The shear modulus of the human vocal fold, preliminary results from 20 larynxes

Quantification of the elastic properties of the human vocal fold provides invaluable data for researchers deriving mathematical models of phonation, developing tissue engineering therapies, and as normative data for comparison between healthy and scarred tissue. This study measured the shear modulus of excised cadaver vocal folds from 20 subjects. Twenty freshly excised human larynxes were evaluated less than four days post-mortem. They were split along the saggital plane and mounted without tension. Shear modulus was obtained by two different methods. For method 1 cyclical shear stress was applied transversely to the mid-membranous portion of the vocal fold, and shear modulus derived by applying a simple shear model. For method 2 the apparatus was configured as an indentometer, and shear modulus obtained from the stress/strain data by applying an established analytical technique. Method 1 shear model for male larynxes yielded a range from 246 to 3,356 Pa, with a mean value of 1,008 and SD of 380. The range for female larynxes was 286–3,332 Pa, with a mean value of 1,237 and SD of 768. Method 2 indentometer model for male larynxes yielded a range from 552 to 2,741 Pa, with a mean value of 1,000 and SD of 460. The range for female larynxes was 509–1,989 Pa, with a mean value of 1,332 and SD of 428. We have successfully demonstrated two methodologies that are capable of directly measuring the shear modulus of the human vocal fold, without dissecting out the vocal fold cover tissue. The sample size of nine female and 11 male larynxes is too small to validate a general conclusion. The high degree of variability in this small cohort of subjects indicates that factors such as age, health status, and post-mortem delay may be significant; and that there is range of ‘normality’ for vocal fold tissue. This project received financial support from the Engineering Physics and Science Research Council of Great Britain (EPSRC) and the Eugene B Casey Foundation (JBK).     

In vivo measurement of the elastic properties of the human vocal fold

The ability to measure the biomechanical properties of the vocal fold in vivo is both an aid to diagnosis and enhances our knowledge of how the vocal folds operate. This paper details a new instrument that is capable of taking readings of the spring rate of the vocal fold in a repeatable manner. We also present three sets of readings taken from two volunteer patients. Patient 1 was suffering from polyp growth, and the data presented are taken from both the damaged vocal fold and the healthy vocal fold. The third set of readings was obtained from a similar volunteer and taken from a healthy vocal fold. It can be seen that the data obtained from the healthy vocal folds are similar and that the data obtained from the diseased vocal fold is at variance.     

Endoscopic lateralization of the vocal fold

Vocal fold paralysis in adduction can result in significant breathing difficulties. Techniques such as vocal fold lateralization and/or arytenoidopexy help to improve respiratory function in this setting. These techniques require open approach or specific instruments. The authors describe an original vocal fold lateralization technique performed exclusively via an endoscopic approach. This technique helps to enlarge the glottic aperture, while preserving laryngeal architecture, and permanently improves respiratory function in patients with vocal fold paralysis in adduction.     

声带振动功能的定量检测

目的：探讨声带振动功能的定量检测技术及其影响因素。方法：应用计算机软件,分析６０例正常人动态喉镜图像和电声门图参数,结合性别、频率和声强,进行统计分析。结果：声带振动周期中发声频率增加伴随开放相相对延长（ＣＱ减小,ＯＱ增大）,而声强增加则开放相相对缩短,且渐闭相缩短更明显（ＯＱ减小,ＳＱ增大）,男性较女性声门闭合相长（ＯＱ小）。发声时声带闭合的速度大于开放的速度（ＣＶ〈ＯＶ,ＣＣＰ〈ＣＯＰ）。结论     

Functional results after external vocal fold medialization thyroplasty with the titanium vocal fold medialization implant

OBJECTIVES/HYPOTHESIS: A persistent insufficiency of glottal closure is mostly a consequence of a unilateral vocal fold movement impairment. It can also be caused by vocal fold atrophy or scarring processes with regular bilateral respiratory vocal fold function. Because of consequential voice, breathing, and swallowing impairments, a functional surgical treatment is required. The goal of the study was to outline the functional results after medialization thyroplasty with the titanium vocal fold medialization implant according to Friedrich. METHODS: In the period of 1999 to 2001, an external vocal fold medialization using the titanium implant was performed on 28 patients (12 women and 16 men). The patients were in the age range of 19 to 84 years. Twenty-two patients had a paralysis of the left-side vocal fold, and six patients, of the right-side vocal fold. Detailed functional examinations were executed on all patients before and after the surgery: perceptive voice sound analysis according to the "roughness, breathiness, and hoarseness" method, judgment of the s/z ratio and voice dysfunction index, voice range profile measurements, videostroboscopy, and pulmonary function tests. In case of dysphagia/aspiration, videofluoroscopy of swallowing was also performed. The respective data were statistically analyzed (paired t test, Wilcoxon-test). RESULTS: All patients reported on improvement of voice, swallowing, and breathing functions postoperatively. Videostroboscopy revealed an almost complete glottal closure after surgery in all of the patients. All voice-related parameters showed a significant improvement. An increase of the laryngeal resistance by the medialization procedure could be excluded by analysis of the pulmonary function test. CONCLUSIONS: The results confirm the external medialization of the vocal folds as an adequate method in the therapy of voice, swallowing, and breathing impairment attributable to an insufficient glottal closure. The titanium implant offers, apart from good tissue tolerability, the advantage of an easy, time-saving, and individually adjustable application during the operation.     

Long-term results of autologous fascia in unilateral vocal fold paralysis

The objective of this retrospective clinical review was to evaluate the long-term results of injection laryngoplasty with autologous fascia as a single, primary procedure in unilateral vocal fold paralysis. Forty-three patients who had undergone injection laryngoplasty between 1996 and 2003 entered the study. Clinical examination and videostroboscopy were performed and the voice handicap index was analyzed postoperatively. Pre- and post-operative evaluation included computerized acoustic analysis and perceptual evaluation. The results remained stable 3–10 years and were not affected by the length of follow-up, the delay from paralysis to surgery, or the age of the patient. Although most mean values of voice parameters were significantly improved, results in individual patients were difficult to predict. Poor results were especially related to cases caused by intrathoracic lesions. Wide glottal gaps should not be treated with fascia injection. Fascia is a stable graft and most suitable for cases with less severe glottal insufficiency.     

Composite myo-mucosal reconstruction of the vocal fold

It is well established that after cordectomy or radiation therapy for early glottic carcinomas varying disturbances of the voice occur. This has led some clinicians to consider the need for surgical reconstruction of the vocal fold. Since functional results desired have still not been achieved, vocal fold reconstruction was performed using a combination of the muscular flap described by Pogosov and the free mucosal transplant reported by Isshiki. This surgical approach has now been performed on 11 cases with excellent functional results. The technique has provided a suitable mass of the reconstructed vocal fold and also allows very close contact between the vocal folds during the closed phase of the vibratory cycles. Postoperative voice quality has been almost within physiological limits.     

Treatment of vocal fold immobility by injectable homologous collagen: short-term results

Various implant materials have been used to treat glottic insufficiency by means of intracordal injection. So far, autologous fat is the most commonly used. Homologous collagen is a new injectable acellular graft material. This collagen, made of 200- particles, is delivered as a freeze-dried powder in a 1-cc-unit syringe and is rehydrated with standard saline solution prior to injection. A prospective study was conducted on 23 patients with unilateral vocal fold paralysis. All injections were performed under general anesthesia using the collagen injection system and a 25-gauge needle. A mean quantity of 1.05 ml (SD: 0.41) of collagen was injected as much as possible in the deep part of the lamina propria. Voicing was resumed after 2 days. The mean follow-up was of 8 months (range: 2–18). Functional results were measured according to the ELS protocol. G(rade), R(oughness) and B(reathiness) according to Hirano were reported on a four-point grading scale showing an improvement from 2.13 to 1.13 for G (P<0.001), from 1.50 to 0.82 for R (P<0.002) and from 1.73 to 1.05 for B (P<0.001). The parameters selected for videolaryngostroboscopy, G(lottal) (Clo)sure, (R)egularity, (M)ucosal (W)ave and (Sym)metry, were measured on a visual analog scale. They showed an improvement from 23 to 19 for Clo (P=0.087), from 15 to 6 for R (P=0.001), from 15 to 11 for MW (P=0.039) and from 17 to 8 for Sym (P=0.001). For the aerodynamic parameters, the maximum phonation time (MPT) and the phonation quotient (PQ) showed an improvement from 5.8 to 8.9 s (P=0.002) and from 704.5 to 449.7 ml/s (P=0.004), respectively. The acoustic parameters were improved from 5.3 to 3.6 (P=0.045) for the jitter (%), they didnt change for the shimmer [(%): 2.4], and they were improved non-significantly from 187.9 to 218.7 Hg for the frequency range. The lowest level intensity was non-significantly increased from 49.6 to 51.3 dB. Regarding the subjective evaluation, the Voice Handicap Index (VHI) was improved from 65 to 37. To date, no homologous collagen-related morbidity has been observed. Injectable homologous collagen appears to be safe and suitable for injection laryngoplasty. Long-term results are pending.     

Rejection of injectable silicone “Bioplastique” used for vocal fold augmentation

A rare case of repeated granulomatous inflammation after silicone injection laryngoplasty for vocal fold immobility as well as its treatment by endoscopic approach is reported. The patient presented a right-sided vocal fold immobility after laryngeal trauma and remained dysphonic despite of logopedic voice therapy because of severe glottal insufficiency. An endoscopic transoral intrafold silicone injection was applied to improve the vocal function. Silicone granuloma inflammation was observed 8 days after the vocal fold augmentation. Oral broad-spectrum antibiotics and corticosteroids did not improve the inflammation. A cordotomy was performed to remove the silicone implant. After 3 months, a second endoscopic surgical intervention was necessary to remove a recurrent silicone granuloma. Eight months after the second surgical intervention, the inflammation had disappeared. An autologous fat injection to restore the glottal closure was performed successfully. Type IV contact allergy was excluded with an epicutaneous patch and scratch test with components of the silicone implant. Clinical and treatment observations are reported and the literature on complications of intrafold injected silicone for vocal fold augmentation is reviewed.     

Detection of hormone receptors in the human vocal fold

Until now only limited and controversial data are available concerning the presence of steroid hormone receptors in the human vocal fold. A sum of 140 slides from 104 patients were investigated including 25 Reinke's edemas, 19 cases of recurrent respiratory papillomatosis, 19 polyps, 10 epithelial hyperplasias without or with dysplasias, 4 carcinomas in situ, 20 laryngeal carcinomas as well as 7 fresh cadaver samples without macroscopic alterations. The median patient age was 58 years. Paraffin-embedded tissue was incubated with monoclonal antibodies for estrogen-alpha, androgen and progesterone. Androgen receptors were expressed most frequently, followed by estrogen receptors, whereas no progesterone receptors were identified. Receptor staining could be detected with different densities and locations within the different vocal fold pathologies, but not in the autopsy samples. Our study could clearly demonstrate the presence of hormone receptors in the human vocal fold. Androgen receptors were most frequently detected, especially in the basal and intermediate layer of the stratified epithelium and the lamina propria. Whether the high incidence of steroid hormone receptors in some vocal fold pathologies has implications on their pathogenesis must be evaluated by further studies.     

Videostroboscopic assessment of unilateral vocal fold paralysis after augmentation with autologous fascia

Vocal fold augmentation by injection laryngoplasty is a simple and fast procedure. The aim of this prospective study was to assess the glottal closure and the travelling mucosal wave by videostroboscopic images after autologous fascia augmentation in unilateral vocal fold paralysis (UVFP) with a special reference to objective analysis of voice. A total of 14 UVFP patients with poor voice and open glottal gap were assessed by videostroboscopy, blinded perceptual evaluation of running speech and acoustical analysis of sustained vowel. Data were collected before the procedure and at a supplementary evaluation 5–32 months (mean: 13 months) after injection of autologous fascia deep into the paralysed vocal fold. Mean age was 59 years; there were eight women and six men. Frame-by-frame video analysis revealed that before the operation 10 out of 12 had large glottal gaps without any contact between vocal folds on phonation. After the procedure seven gaps were completely closed, four partly, and two had no mucosal contact in stroboscopic examination. Maximum gap between vocal folds decreased from 7.21 units to 1.65 units (paired t-test P<0.001). Mucosal wave amplitude symmetry and phase synchrony were present in most subjects with partial closure and phase synchrony in every patient with a proper glottic closure. A panel of listeners rated voice to be significantly better (P<0.01) ) after the procedure, and the improvement in acoustical parameters was also statistically significant (P<0.01). There was a good correlation between objective voice analysis and videostroboscopy. Residual glottal gap was the major reason for less than optimal postoperative voice. No signs of hampered mucosal wave were noticed. Videostroboscopy and objective voice analysis suggest that augmentation by autologous fascia does not induce scar or fibrous tissue in the subepithelial space. Slight over-correction should be attempted initially in order to accomplish sufficient augmentation. This might enhance complete glottic closure and improve the outcome.