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Table of Contents
Year : 2020  |  Volume : 22  |  Issue : 2  |  Page : 63-68

The efficacy of botulinum toxin injection on adductor spasmodic dysphonia

1 ENT Department, Faculty of Medicine, Sohag University, Egypt
2 ENT Department, Faculty of Medicine, Alexandria University, Alexandria, Egypt

Date of Submission12-Apr-2020
Date of Decision06-May-2020
Date of Acceptance10-May-2020
Date of Web Publication30-Dec-2020

Correspondence Address:
Prof. Hatem Ezzeldin
ENT Department, Faculty of Medicine, Suhag University, Sohag
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/SJOH.SJOH_11_20

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Background: Adductor spasmodic dysphonia (ASD) is a voice disorder characterized by strained, stuttering-like voice (involuntary disruptions of voice). Botulinum toxin (BT) injection of the vocal folds (VFs) is the treatment of choice, however, the doses and method of injection are variable. Objectives: The aim of this study is to assess the effect of BT injection on the voices of the patients having ASD. Patients and Methods: Twelve patients with ASD treated bilaterally with VF BT injection in the office under local anesthesia. Each patient evaluated by laryngoscopic examination, acoustic analysis, and voice handicap index. Results: All patients improved markedly regarding laryngoscopic, acoustic, and self-assessment parameters. Conclusion: BT can be used effectively for the treatment of ASD and improving phonatory (voice) and quality of patients' life.

Keywords: Acoustic analysis, botulinum toxin, spasmodic dysphonia

How to cite this article:
Ezzeldin H, Youssef G. The efficacy of botulinum toxin injection on adductor spasmodic dysphonia. Saudi J Otorhinolaryngol Head Neck Surg 2020;22:63-8

How to cite this URL:
Ezzeldin H, Youssef G. The efficacy of botulinum toxin injection on adductor spasmodic dysphonia. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2020 [cited 2022 Dec 4];22:63-8. Available from: https://www.sjohns.org/text.asp?2020/22/2/63/305457

  Introduction Top

Three types of spasmodic dysphonia are recognized, adductor, abductor, and mixed type. ASD is a voice disorder characterized by strained, stuttering-like voice. The disorder results in involuntary movements and inappropriately hyperadduct (close) (ASD). Botulinum toxin (BT) injection of the vocal folds (VFs) is the treatment of choice, however, the doses and method of injection are variable.[1],[2]

The exact etiology of spasmodic dysphonia is still unknown, however, theories have evolved over time, as it is caused by underlying psychological causes to the current opinion which emphasizes a primary neurological cause. As a type of dystonia, spasmodic dysphonia has been characterized as a chronic neurological disorder of central motor processing causing action-induced muscular spasms.[3],[4],[5],[6] The average age of onset of spasmodic dysphonia has been reported at approximately 40 years. The disorder appears to occur more often in females, with familial involvement in approximately 12% of all cases.[2],[6]

The most widely used treatment of ASD is the use of BT (Botox) injection. BT is an exotoxin produced from Clostridium botulinum. It works by blocking the release of acetylcholine from the cholinergic nerve end plates, leading to inactivity of the muscles innervated. The effect of BT among patients with ASD is temporary. Alternative treatment options for ASD include several surgical treatments, such as thyroarytenoid myotomy, thyroplasty, selective laryngeal adductor denervation-reinnervation, laryngeal nerve crush, and recurrent laryngeal nerve resection.[7],[8]

There are numerous techniques for awake laryngeal injection, each with its limitations and technical challenges. These techniques include cricothyroid approach, thyrohyoid approach, and transthyroid approach.[9]

The current study has been conducted in our area to address the use of BT for patients with ASD.

Aim of the study

The aim of this study is to assess the effect of BT injection on the patients having ASD and also to assess the patients' satisfaction after treatment.

  Patients and Methods Top

This study is a consecutive clinical series. It is conducted on 12 patients presented by ASD from December 2017 to January 2020. The patients presented to Voice Clinic, Dubai Hospital, Dubai Health Authority, UAE. The patients were diagnosed with ASD by three well-trained phoniatricians after auditory perceptual assessment for the patients' voices and videolaryngoscopic examination. All patients were treated by BT injection in an outpatient clinic while the patients were awake. Written consent was filled by each patient. Seven patients were injected through cricothyroid approach and five patients were injected through thyrohyoid approach.

Cricothyroid approach

The nose of the patient was anesthetized with lidocaine 2% spray. The subcutaneous tissue overlying the cricothyroid membrane is injected with 1 ml 2% lidocaine. The oral cavity is sprayed with 10% Lidocaine by short nozzle, and then, the supraglottic area of the larynx is sprayed using long nozzle. 2 ml 2% lidocaine is injected in the subglottic area through the cricothyroid membrane, which induces cough and spell of the anesthetic to the undersurface of the VFs. The flexible nasolaryngoscope (KayPENTAX fiber-optic nasolaryngoscope with diameter 3.2 mm) is then passed through the nostril in the inferior meatus and then through the nasopharynx till the laryngeal inlet is seen properly.

BT injection is done bilaterally in the thyroarytenoid muscles in a dose of 2.5 IU for each VF and gradually increased in the consecutive injections to reach the optimal effect and duration of improvement. A hypodermic needle 22G with a 4-cm length is used. The needle passed through cricothyroid membrane in the midline, and then, it is directed upward and laterally by 45° to the undersurface of the VF lateral to the thyroarytenoid muscle. The needle is withdrawn after injection and the procedure completed [Figure 1].
Figure 1: Cricothyroid approach (injection needle seen in the subglottic area)

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Thyrohyoid approach

The laryngeal introducer technique for injection laryngoplasty was developed to improve the way of injection laryngoplasty. According to Clary et al. (2014), we used a curved large-bore needle as a laryngeal introducer through thyrohyoid approach. The injection is carried out by a spinal needle. We used an introducer needle, 4 cm, 18G. The spinal needle 9 cm, 25G (orange), is used [Figure 2]. The nasal cavity, the skin overlying the thyrohyoid membrane, the oral cavity, and the laryngeal mucosa were anesthetized as in cricothyroid approach. The flexible nasolaryngoscope (KayPENTAX fiber-optic nasolaryngoscope with diameter 3.2 mm) is used as described in the former approach. Using a 25G needle on a 3-ml syringe filled with 2% lidocaine, the track from the petiole of the epiglottis to the skin is anesthetized. The laryngeal introducer is then inserted after 2 min through the thyrohyoid membrane and then advanced close to the VFs. Then, 2 ml of 2% lidocaine dripped into the superior surface of the VFs. Once the VFs are anesthetized, the spinal needle is connected to the syringe containing BT. The needle was then advanced gently to the site of injection through the superior surface of the VF into the thyroarytenoid muscle. The needle is removed together with the introducer after injection completed in each VF [Figure 3].
Figure 2: Botox vial, spinal needle inside hypodermic needle

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Figure 3: Thyrohyoid approach (injection needle seen in the supraglottic area)

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Each patient was evaluated using protocol of voice evaluation before injection and 2 weeks after injection. Some patients received multiple botulinum injections and followed up to 1-year duration.

Protocol of voice evaluation includes:

Elementary diagnostic procedures

Comprehensive history taking and otorhinolaryngological examination were done for all patients. The history included age, gender, precipitating and etiological factors, a speech sample including counting and a conversation about the daily activities was recorded and assessed by three phoniatricians. The degree of dysphonia, quality of voice, and voice breaks were assessed auditory by the Modified GRBAS scale[11] and scored on a four-point scale (0 = no dysphonia, 1 = mild, 2 = moderate, and 3 = severe).

Clinical diagnostic aids

Each patient was assessed using a flexible fiber-optic nasolaryngoscope inserted through the nose to evaluate the patient while speaking. The vibratory motion of the VFs was assessed for the degree of glottic gap, symmetry, periodicity, and phase closure.

Additional instrumental measures

Acoustic analysis was carried out in a sound-treated room. A 4-s voice sample of sustained vowel < a > was recorded directly into the Computerized Speech Lab (model 4150; Kay Pentax, Lincoln Park, NJ, USA) software using a 50-Hz sampling rate and 16-bit quantization. The microphone was placed at a distance of 15 cm from the patients' mouth. Participants were asked to phonate at their natural pitch and loudness level after several trials of trainings. This phonation sample was subjected to analysis using Multidimensional Voice Program software (Kay Elemetrics Corp., Lincoln Park, NJ, USA). For objective acoustic analysis, the following outcome measures were extracted and analyzed: mean fundamental frequency in Hz (F0), jitter percentage, shimmer percentage, and noise-to-harmonic ratio (NHR).

Arabic voice handicap index

All patients were asked to complete the Arabic version of a voice handicap index (VHI) questionnaire before injection and 3 months post.[12]

The Arabic VHI is a reliable test applied to the Arabic speaking population. It can help in estimating the degree of voice severity. This self-administered questionnaire consists of thirty questions; the patient responds according to the appropriateness of each item (0 = none to 4 = always). The Arabic VHI is scored from 0 to 120, with the latter representing the maximum perceived disability due to voice difficulties based on the patient response.

Statistical methods

The Statistical Package for the Social Sciences version 11 (SPSS, Inc., Chicago, IL, USA) under Windows was used for data entry and analysis. Descriptive statistics were carried out for continuous variables by mean, standard deviation, and range and for qualitative data by number and percent. For all tests, P < 0.05 was considered statistically significant.

  Results Top

Twelve patients with ASD were selected. All patients underwent office-based injection of BT under local anesthesia. All the patients tolerated the procedure. Patients were four males and eight females with mean age. The demographic data of all patients with ASD are demonstrated in [Table 1].
Table 1: Demographic data of patients with adductor spasmodic dysphonia

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Auditory perceptual assessment of the patients' voices

Using the modified Grade, Roughness, Breathiness, Asthenia, and Strain scale and voice breaks, measures before and 2 weeks after injection of BT in patients with ASD showed significant statistical differences regarding degree of dysphonia, voice breaks, and strained correlates, P < 0.05 [Table 2].
Table 2: Comparison of the degree of Grade, Roughness, Breathiness, Asthenia, and Strain scale, stroboscopic findings, acoustic measures, and voice handicap index preinjection and 2 weeks postinjection of botulinum toxin

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Laryngovideostroboscope findings

A comparison of laryngovideostroboscope (LVS) findings preinjection and 2 weeks postinjection of BT showed significant differences regarding glottal closure and degree of hyperadduction. There was a decreased adduction force in the postinjection group manifested by the presence of slight glottal gap. Furthermore, there were significant differences as regards mucosal waves and amplitude, and both parameters were reduced in the postinjection group [Table 2].

Acoustic analysis of voice

A comparison of mean jitter percentage, shimmer percentage, and NHR preinjection and 2 weeks postinjection of BT in patients with ASD showed significant differences regarding jitter percentage, shimmer percentage, and NHR [Table 2].

Voice handicap index

A comparison of VHI scores preinjection and 2 weeks postinjection of BT injection in ASD showed significant differences in lower scores in all patients [Table 2].

  Discussion Top

In the current study, 12 patients diagnosed with ASD are injected with BT (Botox) under local anesthesia in the outpatient clinic under visualization of the VFs with the nasolaryngoscope. Seven patients are successively injected through cricothyroid approach. Five patients are injected through thyrohyoid approach using the laryngeal introducer technique due to difficult visualization of the undersurface of the VFs. All the procedures are done successively by injecting 2.5 IU in the thyroarytenoid muscle bilaterally.

Four patients presented with mild choking for fluids during the 1st week postinjection, and the condition improved gradually during the 2nd week. Those patients were examined by fiber-optic nasolaryngoscopy to rule out the occurrence of VF immobility. All patients showed bilateral freely mobile VFs with slight glottal gap.

Bielamowicz et al. (2001) mentioned that there are different injection techniques that may be utilized, including percutaneous electromyographic-guided and nasolaryngoscopic-guided methods with the same results after injection.

In the past decade, vocal fold injection (VFI) has re-emerged as a valuable treatment modality for a variety of laryngeal disorders. The increasing capabilities of endoscopic technology have increased the number of available approaches and precision of injection delivery.[14]

VFI in the awake setting has the distinct advantages of avoiding limitations of difficult exposure and avoiding general anesthesia with its inherent risks and increased cost.[15]

The laryngeal introducer technique is a novel way of performing awake laryngeal injections. It provides a high rate of success, the ability to be consistently performed by inexperienced clinicians, and is well tolerated by patients. The laryngeal introducer technique could be safely performed on a wide variety of patients with a high rate of success, without complication. Patients had good tolerance of the procedure.[10]

In the current study, we injected 2.5 IU BT bilaterally. The dose increased gradually in the following injections according to the patient response. The mean duration of improvement after injection was 85–87 days.

BT is administered either unilaterally or bilaterally depending on patient response.[13],[16],[17] Brin et al. (2001) reported results from a double-blind, placebo-controlled study investigating the effectiveness of unilateral and bilateral injections of varying dose levels for treating spasmodic dystonia. The 2.5-unit bilateral group recorded the longest duration of benefit.

Bielamowicz et al. (2001) studied two different injection techniques for treating abductor spasmodic dysphonia with a blinded randomized crossover treatment design. Patients were randomly assigned to initially receive either an endoscopic-guided injection or a percutaneous injection, and blinded observers measured or rated visual and acoustic recordings of laryngeal function. Measurements included tally of spasmodic dysphonia symptoms, symptom severity rating, improvement comparison of pre- to postinjection, and tally of voice breaks. The patients also provided ratings of degree of symptom change from pre- to postinjection. They concluded that injection type was not a significant factor (average decrease was from 10 to 8 breathy breaks). Furthermore, Bielamowicz et al. (2000) found no difference between the unilateral and bilateral VFIs with BT in patients with ASD at 2 weeks postinjection.

In our study, assessment of patients was done in 2-week interval after injection as authors (Bielamowicz et al., 2000; Brin et al., 2001; and Schuering et al., 2020) found that it is reliable to assess the patients before and after 2 weeks.

Auditory perceptual assessment of the patients' voices

In the current, all patients showed a significant improvement regarding degree of dysphonia, voice breaks, and strained correlates. BT works by blocking the release of acetylcholine from the cholinergic nerve end plates leading to paresis of the thyroarytenoid muscles and relieve of hyperadducted muscles thus improving the patients voices.

Acoustic events were identified and included the number of phonatory breaks, frequency shifts, and aperiodic segments. Results indicated that those with ASD produced more aberrant acoustic events than the controls. Aperiodicity was the predominant acoustic event produced during the reading, followed by frequency shifts and phonatory breaks.[16],[17]

Laryngovideostroboscope findings

A comparison of LVS findings preinjection and 2 weeks postinjection with BT showed a significant change in glottic closure before and after injection. The hyperadducted VFs improved markedly after BT injection, and slight glottal gap could be seen in most of the patients. This can be explained that Botox injection does not affect the gross mobility of the VFs, but rather, it decreases the tone of the vocalis muscles. Furthermore, there was an improvement in mucosal waves and amplitude due to decreased spasticity and tension and improved biomechanical properties of the VFs. Furthermore, partial bilateral denervation using Botox resulted in laryngeal function, which appeared to be intermediate between that of tightly squeezed pretreatment status and a breathy voice with incomplete adduction after unilateral nerve block.

Bilateral Botox injections resulted in better glottal closure, fewer instances of VF level differences, and better VF vibrations with phase symmetry, as determined by laryngostroboscopy. Bilateral partial denervation by Botox appeared to be the most physiologic in restoring normal VF vibratory function and airflow.[18]

Acoustic analysis of voice

In the current study, improvement occurred in all correlates of dysphonia (jitter percentage, shimmer percentage, and NHR) measured by acoustic analysis of the patients' voices before and after BT.

Aperiodicity was the predominant acoustic event produced during the reading, followed by frequency shifts and phonatory breaks. Within the ASD group, the number of atypical acoustic events decreased following Botox injection.[19]

Voice handicap index

The Arabic VHI is a self-administered questionnaire. It is reliably applied to the Arabic speaking population, as it can help in estimating the degree of voice severity. All patients showed improvements in the three domains of the test, namely functional, physical, and emotional domains after BT injection.

Patients who had Botox injection had significantly improved voice handicap outcome scores as compared to the control group. Spasmodic dysphonia has a significant impact on patients' perception of quality of life as measured by the VHI. Significant improvements in all three subscale scores and the total score on the VHI occur after treatment with BT.[8],[20]

  Conclusion Top

BT can be used effectively for the treatment of ASD and improving phonatory (voice) and quality of patients' life.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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