesting an increase in quality of life.

CONCLUSIONS

AFIL is considered a reliable treatment method for UVFP and could even last for over 12 months.

Autologous Lipoaugmentation Long-Term Clinical Outcomes: A Systematic Review

OBJECTIVES/HYPOTHESIS

Vocal fold (VF) lipoaugmentation can be employed to treat glottal insufficiency although variable data exist on its length of effectiveness. We aimed to review published long-term outcomes following lipoaugmentation across the literature and compile outcome data.

STUDY DESIGN

Systematic review.

METHODS

A systematic search in September 2020 of PubMed, MEDLINE, Cochrane Library, and Web of Science used the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to identify 128 relevant articles related to VF lipoaugmentation effectiveness duration. Primary search terms included the following: vocal cord, fat, lipo, and atrophy. Forty-eight full-text articles were reviewed and 31 were included in the final analysis. Primary endpoints included the following: duration of effectiveness per patient-reported outcome measures, objective findings, and additional procedures performed. In addition, fat harvest location and processing techniques were recorded.

FINDINGS

Thirty-one studies totaling 764 patients were included in the review. Indications for augmentation were VF paralysis (N = 690) and atrophy (N = 74). Fat was harvested from the abdominal region in 21 studies (529 patients), the thigh/abdomen in 5 studies (91 patients), and buccal/submental region in 2 studies (33 patients). Processing techniques and injectable volume varied. Across included studies, only 11 of 764 patients (1.4%) reported no improvement in voice and/or swallowing. Within the first year, 71 of 608 patients (11.7%) reported a regression toward baseline. Beyond 1 year and up to 8 years, 27 of 214 patients (12.6%) reported regression from initial improvement. Thirty-three patients underwent additional procedures.

CONCLUSION

Although improvements in voice and swallowing after lipoaugmentation taper over time, most patients experienced long-term benefit. Laryngoscope, 2021.

Computed tomographic assessment of autologous fat injection augmentation for vocal fold paralysis

Objective

To perform a quantitative computed tomography (CT) assessment of short‐ and long‐term outcomes of autologous fat injection augmentation in patients with unilateral vocal fold paralysis.

Study Design

Retrospective case series.

Methods

Twelve patients who had undergone autologous fat injection augmentation for unilateral vocal fold paralysis in our hospital between 2011 and 2015 were enrolled in this study. The autologous fat for injection was acquired from periumbilical subcutaneous tissue and was injected orally using a special‐purpose laryngeal injection needle. To evaluate the injected fat at the follow‐up assessments, CT was performed at several times after surgery in clinical practice. All thin‐section CT images were transferred to a workstation, and the volume of the injected fat was calculated.

Results

Patients comprised 6 men and 6 women with a mean age at the time of surgery of 62.9 years (range, 46–82 years). The actual injected fat volume was 1.1–2.5 ml (mean, 1.6 ml). In seven patients assessed by CT two days after surgery, the average residual rate of the injected fat was 63.9%. The mean residual rates of the injected fat were 30.0% at 3 months, 33.7% at 6 months, 29.2% at 12 months, and 32.0% at 24 months.

Conclusions

Although the injected fat volume decreased within the first three months and the residual rate of the injected fat was 30.0% at three months after injection, the residual fat volume remained at the same level for 24 months after injection.

Level of Evidence

4

Effect of sugarcane biopolymer gel injected in rabbit vocal fold

INTRODUCTION

Alterations in the vocal folds that involve volume reduction and glottal closure failure result in exaggerated air escape during speech. For such situations, the use of implants or grafts of different materials has been proposed.

OBJECTIVE

To define the effect of sugarcane biopolymer gel when implanted in the vocal folds of rabbits.

METHODS

This was an experimental study. The vocal folds of rabbits injected with sugarcane biopolymer and saline solution were histologically evaluated after 21 and 90 days.

RESULTS

Mild to moderate inflammation and increased volume were observed in all vocal folds injected with biopolymer, when compared to controls. There were no cases of necrosis or calcification.

DISCUSSION

This study showed higher inflammatory reaction in cases than in controls and biopolymer biointegration to the vocal fold. This fibrogenic response with absence of epithelial repercussions suggests that the biopolymer in its gel form can be bioactive and preserve the normal vibratory function of the epithelium.

CONCLUSION

We show that in spite of producing an inflammatory reaction in vocal fold tissues, the material remained in vocal fold throughout the study period.

Buccal fat augmentation for insufficient neoglottal closure after supracricoid laryngectomy with cricohyoidoepiglottopexy

OBJECTIVE

Supracricoid laryngectomy with Cricohyoidoepiglottopexy (SCL-CHEP) is a functional organ preservation surgery for laryngeal cancers. Post-operative laryngeal function is generally promising. Some patients, however, cannot attain satisfactory functional results because of an excessively wide neoglottis resulting in an insufficient neoglottal closure. Autologous buccal fat augmentation was conducted to correct the insufficiency.

PATIENTS AND METHODS

Two patients underwent intervention. Under general anesthesia, autologous fat was harvested from the buccal fat pad. Fat tissue was injected into the widest plane of the neoglottis under direct laryngoscopy; a navigation system was incorporated to identify the responsible site. Acoustic, aerodynamic, and perceptual analyses along with videofluoroscopic swallowing study and screening questionnaires were used for functional evaluation.

RESULTS

A total of 0.8ml (Case 1) and 0.7ml (Case 2) of fat tissues were injected into the submucosal space of the responsible sites. Both patients experienced functional improvement subjectively after augmentation; psychological parameters for voice and swallowing also improved.

CONCLUSIONS

Buccal fat augmentation to correct insufficient neoglottal closure after SCL-CHEP was technically feasible. A navigation system was helpful for confirmation. Fat absorption occurred and one third of the volume remained at 3 and 6 months. Although, vocal measurements remained unchanged, psychological parameters for voice and swallowing improved.

[Glutaraldehyde-preserved and lyophilized bovine pericardium as materials for medialization of the vocal folds in an animal model]

INTRODUCTION

Glutaraldehyde-preserved bovine pericardium (GBP) and lyophilized GBP (LGBP) have been used successfully in repairing several anatomical defects, but their effectiveness and safety as implants to vocal cords (VC) have not been reported.

OBJECTIVE

The aim of this study was to evaluate the use of GBP and LGBP as materials for medialization thyroplasty, as well as to assess the endoscopic, macroscopic and microscopic VC changes after medialization in an experimental canine model.

MATERIAL AND METHODS

In 12 healthy mongrel dogs, the right VC were medialized using pericardium and the left with polytetrafluoroethylene (PTFE). Group 1 (n=6): GBP and Group 2 (n=6): LGBP. The surgical manoeuvrability of the implants was compared. The animals were evaluated clinically and endoscopically. Three months after surgery, the larynges were assessed macro- and microscopically.

RESULTS

Both GBP and LGBP implants showed better surgical manoeuvrability (Kruskal-Wallis, P=.005). Endoscopic and macroscopic studies showed no evidence of granulomas, absorption or extrusion of the implant. At the end of the study, greater thickness was observed in VC implanted with PTFE. Microscopically, all the VC developed fibrous capsules surrounding the implants and similar chronic inflammation reaction. The VC implanted with PTFE presented eosinophilic infiltration (Kruskal-Wallis, P<.05).

CONCLUSION

Both GBP and LGBP can be used as implants for VC medialization because they are biocompatible, have easy surgical manoeuvrability, do not suffer absorption, migration or extrusion and produce inflammation reactions similar to those of PTFE.

Fat grafting to the breast and adipose-derived stem cells: recent scientific consensus and controversy

Recent technical advances in fat grafting and the development of surgical devices such as liposuction cannulae have made fat grafting a relatively safe and effective procedure. However, new guidelines issued by the American Society of Plastic Surgeons in 2009 announced that fat grafting to the breast is not a strongly recommended procedure, as there are limited scientific data on the safety and efficacy of this particular type of fat transfer. Recent progress by several groups has revealed that multipotent adult stem cells are present in human adipose tissue. This cell population, termed adipose-derived stem cells (ADSC), represents a promising approach to future cell-based therapies, such as tissue engineering and regeneration. In fact, several reports have shown that ADSC play a pivotal role in graft survival through both adipogenesis and angiogenesis. Although tissue augmentation by fat grafting does have several advantages in that it is a noninvasive procedure and results in minimal scarring, it is essential that such a procedure be supported by evidence-based medicine and that further basic scientific and clinical research is conducted to ensure that fat grafting is a safe and effective procedure.

Comparative study of framework surgery and fat injection laryngoplasty

OBJECTIVE

To evaluate differences between the functional results of framework surgery and autologous fat injection laryngoplasty, for patients with unilateral vocal fold paralysis.

STUDY DESIGN

Sixty-two patients underwent framework surgery, while 64 received autologous fat injection laryngoplasty. Voice function before and after both procedures was assessed using aerodynamic and acoustic analysis, with differences evaluated using paired t-test in both groups.

RESULTS

In both groups, all parameters improved significantly after surgery, compared with before surgery. Post-operative improvement in all parameters was significantly greater after fat injection laryngoplasty, compared with framework surgery.

CONCLUSION

Autologous fat injection laryngoplasty was thus found to be a more effective and reliable therapy for improving voice function in patients with vocal fold paralysis, compared with framework surgery.

Efficacy of autologous fat injection laryngoplasty with an adenoviral vector expressing hepatocyte growth factor in a canine model

Objective:

The effectiveness of autologous fat injection laryngoplasty may be reduced by resorption of injected fat tissue. The aim of the present study was to clarify the efficacy of fat injection laryngoplasty using autologous fat plus a replication-defective adenoviral vector expressing hepatocyte growth factor, regarding reduction of injected fat tissue resorption.

Material and methods:

Four female beagle dogs were used in this study. After sedation, a direct laryngoscope was introduced to enable visualisation of the larynx. In each dog, harvested autologous fat plus an adenoviral vector expressing hepatocyte growth factor was injected into the right true vocal fold, and harvested fat plus an adenoviral vector expressing no gene was injected into the left true vocal fold. A total laryngectomy was performed one year after the intracordal fat injection. Coronal sections of the resected whole larynges were made and the following parameters assessed using light and electron microscopy: size of fat area; number of vasculoendothelial cells surrounding adipocytes; and shape of injected adipocytes in the vocal fold.

Results:

The fat area was significantly larger and the number of vasculoendothelial cells surrounding adipocytes significantly greater in the intracordal fat injection containing adenoviral vector expressing hepatocyte growth factor, compared with the control intracordal fat injection containing adenoviral vector expressing no gene. When viewed under electron microscopy, the injected adipocytes were observed to have grafted better in the intracordal fat injection with hepatocyte growth factor adenoviral vector, compared with the control intracordal fat injection with adenoviral vector expressing no gene.

Conclusions:

Injection into the vocal fold of autologous fat containing an adenoviral vector expressing hepatocyte growth factor can reduce subsequent resorption of injected fat.

[Voice reconstruction of the recurrent laryngeal nerve after nerve resection]

Our treatment of choice in voice reconstruction for recurrent laryngeal nerve (RLN) resection is concurrent nerve reconstruction. If this is not possible, we secondarily inject fat. We studied postoperative voice function and the feasibility of this voice reconstruction treatment strategy. Subjects were 39 patients with advanced thyroid cancer having the primary lesion resected together with RLN between 2001 and 2007. Of these 39, 9 underwent concurrent reconstruction by directly anastomosing the ansa cervicalis to the peripheral RLN. Fat was secondarily injected in 25 and 5 did not undergo any reconstruction. We found that: 1) Postoperative maximum phonation time (MPT), mean flow rate (MFR) and pitch perturbation quotient (PPQ) in the direct anastomosis group were significantly better than in the nonreconstruction group (p < 0.05). 2) Postoperative MPT, MFR, and PPQ in the fat injection group were significantly better than in the nonreconstruction group (p < 0.05). 3) MPT in the fat injection group was significantly better than in the direct anastomosis group one month postoperatively (p = 0.007), although this finding was reversed six months postoperatively (p = 0.08). 4) MFR in the fat injection group tended to be better than the direct anastomosis group one month postoperatively (p = 0.1), although this finding was reversed six months postoperatively (p = 0.1). We thus recommend concurrent voice reconstruction by direct anastomosis in conjuction with nerve resection.

Intracordal fat assessment by 3-dimensional imaging after autologous fat injection in patients with thyroidectomy-induced unilateral vocal cord paralysis

BACKGROUND

Complications of thyroidectomy are the most frequent cause of unilateral vocal cord paralysis (UVCP) in Taiwan. Autologous fat injection for UVCP is a well-established procedure for temporary symptom relief. The aims of this study were to identify the long-term residual fat volume by 3-dimensional computed tomography (3-D CT) and to investigate the voice outcome.

METHODS

During this cross-sectional study, 28 consecutive patients who had undergone lipoinjection surgery for symptomatic UVCP resulting from thyroidectomy were enrolled. They received 3-D CT evaluations of the larynx and upper airway after lipoinjection surgery to assess the residual fat volume.

RESULTS

The mean duration from lipoinjection surgery to 3-D CT study was 26 months (range, 12-58). The mean residual fat volume remained consistent (0.39 +/- 0.35 mL; range, 0.01-1.6). The maximal phonation time, s/z ratio, jitter, and harmonic-to-noise ratio were significantly improved during follow-up.

CONCLUSION

Injected fat can survive chronically and provide clinically important improvement in voice in the patients with throidectomy-induced UVCP.