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Journal Information
Vol. 68. Issue 5.
Pages 274-283 (September - October 2017)
Vol. 68. Issue 5.
Pages 274-283 (September - October 2017)
Original article
DOI: 10.1016/j.otoeng.2017.08.008
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Electromyography-Guided Hyaluronic Acid Injection Laryngoplasty in Early Stage of Unilateral Vocal Fold Paralysis
Laringoplastia de inyección con ácido hialurónico guiada por EMG en etapa precoz de parálisis unilateral de cuerda vocal
Itziar Gotxi-Erezumaa,
Corresponding author

Corresponding author.
, Mónica Ortega-Galánb, Ainhoa Laso-Elguezabala, Gonzalo Prieto Pugaa, Carolina Bullido-Alonsoa, Susana García-Gutiérrezc,d, Ane Anton-Ladislaoc, Enrique Moreno-Alonsoa
a Servicio de Otorrinolaringología, Hospital Galdakao-Usansolo, Vizcaya, Spain
b Servicio de Neurofisiología Clínica, Hospital Galdakao-Usansolo, Vizcaya, Spain
c Unidad de Investigación, Hospital Galdakao-Usansolo, Vizcaya, Spain
d REDISSEC – Red de Investigación en Servicios de Salud en Enfermedades Crónicas, Spain
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Figures (5)
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Tables (3)
Table 1. Analysis Parameters of Laryngeal Function.
Table 2. Characteristics of the 28 Patients who Underwent EMG-Guided HA IL.
Table 3. Comparison of the Parameters That Assess Laryngeal Function Before and After HA Injection in Patients With UPVF.
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Introduction and objective

To assess the effectiveness of electromyography-guided hyaluronic acid injection laryngoplasty in the early stage of unilateral vocal fold paralysis in terms of patient recovery from dysphonia and quality of life.


Between January and December 2014, 28 patients with unilateral vocal fold paralysis underwent electromyography and injection of hyaluronic acid in the thyroarytenoid muscle. We compared the voice handicap index, grade, roughness, breathiness, asthenia, strain scale (GRBAS), videostroboscopic parameters and maximum phonation time assessed before, 15 days and 6 months after the intervention, using the non-parametric Wilcoxon rank test.


Out of the 28 patients, 1 had a haematoma in the injected vocal fold (3.57%) and 6 required second injections. The maximum phonation time of the vowel /e/ increased from 6.07 to 12.14s (15 days post-intervention) and subsequently 12.75 (6 months post-intervention). There was also a significant improvement in the grade, roughness, breathiness, asthenia, strain scale in parameters G, B and A both 15 days and 6 months after the intervention. The voice handicap index score decreased from 58.29 to 37.63 (15 days post-intervention) and 29.64 (6 months post-intervention).


Electromyography-guided hyaluronic injection laryngoplasty in unilateral vocal fold paralysis enables, in the same intervention, neuromuscular assessment and temporary treatment of glottic insufficiency with a low risk of complications and improvement in patient's quality of life. This may reduce the need for subsequent treatments, but further research is required to confirm these findings.

Unilateral vocal cold paralysis
Hyaluronic acid
Introducción y objetivos

Evaluar la efectividad de la laringoplastia de inyección con ácido hialurónico guiada por electromiografía en la etapa precoz de la parálisis unilateral de cuerda vocal en función de la mejoría de la disfonía y de la calidad de vida del paciente.


Se realizó estudio electromiográfico y laringoplastia de inyección con ácido hialurónico a 28 pacientes con parálisis unilateral de cuerda vocal entre diciembre del 2013 y diciembre del 2014. Se analizaron los resultados del cuestionario de índice de incapacidad vocal, escala de GRABS, tiempo máximo de fonación y valoración videoestroboscópica, preintervención, a los 15 días y a los 6 meses, con el Wilcoxon rank test no paramétrico.


De los 28 pacientes, 1 tuvo un hematoma en la cuerda vocal infiltrada (3,57%) y 6 requirieron una segunda infiltración. Los parámetros evaluados muestran una mejoría estadísticamente significativa a los 15 días y 6 meses postinfiltración; el tiempo máximo de fonación aumentó de 6,07 a 12,14 (15 días), 12,75 (6 meses); la escala de GRBAS muestra una mejoría estadísticamente significativa en los parámetros de G, B y A. El valor del índice de incapacidad vocal se redujo de 58,29 a 37,63 (15 días) y 29,64 (6 meses).


La laringoplastia de inyección guiada por electromiografía en la etapa precoz de parálisis unilateral de cuerda vocal proporciona, en un mismo acto, la evaluación neuromuscular y el tratamiento temporal del defecto de cierre glótico con bajo riesgo de complicaciones y mejoría de la calidad de vida del paciente. Podría disminuir la necesidad de tratamientos ulteriores, siendo necesario otro estudio que lo demuestre.

Palabras clave:
Parálisis unilateral de cuerda vocal
Ácido hialurónico
Full Text
Introduction and Objectives

Unilateral paralysis of the vocal folds (UPVF) is a cause of glottic incompetence and presents symptoms such as dysphonia, aspiration and phonasthenia, significantly affecting the patient's performance and quality of life. Traditionally these patients have been managed by observation awaiting spontaneous recovery of vocal fold mobility or compensation, by speech therapy to promote recovery of function.1 Injection laryngoplasty has been introduced recently, using temporary material as another option in the initial management of this disorder, with a view to temporarily reducing glottic insufficiency while awaiting recovery of mobility or compensation.2 This consists of medialisation of the immobile vocal fold, by injecting a resorbable agent into the paraglottic space or the lateral portion of the thyroarytenoid muscle (TA) leaving it in a more favourable position for glottic closure.3–6 It can also improve swallowing in patients who have this problem associated with vocal fold paralysis.7

Since Bruening8 started injecting paraffin into the vocal folds in 1911 to compensate for glottic defect in UPVF, various absorbable or temporary and nonabsorbable or permanent materials have been used.9–11 Resorbable materials have the advantage of being more similar biomechanically to the tissue into which they are injected. Although the temporary effect can be a disadvantage when long-term medialisation is required, it can be advantageous when our objective is a short to midterm result as in the early stages of vocal fold paralysis when the extent of nerve regeneration that will take place and the long-term sequelae are uncertain.12 Injectable materials include autologous fat, calcium hydroxylapatite (Radiesse Voice™), polydimethylsiloxane (PDMS or particle silicones), and historically, polyethylene paste (teflon). Temporary injection materials include bovine gelatine (Gelfoam™, Surgifoam™), collagen-based products (Cymetra, Zyplast, Cosmoplast/Cosmoderm), hyaluronic acid (HA) (Restylane, Hyalaform) and carboxymethylcellulose (Radiesse Voice Gel™).9 Hyaluronic acid has become one of the most-used temporary injection materials. Hertegard et al.17 first introduced HA for vocal fold paralysis in 2002.

Considering that HA is one of the natural components of Reinke's space, it has the advantage that its injection does not induce a local inflammatory response. This means that the viscoelasticity of the superficial lamina propria is maintained and remains stable after injection. Its effect lasts approximately 4–9 months, therefore it has been used principally for the temporary treatment of glottic insufficiency.17 Moreover, there are histological studies that demonstrate connective tissue growth and fibroblast recruitment associated with the injection of this material into the vocal folds, with no concomitant inflammatory reaction.18,19 There are various types of HA on the market. Restylane and Restylane Perlane are used interchangeably in the vocal folds. Restylane Perlane is a non-animal stabilised HA. The gel particles are 1000μm in size. Restylane Perlane was chosen for this study because of its larger-sized particles. Furthermore, the safety and durability has been demonstrated of Restylane injection in the vocal muscle or submucosal connective tissue of the vocal folds.20,21 A study by Lim et al. observed that HA gels remained well preserved inside the vocal folds for a study period of 9 months, although up to 30% of the HA was resorbed.21

UPVF can be due to a lesion affecting motor innervation (paralysis) or infiltration of its musculature or ankylosis of the cricoarytenoid joint (fixation). The most-established indication for laryngeal electromyography (EMG) to date, apart from its therapeutic use to guide botulinum toxin injections, is to diagnose laryngeal immobility. More specifically, it plays a role in the differential diagnosis between mechanical fixation and neurogenic injury and true paralysis of the vocal folds.22–24

The aim of this study was to assess the neuropathic damage in the early stages of UPVF and to prospectively research the results of EMG-guided HA IL. Because the AT muscle is the target of both, laryngeal EMG and IL, this type of procedure will enable us to offer UPVF patients early diagnosis and treatment in a single act and probable improvement of their quality of life. As far as we are aware, there has been no study as yet in our country on EMG-guided injection laryngoplasty.


This was a quasi-experimental, before-and-after design study, which included 28 patients diagnosed with UPVF from hospitals in the Basque Country, who underwent laryngeal EMG in the early stages for diagnostic and therapeutic purposes by simultaneous IL with HA, as an initial protocol for vocal disability caused by the UPVF, in a tertiary hospital between December 2013 and December 2014.

The study was approved by all of the ethics committees of the participating centres. All the patient signed their informed consent to participate in the study before the intervention and all of them underwent the routine examinations of a voice unit: clinical history, subjective evaluation by the patient using the vocal handicap index (VHI) developed by Jacobson et al.,25 perceptual assessment of voice quality using the GRABS scale which was developed by the Japanese society of speech and language therapists,26 aerodynamic assessment by maximum phonation time (MPT) and rigid and flexible endoscopic evaluation with fixed and with videostroboscopic light (Table 1).

Table 1.

Analysis Parameters of Laryngeal Function.

Parameters  Unit or range  Note 
MPT  During phonation of the vowel /e/ 
Grade (G)  0–3GRABS scale for the perceptual voice quality evaluation (Hirano26). Four-point scale, from 0 to 3: “0”=normal, “1”=mild, “2”=moderate, “3”=severe
Roughness (R) 
Asthenia (A) 
Breathiness (B) 
Strain (S) 
VHI  0–120  Developed by Jacobson et al. 

A, asthenia; B, breathiness; G, grade; R, roughness; S, strain; MPT, maximum phonation time; VHI, voice handicap index.

In all the cases of UPVF included in the study, EMG was performed at least 3 or 4 weeks after the onset of symptoms as described in the literature.3 The maximum information was obtained at 3–4 weeks (alterations of conduction together with denervation) and reinnervation phenomena could be seen at 3–4 months, important for establishing a prognosis. The 28 patients who participated in the study underwent this procedure for diagnostic and therapeutic purposes during this early stage. Consequently, the minimum time for performing the procedure was 3 weeks and the maximum 4 months after the neuropathic damage.

All the procedures were performed in the neurophysiology clinic, using the same EMG device (Portable Keypoint-4 Channel Alpine Biomed Aps, Skovlunde, Denmark) in the presence of an ENT specialist and a clinical neurophysiology specialist who undertook the electromyographic recording with a neurophysiology nurse.

In a first stage, we performed the diagnostic laryngeal EMG, after applying a local anaesthetic (EMla) to the skin, 30min before the intervention with the patient in a supine position, and their head in extension. Disposable concentric (bipolar) 26 gauge, 50mm needles were used for the measurements, and Bo-Ject® disposable hollow monopolar 23 gauge, 75mm needles for the injections.

Both AT muscles were punctured in the EMG assessment to evaluate the recurrent laryngeal nerve and both cricothyroid muscles to assess the superior laryngeal nerve using the technique described in the literature27 (Fig. 1). The electromyographic parameters evaluated were:

  • -

    Presence of resting electrical activity: fibrillations and positive waves, complex repetitive discharges, myotonic discharges.

  • -

    Visual assessment or measurement, as necessary, of the MUAP (motor unit action potentials) and their parameters (amplitude, duration, morphology).

  • -

    The motor unit recruitment pattern at maximal effort.

  • -

    Existence of synkinesis.

Figure 1.

(A) In the EMG pattern we observed fibrillations in the study of the AT muscle of the paralysed vocal fold. (B) EMG-guided HA injection procedure.


In a second stage, the AT muscle of the paralysed vocal fold was injected with 2ml HA (Restylane Perlane; Q-Med, Uppsala, Sweden), guided by EMG. A nasofibroscopic examination was performed at the end of the procedure to assess the final result.

In order to evaluate laryngeal function, the abovementioned parameters were assessed preoperatively and at 15 days and 6 months postoperatively. The comparisons of the data before and after treatment were analysed with the nonparametric Wilcoxon rank test using SAS v9.4 software (SAS Institute, Inc., Cary, NC). The graphs were made using R v 3.0.0. software and the statistical significance defined as P<.05.


The characteristics of the 28 patients who took part in the study are summarised in Table 2. The mean age of the patients was 60.66, 8 were male and 20 female. The most common cause was UPVC after thyroid surgery (46.43%), followed by idiopathic cause (25%), vascular surgery (14.29%), oesophageal surgery (7.14%) and cervical tumour (7.14%). Six patients presented a right-sided UPVC and 22 a left-sided UPVC. The time from onset of symptoms until the EMG and HA injection was 4 weeks to 4 months with a mean of 69 days (29–129). The recurrent laryngeal nerve was affected in 28 patients who underwent EMG and the superior laryngeal nerve was affected in 5 of the 28 patients. Five patients had a neuroapraxic lesion, 22 patients had a partial axonotmesis and one patient had an axonotmesis over an underlying chronic neuropathy. Of the 5 patients with a neuroapraxia, 4 regained vocal fold mobility and one did not. Of the 22 patients with partial axonotmesis, 6 recovered mobility and 16 did not. The patient with chronic neuropathy and acute axonotmesis did not recover vocal fold mobility, one patient underwent thyroid surgery and given the EMG result, it is probable that he had a prior lesion due to compression added to which was an acute lesion secondary to the surgical act. Twenty-seven patients had no complication (96.43%) and one had a haematoma in the infiltrated vocal fold (3.57%). Twenty-two patients did not require a second injection and 6 required a second injection 3 months after the first. In 4 of these patients the recurrent laryngeal nerve as well as the superior laryngeal nerve were affected, the consequence was a more lateral position of the vocal fold and this justified a second injection.

Table 2.

Characteristics of the 28 Patients who Underwent EMG-Guided HA IL.

No.  Age  Sex  Cause of UPVC  Diagnosis  Time of EMG-guided HA IL  EMG diagnosis  Laryngeal or recurrent nerve affected  Superior laryngeal nerve affected  Complication  Recovery of mobility  Need for a 2nd HA injection 
71  Thyroid surgery  PICV  65  Partial axonotmesis  Yes  No  No  No  Yes 
47  Cardiovascular surgery  PDCV  73  Partial axonotmesis  Yes  No  No  No  No 
51  Thyroid surgery  PICV  79  Partial axonotmesis  Yes  No  No  No  No 
53  Thyroid surgery  PDCV  59  Partial axonotmesis  Yes  No  No  No  No 
56  Oesophageal surgery  PDCV  89  Partial axonotmesis  Yes  Yes  No  No  Yes 
50  Neck tumour  PDCV  49  Partial axonotmesis  Yes  Yes  No  No  No 
50  Idiopathic  PICV  99  Neuroapraxia  Yes  No  No  No  No 
79  Thyroid surgery  PICV  29  Partial axonotmesis  Yes  No  Haematoma  No  Yes 
76  Neck tumour  PICV  45  Partial axonotmesis  Yes  No  No  No  Yes 
10  42  Idiopathic  PICV  93  Partial axonotmesis  Yes  No  No  Yes  No 
11  62  Thyroid surgery  PICV  129  Neuroapraxia  Yes  No  No  Yes  No 
12  67  Thyroid surgery  PICV  45  Partial axonotmesis  Yes  No  No  Yes  No 
13  57  Idiopathic  PICV  35  Partial axonotmesis  Yes  No  No  Yes  No 
14  35  Cardiovascular surgery  PICV  46  Partial axonotmesis  Yes  No  No  Yes  No 
15  80  Oesophageal surgery  PICV  69  Partial axonotmesis  Yes  Yes  No  No  Yes 
16  78  Cardiovascular surgery  PICV  69  Partial axonotmesis  Yes  Yes  No  No  No 
17  80  Thyroid surgery  PICV  70  Chronic neuropathy+axonotmesis  Yes  No  No  No  No 
18  77  Idiopathic  PICV  71  Partial axonotmesis  Yes  No  No  No  Yes 
19  67  Idiopathic  PICV  74  Partial axonotmesis  Yes  No  No  No  No 
20  81  Thyroid surgery  PICV  76  Partial axonotmesis  Yes  No  No  No  No 
21  43  Thyroid surgery  PDCV  70  Partial axonotmesis  Yes  No  No  No  No 
22  53  Thyroid surgery  PICV  67  Partial axonotmesis  Yes  No  No  No  No 
23  71  Thyroid surgery  PICV  64  Neuroapraxia  Yes  No  No  Yes  No 
24  57  Idiopathic  PICV  69  Partial axonotmesis  Yes  No  No  No  No 
25  57  Cardiovascular surgery  PDCV  70  Neuroapraxia  Yes  Yes  No  Yes  No 
26  38  Thyroid surgery  PICV  56  Partial axonotmesis  Yes  No  No  Yes  No 
27  51  Idiopathic  PICV  69  Partial axonotmesis  Yes  No  No  Yes  No 
28  40  Thyroid surgery  PICV  103  Neuroapraxia  Yes  No  No  Yes  No 

EMG, electromyography; F, female; HA, hyaluronic acid; IL, injection laryngoplasty; M, male; RPVF, right paralysis of the vocal cord; LPVF, left paralysis of the vocal fold; UPVF, unilateral paralysis of the vocal fold.

Comparisons of the mean (± standard deviation) of each parameter before injection, at 15 days and 6 months, are shown in Table 3, statistically significant improvement can be observed in each of the parameters analysed. MPT /e/ increased by 6.07–12.14 (15 days post-infiltration), 12.75 (6 months post-infiltration) (Fig. 2). The GRABS scale also shows statistically significant improvement (Fig. 3). The VHI score reduced from 58.29 to 37.63 (15 (days) post-injection), 29.64 (6 months post injection) (Fig. 4).

Table 3.

Comparison of the Parameters That Assess Laryngeal Function Before and After HA Injection in Patients With UPVF.

  Base  15 days post injection6 months post injection
  x¯ (sd)  x¯ (sd)  P value  x¯ (sd)  P value 
MPT (s)  6.07 (3.43)  *12.14 (6.66)  <.0001  *12.75 (6.01)  <.0001 
- G  2.18 (0.82)/2 [1.5–3]  *0.96 (0.88)/1 [0–2]  <.0001  *0.89 (0.79)1 [0–1.5]  <.0001 
- R  0.46 (0.58)/0 [0–1]  0.29 (0.66)/0 [0–0]  .2344  0.32 (0.61)/0 [0–0.5]  .2188 
- A  2.29 (0.53)/2 [2–3]  *0.82 (0.86)/1 [0–1]  <.0001  *0.79 (0.83)/1 [0–1]  <.0001 
- B  2.14 (0.80)/2 [1.5–3]  *0.89 (0.83)/1 [0–1]  <.0001  *0.86 (0.76)/1 [0–1]  <.0001 
- S  0.39 (0.50)/0 [0–1]  0.21 (0.42)/0 [0–0]  .0625  0.21 (0.42)/0 [0–0]  .0625 
VHI  58.29 (23.40)  *37.63 (26.55)  <.0001  *29.64 (22.36)  <.0001 

A, asthenia; B, breathiness; G, grade; R, roughness; S, strain; MPT, maximum phonation time; VHI, voice handicap index.

Figure 2.

The MPT at 15 days and 6 months after injection significantly lengthened compared to the MPT prior to the injection.

Figure 3.

In the perceptual voice evaluation, the GRBAS score at 15 days and 6 months after the injection reduced significantly compared to the score before the injection.

Figure 4.

The total VHI score at 15 days and 6 months after the injection reduced significantly compared to before the injection.


EMG-guided HA injection laryngoplasty in the early stage of UPVF enabled us firstly to carry out an EMG study and show a lesion to the recurrent laryngeal nerve in 28 patients, and a combined lesion of the superior laryngeal nerve in 5 of these patients. Likewise, it enabled us to assess the extent of the lesion and to differentiate between a neuroapraxic lesion in 5 of them and an axonotmetic lesion in 22 of the patients with a poorer prognosis for recovery. Secondly, EMG-guided HA injection laryngoplasty was performed, offering the patient a diagnostic and therapeutic procedure at the same time.

Sulica et al.28 undertook a review of current practice in IL using materials. They observe that in the past 5 years in the U.S.A. the techniques in the awake patient have increased rapidly, due to their clinical usefulness, low rate of complications, cost advantage and short duration. They make the following classification: peroral, transthyrohyoid approach, transthyroid cartilage injections.

The transcricothyroid approach is the most frequently used (47%). All the techniques mentioned, were performed on an awake patient, guided by flexible fibroscope, with a combination of topical and local anaesthetic. This includes topical nasal anaesthesia to perform the nasofibroscopy, topical anaesthesia of the pharyngolaryngeal mucosa to prevent the gag reflex, swallowing and cough that is caused when the mucosa is penetrated by the injection needle and local anaesthesia on the skin when the injection is percutaneous as in the transthyrohyoid, transcartilagothyroid and transcricothyroid approaches.28 The disadvantage of the techniques mentioned is that because flexible fibroscopy is required the gag reflex is increased as well as the patient's discomfort. Moreover, the use of topical anaesthesia in the laryngeal mucosa can anaesthetise the larynx to excess and cause excessive salivary secretion which cause the patient discomfort and make injection difficult. In the study by Sulica et al.,28 discomfort caused to the patient was the reason for the greatest number of failures of the injection technique in the awake patient. The advantage of EMG-guided HA injection laryngoplasty compared to these techniques is, that like them, it is undertaken as an outpatient and the patient is awake. However there is no need for flexible fibroscopy, which prevents the gag reflex. Furthermore EMG prevents “blind” puncture and the consequent irritation of the mucosa and secondary cough which can be triggered in transoral, transthyrohyoid, transcartilagothyroid and transcricothyroid injection which is not EMG guided. Likewise, this is a technique with a low risk of complications. It can be performed as a minor procedure. It enables EMG assessment of the neuropathic lesion and temporary medialisation of the paralysed vocal fold. It will enable us to improve dysphonia in patients with UPVF in the early stages, irrespective of the severity of neuropathic damage or how poor the prognosis for recovery of vocal fold mobility.

Another LI technique with material performed on the awake patient uses direct laryngoscopy under general anaesthesia. The advantage of this technique is that it prevents the patient experiencing discomfort and the possibility that they will not tolerate the procedure. The disadvantage compared to the techniques described in the review performed by Sulica et al.28 and compared to EMG-guided IL is that it has a higher morbidity, greater cost and requires more operation time.

As Sulica et al.28 indicate, each technique has different advantages and disadvantages. The choice of injection technique is generally based on the preference of the surgeon.

The optimal time for medialisation of the vocal fold and the best technique to do so are matters of controversy. The factors that contribute to this controversy include the uncertainty with regard to possible recovery of function, and the concern that some procedures might be irreversible.29

There is evidence in recent studies, such as that by Prendes et al.14 and Alghonaim et al.,30 that patients with UPVC who undergo medialisation injection with a temporary material early are less likely to require a definitive procedure than patients who were initially managed by observation or speech and language therapy.6,7,13–16,31 Bhattacharyya et al.32 made a comparison between early and delayed medialisation of the vocal folds in cases of UPVC secondary to chest procedures and found a significantly reduced risk of pneumonia and length of hospital stay for the group who underwent early injection.32 It is also the hypothesis of Friedman et al.16 that during the operation, the implant material creates a better vocal fold position during the time window of synkinetic reinnervation.16,33

Experiments with animals show that synkinetic reinnervation occurs in more than 65% of all cases of paralysis, which is thought to be comparable with that of human beings.34,35

We believe that in the cases where we perform an early IL, synkinetic reinnervation might be effective in permanently maintaining a better positioned and medialised vocal fold, reducing the need for medialisation at a later stage. By contrast, a paralysed vocal fold that has not been medialised at an early stage will assume a more lateral, less favourable position after synkinetic reinnervation, with the consequent increased likelihood of requiring a subsequent, more permanent medialisation procedure. We need to perform further studies with a greater number of patients in order to demonstrate this hypothesis.

We use Restylane Perlane (Fig. 5) in EMG-guided IL, because as this is a technique that we perform on outpatients and in the early stage of UPVC, the material used should be easily injected via a fine needle, with minimal preparation time. It should be biocompatible, biomechanically similar to the component of the vocal folds and of temporary duration.

Figure 5.

The videostroboscopic findings before and after the injection. (A) Before the injection, the patient had a constant glottic closure defect during phonation. (B) After the injection, a significant reduction in the closure defect was observed during phonation.


According to the study by Rosen et al.19 in which they undertook IL with calcium hydroxyapatite, their VHI was approximately 70 before the injection and approximately 40 after the injection. In our study, the VHI reduced from 58.29 to 37.63 15 days after the injection. The mean MPT was 6.07s in our patients before the IL, very similar to the 5.9s reported by Hirano36 in 1989. Fifteen days after IL, the MPT significantly lengthened to more than 12.14s on average. The improvement in the measurements of MPT, GRBAS and VHI demonstrate the usefulness of this technique in improving glottic competence. Therefore we can conclude that this is an effective procedure for early medialisation in UPVC.

We used 2ml of HA in our study, because we observed that the outcomes after the first injections of 1ml were not completely satisfactory in closing the defect. Subsequently we started to use 2ml with much better outcomes. Although according to the literature, in a study by Chen-Chi Wang similar results to ours were observed with injections of 1ml of HA,37 we believe that this might be due to differences in the size of the glottic hiatus of the patients in both studies, which required more material to be injected to achieve appropriate glottis closure in our cases.

Our study has several limitations. Firstly, we had few patients. We intend to maintain follow up of our patients, collect more cases and report the long-term results in the future. Secondly, we only demonstrate in this study that the EMG-guided injection technique is safe for HA, its usefulness would have to be checked with other materials.


EMG-guided HA IL can be considered a safe and effective technique in expert hands in the treatment of UPVC. It is an alternative to IL with filler materials, is performed on outpatients, with a high success rate and low risk of complications, offering the patient neuromuscular assessment and treatment of the glottis closure defect in one procedure. The short-term result is satisfactory; we see its usefulness especially in the early stage of UPVC, since its durability will be limited over time, from 3 to 9 months. However, the long-term results and the application of other injectable materials using the technique require further research. According to the literature, we believe that it might reduce the need for subsequent treatments at a later stage, because it enables the vocal fold to assume a more appropriate position during the time window of synkinetic reinnervation.20,32,33 A further research study in the future is required to demonstrate this theory.

Conflict of Interests

The authors have no conflict of interests to declare.

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Please cite this article as: Gotxi-Erezuma I, Ortega-Galán M, Laso-Elguezabal A, Prieto Puga G, Bullido-Alonso C, García-Gutiérrez S, et al. Laringoplastia de inyección con ácido hialurónico guiada por EMG en etapa precoz de parálisis unilateral de cuerda vocal. Acta Otorrinolaringol Esp. 2017;68:274–283.

Copyright © 2017. Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello
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