Effects of Voice Therapy in Early Onset Unilateral Vocal Fold Paralysis in Our Tertiaty Care Centre

Abstract

Unilateral vocal cord paralysis presents with dysphonia, shortness of breath and swallowing difficulty and occurs secondary to damage to the recurrent laryngeal nerve by causes such as viral infection, iatrogenic, trauma and idiopathic. The objective of this study was to study the efficacy of early voice therapy in the management of patients with unilateral vocal fold paralysis. Total 116 patients in previous two years were included in this retrospective study suffering from unilateral vocal fold paralysis. They were subjected to a protocol of voice evaluation including Voice handicap index, Maximum phonation time and S/Z ratio. Patients were also examined using Hopkins Examination. All patients included received voice therapy for 6-month duration in 24 sessions. Patients who had started voice therapy early during their symptoms within few days or 1 to 2 weeks had better outcomes regarding Voice handicap index, Maximum phonation time and S/Z ratio than patients who had started voice therapy at 1 to 1.5 month after symptom onset. Early onset voice therapy may enhance the reduction in glottal gap and improvement of voice quality by hindering the development of faulty hyper functional compensatory behaviors; early voice therapy may therefore enhance the patient’s quality of life.

Introduction

Unilateral vocal fold paralysis (UVFP) occurs from a dysfunction of the recurrent laryngeal (branch of vagus) nerve innervating the larynx. It may alter phonation, airway protection, breathing and stabilization of the body core during physical activity. It causes a characteristic breathy voice often accompanied by swallowing disability, a weak cough, and the sensation of shortness of breath. Dysphonia is the main symptom that causes a patient to seek a phoniatrician’s advice. The degree of voice complaints depends on the amount of glottal incompetence and on the type of compensatory behaviours the patient may employ to improve vocal intensity. [1]

When this paralysis is properly evaluated and treated, normal speaking voice is typically restored with compensation of opposite vocal cord. A variety of behavioural and surgical techniques are available, including hard glottal attack, half swallow boom, abdominal breathing, head and neck relaxation, lip and tongue trills, and resonant voice as mainstay of speech therapy. Surgical options for this disorder include medialization of the vocal folds, type I thyroplasty, arytenoid adduction, and nerve reinnervation procedures.

The objective of this study was to evaluate the efficacy of early voice therapy in the management of patients with unilateral vocal fold paralysis and its impact on the quality of life.

Materials and Methods

This was Retrospective study. A total of 116 participants were included in study from 1st January 2019 to 31st December 2020 from our tertiary care center, diagnosed by certified otolaryngologists based on a detailed clinical history and Hopkins Examination. Patients who required further medical treatment or surgical procedure were excluded from this study.

The Inclusion Criteria were the following [2]:

1. Patient having normal hearing with pure tone average (500,1000,2000 and 4000 Hz) less than 25 dB nHL in their better ear and less than 35 dB nHL for participants aged over 60 years.

2. No voice therapy or surgical treatment taken for their vocal cord paralysis.

3. No evidence of other central neurological diseases, such as Parkinson’s disease, Cerebellar disorders, or stroke and no evidence of carcinoma.

4. No signs of other voice disorders, such as vocal nodules or vocal polyp.

5. Able to read a selected passage.

6. Able to understand and speak Gujarati, Hindi or English.

7. No aspiration is there.

8. Unilateral vocal cord palsy due to Viral etiology or other infective etiology, trauma, Iatrogenic or Idiopathic were included.

These criteria were assessed by the first author under guidance of second and third author, an experienced speech pathologist specializing in voice therapy. All participants had been explained about the procedure of voice therapy, role of voice therapy in unilateral vocal cord palsy and importance of starting early voice therapy on outcome. An informed consent had been taken from all participants. Age group was not a bar in this study and patients of all age groups were included in this study from 11 to 80 years. All participants had been given voice therapy in weekly sessions. Total 24 sessions were given to all participants over a period of 6 months. Some participants might have taken treatments for few days in form of Antibiotics, steroids, antivirals or supplementary treatments [3].

The voice therapy protocol includes three stages. Each stage had specific goals and eight sessions, and required homework for every session was completed after treatment. The first stage (1st to 8th weeks) included breathing control, vocal hygiene, relaxation exercise, and the goals were the following: (1) participants could phonate using abdominal breathing support; (2) participants could feel the tension of muscles in the throat, neck, and shoulders, and then relax; and (3) under instruction and demonstration, participants could implement Vocal function exercise (VFE) programs correctly and over 5-s MPT.

The second stage (9th to 16th weeks) included relaxation exercise, VFE programmes, and hard glottal attack. The goals were the following: (1) participants could release the tension in throat, neck, and shoulders by self-monitoring; (2) under cuing, participants could implement VFE programmes by themselves over 10-s MPT; and (3) participants could practice short phrases using hard glottal attack.

The third stage (17th to 24th weeks) focused on VFE programs and Resonant Voice therapy (RVT), and the goals were the following: (1) participants could practice VFE programs using frontal focus and soft voice without cuing; (2) participants could achieve MPT over 15 s; and (3) participants could read a paragraph or make a brief speech using forward resonance and easy phonation.

A comprehensive clinical assessment of the patients was designed to ascertain the etiology of the paralysis, including a thorough medical history, evidence of surgical trauma, or infection. Computed tomography of the skull base, neck, and upper thorax was performed in all patients with UVFP of unknown etiology. Rigid 70 degree endoscope was used for Hopkins Examination. Laryngoscopy was performed at the time of initial diagnosis and after the end of voice therapy.

Participants were instructed to take a deep breath and produce an /a/ as long as possible at a comfortable pitch and loudness level, then they were asked to count the numbers from 1 to 10 and read a Mandarin passage. All speech samples were recorded in an audiotape recorder connected to a directional microphone (dr. speech), which was positioned at an angle of 45 degrees and a distance of 15 cm from the patient’s mouth in a sound-proof room.

Results

Effects of Voice therapy, given in three stages in 24 sessions during 6 months of onset of unilateral vocal fold paralysis, was measured in following parameters:

1. Clinical assessment and physical examination [4]:

Significant changes had been observed in physical, functional and emotional parameters in form of voice fatigue, voice break and breathy voice of patients who had been given voice therapy early after symptoms onset (within 1 to 2 week) than patients who had delayed onset of voice therapy (after 1 month or so). Marked improvements had also been seen in cough and hoarseness of voice.

• (2)Rigid 70 degrees Endoscopic (Hopkins) Examination [4]:

Unilateral vocal fold palsy persisted in almost all patients, but those patients who had been given early onset voice therapy shown markedly improvement in glottis closure than patients with delayed onset voice therapy.

• (3)Maximum phonation time (MPT) [5]:

Mean MPT before voice therapy was 5.59 sec with maximum observed MPT was 8 sec and minimum observed MPT was 3.2 sec. After voice therapy mean MPT observed was 12.14 sec with maximum observed MPT was 14 sec and minimum observed MPT was 8.9 sec. The difference seen in mean MPT before voice therapy and after voice therapy was statistically significant (p value < 0.0001 SD 1.3910550)

• (4)Voice Handicap Index (VHI) [6]:

Mean VHI score before voice therapy was 78.62 with maximum observed VHI score was 113 and minimum observed VHI score was 60. After voice therapy mean VHI score observed was 31.67 with maximum observed VHI score was 40 and minimum observed VHI score was 26. The difference seen in mean VHI score before voice therapy and after voice therapy was statistically significant. (p value < 0.0001 SD 16.858)

• (5)S/Z Ratio [7]:

Mean S/Z Ratio before voice therapy was 2.88 with maximum observed S/Z Ratio was 4 and minimum observed S/Z Ratio was 2.1. After voice therapy mean S/Z Ratio observed was 1.54 with maximum observed S/Z Ratio was 2 and minimum observed S/Z Ratio was 1.4. The difference seen in mean S/Z Ratio before voice therapy and after voice therapy was statistically significant. (p value < 0.0001 SD 0.2286).

These all measurements have been depicted in graphical form in Fig. 1.

Fig. 1.

Effects of voice therapy on unilateral vocal fold paralysis delineated by improvement in 3 voice therapy scores: Voice handicap index, Maximum phonation time and S/Z Ratio

Discussion

Behavioural voice therapy can be helpful in rehabilitating the weak breathy voice quality often associated with vocal fold paralysis. Voice therapy has been found to be effective both as a stand-alone treatment and in conjunction with medical treatments like steroids, antibiotic, antiviral and multivitamins.

The recurrent laryngeal nerve is responsible for both abduction and adduction of the vocal fold. The recurrent laryngeal nerve originates from the vagus nerve, which originates from the brainstem (nucleus ambiguous in the medulla) and travels along the carotid sheath (with the jugular vein and internal carotid artery). The left vagus nerve gives rise to the left recurrent laryngeal nerve as the vagus crosses the arch of the aorta. The left recurrent laryngeal nerve then loops under the ligamentum arteriosum and travels cephalad in the tracheoesophageal groove until it penetrates the larynx to innervate the intrinsic muscles of the larynx. The right vagus nerve delivers the recurrent laryngeal nerve branch at the level of the subclavian artery. The right recurrent laryngeal nerve loops around the subclavian artery and proceeds cephalad to the larynx. Anatomy of right and left recurrent laryngeal nerve have been shown in Fig. 2

Fig. 2.

Depicting anatomy of right and left recurrent laryngeal nerve

The recurrent laryngeal nerve, just prior to its entrance into the larynx, runs deep to the inferior cornu of the thyroid cartilage. For a short section, the nerve is in a space between the cricoid and thyroid cartilage. This is thought to be the space where the nerve is vulnerable to compression from the cuff on an endotracheal tube that is either overinflated or positioned too far cephalad. Because of the circuitous nature of the recurrent laryngeal nerve, multiple disease processes and operative procedures put these important nerves at risk, often resulting in vocal fold paralysis [8].

Patients with unilateral vocal fold paralysis (UVFP) typically present with a fairly sudden onset of breathy, weak, low-pitched dysphonia. In some cases, however, the dysphonia can be high-pitched because of a compensated lengthening of the vocal folds to achieve better glottic closure [8]. Often, UVFP is associated with dysphagia, specifically with liquids, because the resultant glottal incompetence can lead to aspiration. This is especially true if the UVFP is due to a high vagal lesion that results in both a recurrent laryngeal nerve and superior laryngeal nerve palsy. The latter results in significant anaesthesia of the pharynx, contributing to the patient's dysphagia and increased risk for aspiration [9].

Patients with UVFP often report shortness of breath or a feeling of running out of air. In addition, glottal closure is required for individuals to create positive end expiratory pressure (PEEP). Thus, some patients with an immediate postoperative UVFP can experience decreased pulmonary function because of loss of the natural PEEP that occurs with glottal closure. The glottic closure that allows a forceful cough is also compromised and thus a weak, unsuccessful cough is often reported by patients. Phonetory cycle have been shown in Fig. 3. Clinical Picture of unilateral vocal fold palsy has been shown in Figs. 4 and 5.

Fig. 3.

Depicting anatomy of Phonetory cycle

Fig. 4.

Depicting clinical picture of vocal fold palsy (vocal cord in adducted position)

Fig. 5.

Depicting clinical picture of vocal fold palsy (vocal cord in abducted position)

Voice therapy aims to improve glottal closure without causing supraglottic hyperfunction while developing abdominal support for breathing and improving intrinsic muscle strength and agility.

Maximum Phonation Time [5]

This was obtained by having the patient sustain the vowel /a/ for as long as possible on a single breath. The longest of three attempts was calculated as the maximum phonation time.

Voice Handicap Index [6]

These are statements that many people have used to describe their voices and the effects of their voices on their lives. The voice handicap index (VHI) measures the patient’s perception of the impact of his or her voice disorder. The VHI is a useful instrument for quantifying the biopsychosocial impact of a voice disorder, and is able to monitor changes in self-perception of voice handicap after treatment.

S/Z Ratio [7]:

S/Z ratio is a measure of phonation time where maximum sustained time of /S/ is divided by the maximum sustained time of /Z/. To obtain S/Z ratio, following a demonstration the patients were asked to sustain the consonant /S/ for as long as possible after a deep inspiration. The values were obtained on three separate trials. The patients performed the same task during production of consonant /Z/ on three separate trials. S/Z ratio was calculated by dividing the maximum duration for which /S/ was sustained by the maximum duration for which /Z/ was sustained.

Some Useful Voice techniques are shown in Table 1:

Table 1.

Some useful voice techniques for unilateral vocal fold palsy

Voice therapy techniques	Description of the technique
Hard glottal	Hard glottal attack consists of having the patient breath in, build air pressure while posturing the vowel without letting the air out, and then release the vowel
Pushing	Demonstrate pushing method by raising the patient’s fist to about shoulder height, and then pushing his arms down suddenly in a rapid uninterrupted motion, have the patient push and phonate simultaneously
Half swallow boom	Ask the patient not to swallow completely and say low pitch “boom” rather say boom during the swallow, after two or three attempts, the boom is said in a louder and less breathy voice
Abdominal breathing	After establishment of continuous effortless breathing by patient, instruct the patient to count by increments of 5 to 30; allowing air to be replenished automatically at the end of each sequence. The cycle is increased to increments of 7 through 42 and then to increments of 10 through 50 if the patient can count that far on one breath. The patient soon learns that deep inhalations are not necessary before speaking and that air is automatically replenished during a pause
Apprppriate tone focus	Attempts to place sound in the resonating chambers of the face may give power and tone to the voice, thus relieving laryngeal hyperfunction in case when arytenoids approximation occurs but other adductor muscles are weak with vocal fold bowing or glottal chink with harsh low pitched or harsh rough voice
Accent method	This technique of voice therapy focuses on developing abdominal breathing patterns, timing expiration with the onset of phonation, and developing optimal breath support throughout phonation together with controlling the speech, duration, loudness, and intonation of the speaking voice
Lip and tongue trill	The tongue or lips acting like a valve create pressure differences between the outside air and the cavity behind the constriction, creating oscillatory changes of air pressure and air volume velocity. Subglottal air pressures during the production of trills may be greater than normal phonation, thus creating a greater force for vocal fold oscillation
Head, neck and shoulder relaxation	Compensatory vocal and laryngeal behaviours are frequently associated with increased shoulder, neck, and upper back tension, which should be addressed with relaxation exercises to be practiced on a daily basis

Other studies with improvements in parameters are shown in Table 2:

Table 2.

Other studies with more or less same parameters with improvements in score for unilateral vocal fold palsy

Score	MPT(sec)		VHI Score		S/Z Ratio
Name of study	Before voice therapy	After voice therapy	Before voice therapy	After voice therapy	Before voice therapy	After voice therapy
Role of early voice therapy in patients affected by unilateral vocal fold paralysis	6.50 ± 3.22	11.40 ± 3.98
Longitudinal voice outcomes after voice therapy in unilateral vocal fold paralysis	8.3	8.9	24.24	16.09
Efficacy of voice therapy for patients with early unilateral adductor vocal fold paralysis	4.00 ± 0.94	1.90 ± 0.87

Conclusions

This retrospective study established a definitive role of voice therapy in Unilateral vocal fold paralysis. Result of voice therapy in form of clinical improvement and in form of improvement in score would be much better if started as early as possible regardless of age and duration of symptoms and types of treatment given that in all circumstances it would be given on same time period. The protocol of voice therapy has the potential to significantly improve laryngeal physiology, voice quality, voice stability, voice efficiency, and communication function for patients with UVFP at initial stage, and the effects of voice therapy are beyond spontaneous recovery effects.