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Eur J Cardiothorac Surg 2003;23:477-483
© 2003 Elsevier Science NL

External vocal fold medialization in patients with recurrent nerve paralysis following cardiothoracic surgery

^a Section of Phoniatrics-Logopedics, Department of Otorhinolaryngology, General Hospital, University Hospital of Vienna, Vienna, Austria
^b Division of Cardiothoracic Surgery, Department of Surgery, General Hospital, University Hospital of Vienna, Vienna, Austria

Received 2 September 2002; received in revised form 28 November 2002; accepted 11 December 2002.

^* Corresponding author. Tel.: +43-1-40400-3310; fax: +43-1-40400-3332
e-mail: berit.schneider{at}akh-wien.ac.at

	Abstract

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
Objectives: Recurrent laryngeal nerve injury is a possible complication following cardiothoracic surgery. Due to insufficient glottal closure, dysphonia and dysphagia with aspiration may occur. The purpose of the study was to outline the effect of vocal fold medialization thyroplasty on voice, swallowing and breathing impairments. Methods: Between 1999 and 2001, medialization thyroplasty using the titanium implant (TVFMI^®) according to Friedrich was performed in 14 patients with postoperative left-sided recurrent nerve paralysis (five female and nine male patients, mean age 64 years) by an external approach. Previous surgical procedures comprised six lobectomies (combined with resection and replacement of the subclavian artery in one case), two pneumonectomies, one resection of a schwannoma in the aortopulmonary window, two replacements of the descending aorta, one aortocoronary bypass procedure (with LIMA), and two esophageal resections using Akiyama technique, respectively. Before and after thyroplasty, the patients underwent an otolaryngological/phoniatric examination including videostroboscopy, voice sound analysis, voice range profile measurement, pulmonary function testing, and in selected cases videofluoroscopy of swallowing. Results: Following thyroplasty, all patients reported on subjective improvement of voice, swallowing and breathing functions. Videostroboscopy revealed an improved glottal closure (six complete, six with posterior gap). All voice related parameters (e.g. roughness, breathiness, hoarseness, maximum sound pressure levels of the singing and shouting voices) were significantly improved. Conclusions: Due to potential risk of recurrent nerve alteration in left-sided intrathoracic procedures, a preoperative and postoperative laryngoscopic examination is recommended. The external medialization of the vocal folds can be regarded as an excellent method for improvement of voice, swallowing and breathing, in particular, when the quality of life is impaired due to persistent recurrent nerve paralysis.

Key Words: Recurrent laryngeal nerve paralysis • Cardiothoracic surgery • Thyroplasty • Hoarseness • Aspiration

	1. Introduction

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
A variety of potential complications associated with cardiothoracic surgery has been reported [1–5]. Even though rare, vocal fold paralysis is a well-documented possible complication of cardiothoracic surgery caused by recurrent laryngeal nerve stretching, pressure or injury [6]. The anatomy of the right recurrent laryngeal nerve makes it vulnerable as it runs around the subclavian artery. The left one is more frequently exposed to injury during cardiothoracic interventions because of its path around the aortic arch. The paralyzed vocal fold is usually fixed in a paramedian position with an insufficient glottal closure.

Main symptoms of unilateral recurrent nerve paralysis are voice problems with hoarseness, breathiness and reduced vocal efficacy, swallowing impairment with aspiration and reduced breathing control. In combination with reduced laryngeal sensibility and insufficient glottal closure, silent aspiration causing pneumonia may occur, with the recovery of patients after cardiothoracic interference being additionally impaired. If a logopedic therapy cannot restore a sufficient voice and swallowing function, a phonosurgical intervention is often indicated. The newly developed modifiably preformed titanium vocal fold medialization implant (TVFMI^®) according to Friedrich allows a precise and atraumatic medialization of the altered vocal fold to be obtained. This method combines good positioning control with easy adjustment and excellent postoperative functional results [7]. The purpose of this prospective study was to investigate the effect of external medialization thyroplasty on impairments of voice and swallowing in patients with recurrent nerve paralysis due to cardiothoracic surgery.

	2. Material and methods

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
2.1. Patients
The present study included 14 patients (five females and nine males) who had undergone cardiothoracic surgery between 1995 and 2001. The mean age was 62.8 years (range: 43–83 years). Eleven procedures had been performed at the Department of Surgery/Division of Cardiothoracic Surgery of the University Hospital Vienna, two in private hospitals, and one in a community hospital. All patients presented postoperative hoarseness; thus an otolaryngological examination was performed. In ten of these patients, recurrent nerve paralysis was diagnosed before discharge from hospital, whereas in four patients, the diagnosis was confirmed 1.5–3 months postoperatively. In all cases, the left recurrent nerve was affected. All patients complained not only about hoarseness, but also about reduced vocal efficacy, disturbed breathing control, problems with coughing, dysphagia, and hence impairments of their social life. In addition to this, four patients reported an occasional aspiration (degree 1), seven on intermittent aspiration with liquids (degree 2) and one on severe aspiration with liquids and solids (degree 3) according to the clinical classification by Miller and Eliachar [8].

Between November 1999 and April 2002, all patients underwent a left-sided external vocal fold medialization using the titanium vocal fold medialization implant under local anesthesia supplemented by intravenous sedation (‘sedoanalgesia’). The procedure was performed 2.1–86.1 months (median: 8.6 months) after cardiothoracic intervention; the follow-up after thyroplasty ranged from 5 to 33 months.

2.2. Primary cardiothoracic surgery
The underlying diagnosis and cardiothoracic surgical procedures are summarized in Table 1. Indication for surgery was a bronchial carcinoma in seven patients, including five cases of non-small cell lung cancer (NSCLC; three squamous cell carcinomas, two adenocarcinomas) and two cases of small cell lung cancer (SCLC). Clinical stages comprised stage I (n=2), II (n=2), III A (n=1), and III B (n=2). One patient (patient 6) had a pulmonary metastasis of colon carcinoma.

2.3. Diagnostic procedures and instrumentation
The patients were assessed and counseled pre- and postoperatively by phoniatricians and logopedists to determine and to document the degree of voice and swallowing impairment and improvement, respectively. The examinations included the patient's history, a complete head and neck examination with videolaryngoscopy and videostroboscopy, voice range profile measurements and voice function tests. This protocol corresponds to the recently published guideline for functional assessment of voice pathology elaborated by the Committee on Phoniatrics of the European Laryngological Society [9].

For videolaryngoscopy and stroboscopy, the following devices were used: rigid endoscope 90° Wolf (Vienna/Austria), endostroboscope unit type 5052 Wolf, videocassette recorder SVO 9500 MDP Sony, color video monitor model PVM 1443 MD, CCD endocam 5501 D Wolf. The singing and speaking voice range profiles were measured using the computerized voice range profile software ‘Phonomat’ by Homoth (Hamburg/Germany). For the singing voice, selected parameters were calculated: the voice range from the lowest to the highest tone (in semitones) and the sound pressure levels (SPL) of nine selected frequencies (g, a, h, c1, e1, g1, a1, c2, e2, g2) for the soft and the loud singing voices. Regarding the speaking voice, the SPL and fundamental frequency (F0) of habitual speaking voice, and shouting voice, respectively, as well as the dynamic range as the difference of the SPL-values of shouting and habitual speaking voices were measured and analyzed. The perceptual judgment of the voice sound using the standard RBH-method (R, roughness; B, breathiness; H, hoarseness), measurements of the s/z-ratio and the maximum phonation time /a:/, digital voice recordings and voice range profile (VRP) measurements were applied.

The parameters roughness, breathiness and hoarseness were rated on a four-point severity scale (0=normal, 1=mild, 2=moderate and 3=severe). The maximum phonation time of sustained /s:/, /z:/ and /a:/ were obtained from three trials following deep inspiration. The s/z-ratio was calculated as the ratio of the maximum phonation time of sustained /s:/ divided through the maximum phonation time of /z:/. In addition, the voice dysfunction index (VDI) as a combination parameter was calculated from the grade of hoarseness, impairment of vocal communication skills, maximum phonation time /a:/, intensity, and frequency range in order to assess the global vocal abilities [10]. Patients with a history of aspiration underwent additional videofluoroscopy of swallowing.

2.4. Surgical procedure of external medialization thyroplasty
The technique used for medialization of the vocal folds has been previously reported by Friedrich [7]. Thyroplasty was applied in all patients on the left side. In women, the implant with 13 mm length (Fig. 1 ) was used, and in men the 15 mm was used. Fig. 2 shows the main surgical steps. The perceptual evaluation of voice sound was sufficient to assess intraoperatively the best implant position. To avoid migration of the prosthetic material, the implant was sewed to the thyroid cartilage using monophilic non-absorbable thread. All patients got wound drainage for approximately 2 days and stayed in hospital after surgery for about 3 days. Patients were examined with regard to function for the first time 1 week after surgery and then in regular follow-ups.

View larger version (58K): [in this window] [in a new window]   Fig. 1. Titanium vocal fold medialization implant (TVFMI®).

View larger version (73K): [in this window] [in a new window]   Fig. 2. Surgical procedure: (a) marking of anatomical landmarks (from right to left: superior laryngeal incisura, planned skin cut, inferior margin of thyroid cartilage, jugular fossa); (b) drilling of a window into the thyroid cartilage; (c) positioning of the implant after mobilization of the endolaryngeal tissue.

	3. Results

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
3.1. Videolaryngoscopy/videostroboscopy
Prior to thryroplasty, all patients revealed a left-sided recurrent nerve paralysis. Twelve subjects showed a paramedian vocal fold fixation and two a lateral one. The stroboscopic judging of the glottal closure was performed on the basis of the rating protocol by Södersten and Lindestad [11]. Preoperatively, twelve patients showed an incomplete glottal closure all along the vocal folds, two patients had an incomplete closure of the posterior two-thirds of the folds. Following thyroplasty, a complete closure could be observed in six subjects during the closed phase of an oscillation cycle. Three patients had an almost complete closure with a minor gap in the cartilaginous part. A triangular incomplete closure reaching anterior to the vocal processes was found in four patients, whereas a triangular incomplete closure of the posterior third of the folds could be observed in only one case. In all patients, the vibration patterns of the vocal folds were improved due to the improved glottal closure.

3.2. General patients' rating
All patients were asked about subjective alterations of voice, swallowing and breathing functions in the course of the follow-up examination. They reported on an improved voice quality, better breathing control and reduced dyspnea during phonation. Furthermore, they mentioned a recovered laughing and coughing function after thyroplasty.

3.3. Perceptual evaluation of the voice sound according to the RBH-scheme
As outlined in Table 2, the perceptual evaluation of voice sound showed a significantly reduced level of the parameters roughness, breathiness and hoarseness.

3.5. Voice range profile measurements
The results of the selected singing and speaking voice parameters are compiled separately in Table 2. The range of the singing voice showed a preoperative mean value of 18.3 semitones and a significantly increased mean of 21.7 semitones postoperatively (P=0.011). Fig. 3 reflects the results of SPL for soft and loud singing at seven selected frequencies. It is of great interest that in particular, the number of patients who are able to produce the selected frequencies increased. While the SPL for the soft singing voice were not influenced by medialization thyroplasty, the postoperative mean SPL-values of the loud singing voice increased significantly for almost all frequencies. Thus, all patients could benefit from the external vocal fold medialization thyroplasty in terms of dynamic range of the singing voice.

View larger version (22K): [in this window] [in a new window]   Fig. 3. Singing voice range profile measurements with the curves of soft and loud singing voices.

3.6. Voice dysfunction index
The score of this complex parameter confirms the postoperative improvement of voice function. The VDI decreased significantly (P=0.001) from a mean of 2.6 to 1.4.

3.7. Swallowing function/videofluoroscopy
All patients reported on a subjective improvement of swallowing function. Only one patient mentioned occasional aspiration with liquids after medialization thyroplasty. Videofluoroscopic examinations were performed preoperatively in 10 of the 12 patients, who complained aspiration with coughing. The radiographic examination of swallowing confirmed the suspected aspiration only in four patients. For this reason, a postoperative follow-up was carried out only in selected cases; in three patients no aspiration could be observed radiographically.

	4. Discussion

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
In this study, the clinical outcome of external vocal fold medialization thyroplasty with the recently developed, standardized titanium implant according to Friedrich is demonstrated. In all patients, this procedure was necessary because of unilateral vocal fold paralysis caused by recurrent laryngeal nerve injuries during cardiothoracic surgery. The patients complained not only about voice problems, but also of swallowing difficulties and impairment of the breathing function. The anatomy of the left recurrent laryngeal nerve, passing around the aortic arch, makes it vulnerable to injury during selected left-sided cardiothoracic interventions. The nerve may be stretched during the opening of the mediastinal pleura and is exposed to injury during dissection, for instance, during the extended mediastinal lymphadenectomy of the aortopulmonary window [13]. In cases of advanced tumor stages and infiltrated lymph nodes, the nerve has to be resected intentionally.

Since Isshiki introduced the basic technique of thyroplasty more than 25 years ago [14], medialization thyroplasty is a frequently used procedure for management of incomplete glottal closure. Several modifications of the Isshiki's thyroplasty type I were suggested to optimize the intraoperative manufacturing time, the positioning of the implant and the implant material itself (autologous cartilage, silastic, hydroxilapatite, vitalium, polytetrafluoroethylene). The adjustable preformed titanium vocal fold medialization implant ensures an uncomplicated and time saving application and a sufficiently rigid fixation in the thyroid cartilage [7]. It offers the advantage that the length of the posterior shank can be adjusted thus allowing an individual adaptation. Titanium, as a non-ferromagnetic material, does not interfere with magnetic resonance imaging or computed tomography [15]. Thus, postoperative imaging examinations for oncological follow-up can be carried out. Medialization thyroplasty is now the most widely used laryngeal framework procedure to restore disturbed laryngeal function due to insufficient glottal closure, which causes not only deterioration of voice with reduced vocal efficiency, breathing and coughing problems, the inability of laughing, swallowing difficulties but also an impairment of life quality.

In this series of 14 patients, the medialization thyroplasty was successfully applied to improve these impairments by enhancing glottal closure and vibratory dynamics of the vocal folds since the voice therapy did not show a positive effect. All patients reported normal voice sound without hoarseness prior to cardiothoracic surgery. Thus, an intraoperative injury of the recurrent laryngeal nerve has to be discussed. In ten surgical reports, no details were given on the recurrent laryngeal nerve; in three cases, however, the surgeons explicitly recorded having dissected and thoroughly taken care of the recurrent nerve. In one case, the surgeon had to intentionally sacrifice the nerve due to tumor extension. Definite or suspected causes of the palsy are detailed in Table 1. All anamnestic, perceptual, videostroboscopic, acoustic, and aerodynamic data investigated underline the clinical benefit after external medialization thyroplasty regarding primary goals of this surgical technique: to improve phonation, vocal efficacy and coughing and to decrease subjective swallowing impairment and aspiration. The s/z-ratio, which revealed a significant improvement after vocal fold medialization, was used for evaluation of laryngeal function in patients with pathological vital capacities after lobectomy and pneumonectomy. As to the swallowing function, we observed a convincing improvement in the degree of aspiration and swallowing impairments in most of the patients. These data were gathered for all patients by anamnestic data, the videofluoroscopy objectified the aspiration only in a few cases. It is generally accepted that the probability of aspiration is increased in patients with unilateral vocal fold movement disorders [16,17]. With the improved glottal closure after vocal fold medialization, we assume a positive effect on the swallowing impairment and aspiration.

The incidence of vocal fold paralysis after cardiothoracic interventions is relatively high. As reported by Hulscher et al., 22% of the 140 patients suffered from temporary vocal fold paralysis and 4% of permanent one after subtotal esophagectomy [18]. The authors ascertained a higher percentage of pulmonary complications in the patient group with vocal fold paralysis. Similar results were given by Baba et al., who examined 51 of 141 esophageal cancer patients with vocal fold dysfunction after esophagectomy at the time of discharge from the hospital and 1 year after surgery [3]. The vocal fold dysfunction healed in 21 patients spontaneously, while it persisted in 30 patients.

Walterbusch et al. found a recurrent laryngeal nerve palsy in six of 14 patients after operations of the distal aortic arch and the proximal descending aorta with an antero-axillary thoracotomy approach [1]. Whereas Yamanda et al. reported on hoarseness in 4% of the patients due to recurrent nerve palsy after primary lung cancer surgery [2], Filaire et al. found a vocal fold dysfunction in 31% of patients after left lung resection for cancer with a high rate of postoperative respiratory, pulmonary and cardiac complications [19].

Although some authors suggest otolaryngological examinations only in patients with postoperative hoarseness because of a relatively small number of clinically mute recurrent laryngeal nerve palsy [20,21], we recommend a routine otolaryngological vocal fold check before and after cardiothoracic surgery. This is not only important in view of forensic criteria, but also considering the increased risk of pulmonary complications in patients with vocal fold dysfunction. Vocal fold dysfunction impairs coughing and thereby, increases the risk of pulmonary complications such as pneumonia and atelectasis [5,18,19]. Reintubation and/or tracheotomy may be necessary, leading to prolonged stay at the ICU. Aspiration pneumonia can be life threatening, especially after pneumonectomy and lobectomy. Pneumonia from silent aspiration may occur as a consequence of laryngeal sphincter incompetence in some patients with unilateral recurrent laryngeal nerve paralysis [22]. Périé et al. examined five patients with unilateral recurrent nerve paralysis over a 2-month period postoperatively [13], with one patient presenting silent aspiration and another with symptomatic aspiration.

As suggested by several authors and due to the results presented in this study, a phonosurgical intervention like medialization thyroplasty should be indicated more frequently in patients with unilateral recurrent laryngeal nerve palsy, to improve the postoperative quality of life and to decrease long-term postoperative complications [3,4]. For prognostic reasons, it is of utmost importance to know, whether the recurrent laryngeal nerve was preserved or damaged during operation. In cases of intentional cutting, an external medialization thyroplasty should be performed as soon as possible. If the nerve was preserved, an interval of at least 6 months between cardiothoracic interference and medialization thyroplasty is recommended. During this period, a functional voice and swallowing therapy is indicated. An early detection of vocal fold dysfunction due to recurrent laryngeal nerve damage may prevent any aspiration pneumonia, because adequate treatment (functional logopedic therapy, nasogastric tube feeding, percutaneous esophagogastric tube feeding) can be proposed. Based on our current experience, we recommend applying the medialization thyroplasty as a palliative intervention even in patients with incurable malignant tumors to improve the life quality. The external medialization technique of the vocal fold with the preformed titanium implant, according to Friedrich presents an uncomplicated surgical solution for an insufficient glottal closure preserving the structural integrity of the vocal folds.

In summary, this new implant will ensure a precise and atraumatic medialization of the altered vocal fold with good control of positioning, easy adjustment and excellent postoperative functional results.

	Acknowledgments

 
The project on medialization thyroplasty using the titanium implant according to Friedrich was approved by the Ethic Committee of the Medical Faculty of the University Vienna and of the General Hospital Vienna (No. 085/2000). The authors would like to thank Ao.Univ.Professor Dr M. Kundi for his kind support regarding consulting and execution of the statistical data analysis.

	Footnotes

 
Presented at the 16th Annual Meeting of the European Association for Cardio-thoracic Surgery, Monte Carlo, Monaco, September 22—25, 2002.

	Appendix A. Conference discussion

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 
Dr S. Nazari (Pavia, Italy): I wonder if there are any chances of an infection of that prosthesis, or even a migration through the mucosa into the larynx of this prosthesis?

Dr Denk: We had no major complications in this group of patients, so we did not see a migration of the implant. In a case after thyroid cancer surgery, we had one case of migration of the implant into the larynx.

Dr S. Mattiou (Bologna, Italy): As you know surely, when we decide to operate on this problem, we have to compare the cost and benefits with conservative treatment.

So the first question is, did you try before operation conservative treatment?

Second, as you have pointed out in the beginning of your presentation, these patients may have also not only aspiration but oropharyngeal dysphagia with impairment of the orifice of the glottis. So how did you manage these patients with oropharyngeal dysphagia? I have seen you have done videostroboscopy, so you should be well into the problem.

Dr Denk: Of course, first we try logopedic therapy, but if the patient is too weak to make therapy or to benefit from logopedic therapy, or if we are sure that the nerve was cut, then we early recommend to do surgery. After medialization surgery we also do logopedic therapy so that the patient can profit from this improved anatomical situation. The approach now is going towards an early surgical intervention. We can also perform electromyography of the nerve in order to know whether the function will recover or not.

Regarding the second question about aspiration, of course there are many possible pathophysiologic factors of aspiration. Only if aspiration is due to a reduced laryngeal incompetence caused byan incomplete glottic closure, it can be treated by thyroplasty. But if there are other factors, they cannot be influenced by medialization surgery. If indicated, we routinely perform swallowing therapy after thorough diagnostics by video endoscopic and videofluoroscopic swallowing studies.

Dr J. McGuigan (Belfast, United Kingdom): As somebody who has caused a lot of recurrent laryngeal nerve palsies and a big fan of thyroplasty, I couldn’t get from your presentation what was the mean time from injury to surgery?

And secondly, having seen various forms of thyroplasty under local anesthesia, what is the advantage of the titanium implant over other implants or a new implant?

Dr Denk: The time after cardiothoracic surgery and the medialization procedure was between 2 months and 80 months. So it was very different and varied widely, and now we have the tendency to make the procedure earlier in order to prevent aspiration-related complications if aspiration is due to reduced laryngeal competence caused by incomplete glottal closure.

Dr McGuigan: Why do you use titanium implants?

Dr Denk: We use it because it is a preformed implant, so it can be easily inserted, moreover, it is not very expensive in comparison to other implants and it does not interfere with CT scans – this is especially important in cancer patients.

Mr K. Jeyasingham (Winterbourne Down, United Kingdom): Do you expect you will be taking these implants out, and if so, do you think that it will be easy?

Dr Denk: The implant can be easily removed. Even if the function of the nerve recovers, the titanium vocal fold implant does not hinder the vocal fold movement.

	References

Top Abstract 1. Introduction 2. Material and methods 3. Results 4. Discussion Appendix A. Conference... References

 

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