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Persistent Dysphonia in Hospitalized COVID-19 Patients

      Summary

      Introduction

      The main objective of this study is to estimate the prevalence of persistent dysphonia in hospitalised COVID-19 patients.

      Methods

      Data were collected from those COVID-19 patients who, during the months of March to April 2020, were hospitalised in ward or intensive care unit at the University Hospital of Fuenlabrada. Patients with dysphonia prior to SARS-CoV-2 were excluded. Informed consent was obtained orally by a telephone call, as well as clinical and epidemiological data. Patients who reported persistent dysphonia were assessed using the Voice Handicap Index 10, the maximum phonation time, the s/z ratio and a fibrolaryngoscope examination. Patients who reported persistent dysphagia were assessed with the Eating Assessment Tool 10.

      Results

      A total of 79 patients were included in the study (48 men and 31 women). 10 ICU patients (25%) and 4 ward patients (10,3%) had dysphonia at least 3 months after hospital discharge, but no association was found between ICU admission and the presence of persistent dysphonia (P = 0.139). Persistent dysphonia in patients admitted to the ICU is associated with persistent dysphagia (P = 0.002), also the age of patients with persistent dysphonia is significantly higher than the age of non-dysphonic patients (P = 0.046). The most frequent exploratory finding was vocal cord paresis/paralysis (60.4%).

      Conclusion

      This is one of the first studies to show that persistence of dysphonia may be a consequence of COVID-19, so further studies are needed to assess the evolution and prognosis of these patients and the possible association of dysphonia with the severity of the disease.

      Key Words

      INTRODUCTION

      COVID-19 is a disease with a broad clinical spectrum, ranging from asymptomatic forms to severe forms leading to severe acute respiratory syndrome. It is estimated that prevalence of asymptomatic forms is 40-45% and they are capable of transmitting the disease.
      • Oran DP
      • Topol EJ
      Prevalence of asymptomatic SARS-CoV-2 infection: a narrative review.
      Most symptomatic cases are mild to moderate.
      • Guan WJ
      • Ni ZY
      • Hu Y
      • et al.
      Clinical characteristics of coronavirus disease 2019 in China.
      ,
      • Wan S
      • Xiang Y
      • Fang W
      • et al.
      Clinical features and treatment of COVID-19 patients in northeast Chongqing.
      One of the most frequent otorhinolaryngological complications of COVID-19 according to Özçelik Korkmaz et al
      • Özçelik Korkmaz M
      • Eğilmez OK
      • Özçelik MA
      • et al.
      Otolaryngological manifestations of hospitalised patients with confirmed COVID-19 infection.
      is dysphonia with a frequency of 19.8%. Dysphonia in relation to COVID-19 has been associated with mechanical ventilation and cough, and a significant association between the severity of dysphonia and dysphagia has been observed.
      • Lechien JR
      • Chiesa-Estomba CM
      • Cabaraux P
      • et al.
      Features of mild-to-moderate COVID-19 patients with dysphonia.
      The main objective of this study is to estimate the prevalence of persistent dysphonia in hospitalised COVID-19 patients. The secondary objectives are to describe the exploratory findings found in patients with persistent dysphonia and to assess the association between the presence of dysphonia and dysphagia.

      METHODS

      This study was approved in November 2020 by the Ethical Committee of the University Hospital of Fuenlabrada. Data were collected from those COVID-19 patients who, during the months of March to April 2020, were hospitalised in ward or intensive care unit (ICU) at the University Hospital of Fuenlabrada. The following inclusion criteria were used: patient ≥18 years of age, PCR-confirmed diagnosis of SARS-CoV-2, ≥3 months after discharge and acceptance of informed consent. Patients with dysphonia prior to SARS-CoV-2 were excluded. The following clinical and epidemiological data were considered: age, sex, smoking, cardiovascular risk factors, duration of admission, orotracheal intubation (OTI) and its duration, tracheotomy and its duration, dysphonia, dysphagia and use of inhaled corticosteroids and angiotensin converting enzyme (ACE) inhibitors. Patients who reported persistent dysphonia were assessed using the Voice Handicap Index (VHI) 10, the maximum phonation time (MPT), the s/z ratio and a fibrolaryngoscope examination. The fibrolaryngoscope examination was performed by three different specialists from the Voice Unit of the Department of Otorhinolaryngology. All recordings were evaluated by the same author to confirm the diagnosis. Glottic insufficiency was assessed by stroboscopy and the s/z ratio values (s/z ratio values greater than 1.4 were considered pathological). Patients who reported persistent dysphagia were assessed with the Eating Assessment Tool (EAT) 10.
      Two samples of patients were obtained, one of those hospitalised in ICU and the other of those hospitalised in ward. To select ward patients, simple random sample was carried out using Excel. Informed consent was obtained orally by a telephone call, as well as clinical and epidemiological data, which were checked using the medical record. ICU and ward samples were paired by age and previous diseases. The sample selection process is depicted in Figure 1. Once anonymised, the data collected were included in a database.
      FIGURE 1
      FIGURE 1Sample selection process. OIC, oral informed consent.
      The statistical analysis was performed using SPSS v27 programme. A descriptive analysis of all variables was carried out using the appropriate statistical tools in each case. Qualitative variables were given as numbers and percentages and quantitative variables as mean and standard deviation or median plus interquartile range. Chi-square test was used for comparing qualitative variables and the Mann-Whitney U-test for comparing qualitative and quantitative variables. In cases where the sample size was not large enough to perform Chi-square, Fisher's exact test or calculation of exact bilateral significance (instead of asymptotic significance) was used. A P value <0.05 was considered statistically significant.

      RESULTS

      A total of 79 patients were included in the study (48 men and 31 women). Male patients were younger than female patients, although no significant differences were found (P = 0.623). No significant differences in age were found between patients admitted to the ICU and those admitted to the ward (P = 0.064).
      The clinical and epidemiological characteristics of patients admitted to the ICU are shown in Table 2. In the group of patients with persistent dysphonia admitted to the ICU (n = 10) the median age was 64.5 years (interquartile range, 58.5-69.25), a higher percentage of women (60%) than men (40%) was observed, the mean duration of admission was 41.30 ± 14.97 days, of which 18.5 days (interquartile range, 13-23.5) were in the ICU; 100% of patients required OTI with a mean duration of 15.70 ± 6.27 days, no patient underwent tracheotomy and the most frequent cardiovascular risk factor was obesity (80%). Persistent dysphonia in patients admitted to the ICU is associated with persistent dysphagia (P = 0.002), also the age of patients with persistent dysphonia is significantly higher than the age of non-dysphonic patients (P = 0.046). There is a higher frequency of persistent dysphonia in patients admitted to the ICU (71.4%) compared to ward patients (28.6%), but no statistically significant association was found between admission to the ICU and persistent dysphonia (P = 0.139) (Table 1).
      TABLE 1Characteristics and Frequency of Acute Dysphonia and Persistent Dysphonia in Hospitalised COVID-19 Patients
      Patients (N = 79)Persistent Dysphonia(n = 14)P valueNo Persistent Dysphonia(n = 65)
      Age64 [54-71]64.5 [58.5-69.25]-63 [53.5-72]
      Gender

      Female

      Male


      31 (39.2%)

      48 (60.8%)


      9 (64.3%)

      5 (35.7%)
      -

      22 (33.8%)

      43 (66.2%)
      BMI (kg/m2)

      18.5-24.9

      25.0-29.9

      ≥30

      Unknown


      11 (13.9%)

      22 (27.8%)

      37 (46.8%)

      9 (11.4%)


      0 (0.0%)

      2 (14.3%)

      10 (71.4%)

      2 (14.3%)
      -

      11 (16.9%)

      20 (30.8%)

      27 (41.5%)

      7 (10.8%)
      Diabetes Mellitus20 (25.3%)3 (21.4%)-17 (26.2%)
      Arterial hypertension43 (54.4%)8 (57.1%)-35 (53.8%)
      Dyslipidaemia41 (51.9%)4 (28.6%)-37 (56.9%)
      Smoking

      Non-smoker

      (Ex-)Smoker


      39 (49.4%)

      40 (50.6%)


      9 (64.3%)

      5 (35.7%)
      -

      30 (46.2%)

      35 (53.8%)
      Pack-year38 [15.25-51.75]34.5 [20.63-81.38]38 [12.75-51.75]
      Duration of admission (days)18 [10-36]32.00 ± 20.01-16 [9.5-35.5]
      ICU

      Days of ICU
      40 (50.6%)

      14.5 [10-23.75]
      10 (71.4%)

      18.5 [13-23.5]
      0.139
      Fisher's exact test. Abbreviation: BMI, Body Mass Index.
      30 (46.2%)

      14 [9.5-24.5]
      Acute dysphonia24 (30.3%)14 (100%)10 (15.4%)
      Acute dysphagia

      Persistent
      8 (10.1%)

      7 (8.9%)
      6 (42.9%)

      6 (42.9%)


      -
      2 (3.1%)

      1 (1.5%)
      Usual treatment

      Inhaled corticosteroids

      ACE inhibitors


      10 (12.7%)

      21 (26.6%)


      2 (14.3%)

      4 (28.6%)


      -

      -


      8 (12.3%)

      17 (26.2%)
      Notes: N (percentage). Mean ± Standard deviation. Median [interquartile range].
      low asterisk Fisher's exact test.Abbreviation: BMI, Body Mass Index.
      TABLE 2Characteristics of Patients Admitted to the ICU
      ICU Patients (N = 40)Persistent Dysphonia (n = 10)P valueNo Persistent Dysphonia (n = 30)
      Age62.5 [52.5-66.75]64.5 [58.5-69.25]0.046
      Mann Whitney U test.
      60 [51.75-66]
      Gender

      Female

      Male


      16 (40.0%)

      24 (60.0%)


      6 (60.0%)

      4 (40.0%)
      0.159
      Fisher's exact test.


      10 (33.3%)

      20 (66.7%)
      BMI (kg/m2)

      18.5-24.9

      25-29.9

      ≥30

      Unknown


      5 (12.5%)

      4 (10.0%)

      26 (65.0%)

      5 (12.5%)


      0 (0.0%)

      1 (10.0%)

      8 (80.0%)

      1 (10.0%)
      0.618
      Chi square test.
      ,
      Calculation of exact bilateral significance instead of asymptotic significance.


      5 (16.7%)

      3 (10.0%)

      18 (60.0%)

      4 (13.3%)
      Diabetes mellitus11 (27.5%)3 (30.0%)1.000
      Fisher's exact test.
      8 (26.7%)
      Arterial hypertension20 (50.0%)6 (60.0%)0.716
      Fisher's exact test.
      14 (46.7%)
      Dyslipidaemia18 (45.0%)2 (20.0%)0.082
      Fisher's exact test.
      16 (53.3%)
      Smoking

      Non-smoker

      (Ex-)Smoker



      23 (57.5%)

      17 (42.5%)


      7 (70.0%)

      3 (30.0%)
      0.471
      Fisher's exact test.


      16 (53.3%)

      14 (46.7%)
      Pack-year40.5 [20-56.88]56.50 ± 50.910.549
      Mann Whitney U test.
      39.63 ± 23.57
      Duration of admission (days)37.85 ± 18.2241.30 ± 14.970.414
      Mann Whitney U test.
      36.70 ± 19.27
      OTI

      Days of OTI
      38 (95.0%)

      12.73 ± 5.85
      10 (100%)

      15.70 ± 6.27
      0.077
      Fisher's exact test.


      0.084
      Mann Whitney U test.
      28 (93.3%)

      11.63 ± 5.39
      Tracheotomy

      Days of tracheotomy
      8 (10.1%)

      12.25 ± 3.20
      0 (0.0%)

      -
      0.338
      Fisher's exact test.


      -
      8 (12.3%)

      12.25 ± 3.20
      Acute dysphonia15 (37.5%)10 (100%)5 (16.7%)
      Acute dysphagia

      Persistent
      7 (17.5%)

      6 (15.0%)
      5 (50.0%)

      5 (50.0%)


      0.002
      Chi square test.
      ,
      Calculation of exact bilateral significance instead of asymptotic significance.
      2 (6.7%)

      1 (3.3%)
      Usual treatment
      • Inhaled corticosteroids
      • ACE inhibitors


      4 (10.0%)

      14 (35.0%)


      0 (0.0%)

      4 (40.0%)


      0.556
      Fisher's exact test.


      0.718
      Fisher's exact test.


      4 (13.3%)

      10 (33.3%)
      Notes: N (percentage). Mean ± Standard deviation. Median [interquartile range].
      low asterisk Fisher's exact test.
      Mann Whitney U test.
      Chi square test.
      § Calculation of exact bilateral significance instead of asymptotic significance.
      The clinical and epidemiological characteristics of patients admitted to the ward are shown in Table 3. In the group of patients with persistent dysphonia admitted to the ward (n = 4) the mean age was 56.75 ± 18.14 years, a higher percentage of women (75%) than men (25%) was observed, the median duration of admission was 7 days (interquartile range, 3-16.25) and the most frequent cardiovascular risk factor were obesity, arterial hypertension and dyslipidaemia (50%).
      TABLE 3Characteristics of Patients Admitted to the Ward
      Ward Patients (N = 39)Persistent Dysphonia (n = 4)P valueNo Persistent Dysphonia (n = 35)
      Age69 [57-76]56.75 ± 18.140.249
      Mann Whitney U test.
      69 [57-76]
      Gender
      • Women
      • Male


      15 (38.5%)

      24 (61.5%)


      3 (75.0%)

      1 (25.0%)
      0.279
      Fisher's exact test.


      12 (34.3%)

      23 (65.7%)
      BMI (kg/m2)
      • 18.5-24.9
      • 25-29.9
      • ≥30
      • Unknown


      6 (15.4%)

      18 (46.1%)

      11 (28.2%)

      4 (10.3%)


      0 (0.0%)

      1 (25.0%)

      2 (50.0%)

      1 (25.0%)
      0.350
      Chi square test.
      ,
      Calculation of exact bilateral significance instead of asymptotic significance.


      6 (17.1%)

      17 (48.6%)

      9 (25.7%)

      3 (8.6%)
      Diabetes Mellitus9 (23.1%)0 (0.0%)0.556
      Fisher's exact test.
      9 (25.7%)
      Arterial hypertension24 (61.5%)2 (50.0%)1.000
      Fisher's exact test.
      21 (60.0%)
      Dyslipidaemia23 (59.0%)2 (50.0%)1.000
      Fisher's exact test.
      21 (60.0%)
      Smoking
      • Non-smoker
      • (Ex-)Smoker


      16 (41.0%)

      23 (59.0%)


      2 (50.0%)

      2 (50.0%)
      1.000
      Fisher's exact test.


      14 (40.0%)

      21 (60.0%)
      Pack-year31 [10.5-51]34.50 ± 19.090.791
      Mann Whitney U test.
      31 [10.25-55.5]
      Duration of admission (days)10 [7-15]7 [3-16.25]0.212
      Mann Whitney U test.
      10 [8-15]
      Acute dysphonia9 (23.1%)4 (100%)-5 (14.3%)
      Acute dysphagia
      • Persistent
      1 (2.6%)

      1 (2.6%)
      1 (25.0%)

      1 (25.0%)
      -

      0.103
      Fisher's exact test.
      0 (0.0%)

      0 (0.0%)
      Usual treatment
      • Inhaled corticosteroids
      • ACE inhibitors


      6 (15.4%)

      7 (17.9%)


      2 (50.0%)

      0 (0.0%)


      0.104
      Fisher's exact test.


      1.000
      Fisher's exact test.


      4 (11.4%)

      7 (20.0%)
      Notes: N (percentage). Mean ± Standard deviation. Median [interquartile range].
      low asterisk Fisher's exact test.
      Chi square test.
      Mann Whitney U test.
      § Calculation of exact bilateral significance instead of asymptotic significance.
      The clinical and epidemiological data and exploratory findings of patients with persistent dysphonia are listed in Tables 1 and 4. The most frequent exploratory finding was vocal cord paresis/paralysis (64.3%), followed by atrophy (28.6%) and granuloma (7.1%), one patient (7.1%) had no lesions on fibrolaryngoscopy; distinguishing between ICU and ward, the most frequent finding in those admitted to ICU was paresis, while in those admitted to ward it was atrophy. The vocal cords were most frequently affected unilaterally (50%). No patient with persistent dysphonia was smoker, but 5 (35.7%) of them were former smokers with a median pack-year of 34.5 (interquartile range, 21-81.38). The MPT values and the s/z ratio show that 28.57% of the patients had glottic insufficiency. The median VHI 10 was 13 (interquartile range, 7.5-26.75). 6 patients (42.9%) had persistent dysphagia with a median EAT-10 of 15.5 (interquartile range, 10-24.5). Male patients were younger than female patients, although no statistically significant differences were found (P = 1.000). No significant differences were found between the age of patients admitted to the ICU and those admitted to the ward (P = 0.733).
      TABLE 4Exploratory Findings in Patients With Persistent Dysphonia
      AgeGenderSmoking (p-y)ICU (days)OTI (days)Tracheotomy (days)Fibrolaryngoscopy FindingsVocal CordMPT (sec)S/ZVHI 10DysphagiaEAT 10Inhaled CorticosteroidsACE Inhibitors
      Patient 148MNoYes (25)Yes (21)NoParesisLeft41.2513Yes14NoYes
      Patient 267MEx (92.5)Yes (35)Yes (26)NoParalysisRight44.2512Yes10NoYes
      Patient 364FNoYes (21)Yes (19)NoParesisRight61.76No-NoYes
      Patient 465FEx (21)Yes (23)Yes (18)NoParesisBilateral3236Yes17NoNo
      Patient 574MNoYes (21)Yes (21)NoParalysisBilateral-
      Treated before the start of this study, so these data are not assessable.
      -
      Treated before the start of this study, so these data are not assessable.
      14No-NoNo
      Patient 662FEx (?)Yes (14)Yes (9)NoParesisRight618No-NoNo
      Patient 764FNoYes (14)Yes (13)NoParesisRight100.925Yes23NoNo
      Patient 863FNoYes (8)Yes (7)NoParesis + Atrophy

      Granuloma
      Right

      Left
      71.1432Yes29NoNo
      Patient 970MNoYes (10)Yes (9)NoNo injuries--
      Treated before the start of this study, so these data are not assessable.
      -
      Treated before the start of this study, so these data are not assessable.
      6No-NoNo
      Patient 1069FNoYes (16)Yes (14)NoParesisLeft7113No-NoYes
      Patient 1168FNoNoNoNoAtrophyBilateral171.064No-YesNo
      Patient 1245FEx (21)NoNoNoAtrophyBilateral115.532No-YesNo
      Patient 1338MNoNoNoNo-
      Did not attend the consultation. Abbreviations: M, male; F, female; Ex, Ex-smoker; ?, unknown; p-y, pack-year.
      -
      Did not attend the consultation. Abbreviations: M, male; F, female; Ex, Ex-smoker; ?, unknown; p-y, pack-year.
      -
      Did not attend the consultation. Abbreviations: M, male; F, female; Ex, Ex-smoker; ?, unknown; p-y, pack-year.
      -
      Did not attend the consultation. Abbreviations: M, male; F, female; Ex, Ex-smoker; ?, unknown; p-y, pack-year.
      14No-NoNo
      Patient 1476FEx (48)NoNoNoAtrophyLeft90.4413Yes10NoNo
      low asterisk Treated before the start of this study, so these data are not assessable.
      Did not attend the consultation.Abbreviations: M, male; F, female; Ex, Ex-smoker; ?, unknown; p-y, pack-year.

      DISCUSSION

      This study shows a prevalence of persistent dysphonia of 25% in hospitalised COVID-19 patients admitted to the ICU and 10.3% in patients admitted to the ward. Reviewing the available literature, there are no studies that assess the persistence of this symptom at least 3 months after hospital discharge. In a previous study by Cantarella et al
      • Cantarella G
      • Aldè M
      • Consonni D
      • et al.
      Prevalence of dysphonia in non hospitalized patients with COVID-19 in lombardy, the Italian epicenter of the pandemic.
      in a sample of non-hospitalised patients, it was observed that in 15% of patients dysphonia lasted more than 1 month.
      The aetiology of dysphonia and its permanence in these patients is unknown, but it may be due to multiple causes. On the one hand, 100% of patients with persistent dysphonia admitted to the ICU underwent OTI, which is a potential cause of airway injury, dysphonia and dysphagia.
      • Hurtado Nazal C
      • Araneda Vilches A
      • Vergara Marín C
      • et al.
      Paralisia de cordas vocais após intubação endotraqueal: uma complicação incomum da anestesia geral [Vocal cord paralysis after endotracheal intubation: an uncommon complication of general anesthesia].
      ,
      • Oliveira ACM
      • Friche AAL
      • Salomão MS
      • et al.
      Predictive factors for oropharyngeal dysphagia after prolonged orotracheal intubation.
      Laryngeal injury is a frequent consequence of OTI and is exacerbated with its duration; one of the most common injuries is vocal cord paralysis,
      • Brodsky MB
      • Levy MJ
      • Jedlanek E
      • et al.
      Laryngeal injury and upper airway symptoms after oral endotracheal intubation with mechanical ventilation during critical care: a systematic review.
      ,
      • Kikura M
      • Suzuki K
      • Itagaki T
      • et al.
      Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation.
      which is usually unilateral and of the left vocal cord due to fixation of the endotracheal tube in the right corner of the mouth.
      • Hurtado Nazal C
      • Araneda Vilches A
      • Vergara Marín C
      • et al.
      Paralisia de cordas vocais após intubação endotraqueal: uma complicação incomum da anestesia geral [Vocal cord paralysis after endotracheal intubation: an uncommon complication of general anesthesia].
      The risk of vocal cord paralysis after OTI increases with age over 50 years, diabetes mellitus and arterial hypertension.
      • Kikura M
      • Suzuki K
      • Itagaki T
      • et al.
      Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation.
      ,
      • Hurtado Nazal C
      • Araneda Vilches A
      • Vergara Marín C
      • et al.
      Paralisia de cordas vocais após intubação endotraqueal: uma complicação incomum da anestesia geral [Vocal cord paralysis after endotracheal intubation: an uncommon complication of general anesthesia].
      The most widely accepted mechanism of paralysis is compression of the recurrent laryngeal nerve.
      • Curros Mata N
      • Alvarado de la Torre S
      • Carballo Fernández J
      • et al.
      Late bilateral vocal cord palsy following endotracheal intubation due to COVID-19 pneumonia.
      On the other hand, in our study no patient with persistent dysphonia underwent tracheotomy. Although there is wide disparity between studies on the benefits of early tracheotomy and the definition of prolonged mechanical ventilation,
      • Añón JM
      • Araujo JB
      • Escuela MP
      • et al.
      Grupo de Trabajo de Insuficiencia Respiratoria Aguda de la SEMICYUC. Traqueotomía percutánea en el paciente ventilado [Percutaneous tracheostomy in the ventilated patient].
      Bishop et al
      • Bishop MJ
      • Hibbard AJ
      • Fink BR
      • et al.
      Laryngeal injury in a dog model of prolonged endotracheal intubation.
      observed in an animal model that laryngeal injury due to OTI reached its maximum severity between days 1 and 7, thereafter there was no relationship with duration. Despite the results of this study, during the COVID-19 pandemic many authors have concurred in the recommendation to delay tracheostomy until at least day 14
      • Delides A
      • Maragoudakis P
      • Nikolopoulos T
      Timing of tracheotomy in intubated patients with COVID-19.
      to reduce the risk of infection of healthcare workers. In our hospital, a late tracheotomy protocol was followed, taking into consideration the recommendations of the majority of guidelines.

      E. Hernández-García, M. Martínez-RuizCoello, A. Navarro-Mediano, et al. Open tracheostomy for critically ill patients with COVID-19. Int J Otolaryngol. 2020, 8861013, doi: 10.1155/2020/8861013.

      The decision to perform a tracheotomy was made by consensus between intensive care professionals, anaesthesiologists and otorhinolaryngologists. This decision was individualised for each patient, taking into consideration whether the weaning objectives were met.

      E. Hernández-García, M. Martínez-RuizCoello, A. Navarro-Mediano, et al. Open tracheostomy for critically ill patients with COVID-19. Int J Otolaryngol. 2020, 8861013, doi: 10.1155/2020/8861013.

      Tracheotomies were performed 17 days on average from the start of OTI and mortality in these patients was lower compared to those not tracheostomised.

      E. Hernández-García, M. Martínez-RuizCoello, A. Navarro-Mediano, et al. Open tracheostomy for critically ill patients with COVID-19. Int J Otolaryngol. 2020, 8861013, doi: 10.1155/2020/8861013.

      These data could explain the high prevalence of persistent dysphonia in ICU patients found in our study, despite we did not find a significant association between dysphonia, OTI and its duration, which could be due to the small sample.
      Another possible aetiology is corditis caused by the presence of SARS-CoV-2 in the larynx. Studies have shown the presence of the ACE-2 receptor in the larynx, including the vocal cords,
      • Descamps G
      • Verset L
      • Trelcat A
      • et al.
      ACE2 protein landscape in the head and neck region: the conundrum of SARS-CoV-2 infection.
      ,
      • Sato T
      • Ueha R
      • Goto T
      • et al.
      Expression of ACE2 and TMPRSS2 proteins in the upper and lower aerodigestive tracts of rats: implications on COVID 19 infections.
      which is the SARS-CoV-2 receptor.
      • Hu B
      • Huang S
      • Yin L.
      The cytokine storm and COVID-19.
      Acute dysphonia as a symptom of COVID-19 may be due to direct entry of SARS-CoV-2 into laryngeal cells, leading to laryngeal and vocal cord inflammation.
      • Lechien JR
      • Chiesa-Estomba CM
      • Cabaraux P
      • et al.
      Features of mild-to-moderate COVID-19 patients with dysphonia.
      However, we have not found signs indicative of corditis in patients with persistent dysphonia. According to Lechien et al,
      • Lechien JR
      • Chiesa-Estomba CM
      • Cabaraux P
      • et al.
      Features of mild-to-moderate COVID-19 patients with dysphonia.
      infection-related dysfunction of the lung and thoracoabdominal musculature could also lead to dysphonia, as the ACE-2 receptor is also expressed in these regions.
      There are reported cases of vagus and glossopharyngeal nerve neuropathy in patients with COVID-19,
      • Paliwal VK
      • Garg RK
      • Gupta A
      • et al.
      Neuromuscular presentations in patients with COVID-19.
      and post-viral vagal neuropathy is postulated as a possible aetiology of dysphonia in these patients,
      • Saniasiaya J
      • Kulasegarah J
      • Narayanan P.
      New-onset dysphonia: a silent manifestation of COVID-19.
      which could explain persistent dysphonia and its association with the permanence of dysphagia in ICU patients, as well as the fibrolaryngoscopic findings. Coronaviruses are neurotropic and can induce neuronal injury mainly in the most severe patients.
      • Curros Mata N
      • Alvarado de la Torre S
      • Carballo Fernández J
      • et al.
      Late bilateral vocal cord palsy following endotracheal intubation due to COVID-19 pneumonia.
      ,
      • Fiani B
      • Covarrubias C
      • Desai A
      • et al.
      A contemporary review of neurological sequelae of COVID-19.
      Three main mechanisms have been proposed to explain the neurological disease in these patients: cardiorespiratory failure and metabolic abnormalities triggered by the infection, direct invasion of the nervous system and an autoimmune response to the virus.
      • Berger JR.
      COVID-19 and the nervous system.
      It appears that the autoimmune response may be due to shared amino acid sequences between SARS-CoV-2 and human antigens, such as heat shock proteins.
      • Lucchese G
      • Flöel A.
      SARS-CoV-2 and Guillain-Barré syndrome: molecular mimicry with human heat shock proteins as potential pathogenic mechanism.
      In addition, the ACE-2 receptor is also present in both central and peripheral nervous system,
      • Fiani B
      • Covarrubias C
      • Desai A
      • et al.
      A contemporary review of neurological sequelae of COVID-19.
      which allows the virus to invade it, mainly via two pathways: retrograde axonal transport and the haematogenous pathway.
      • Paniz-Mondolfi A
      • Bryce C
      • Grimes Z
      • et al.
      Central nervous system involvement by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).
      The most frequent finding on fibrolaryngoscopic examination in patients with persistent dysphonia was paresis and paralysis (60.4%), which could be explained by both mechanical ventilation techniques and the infection itself. In addition to the tests performed in this study, some patients with persistent dysphonia and vocal cord paralysis or paresis underwent laryngeal electromyography where reinnervation potentials were observed, an evidence of possible reversibility of the paresis and paralysis found. In one patient a vocal granuloma was found, a lesion associated with intubation.
      • Kikura M
      • Suzuki K
      • Itagaki T
      • et al.
      Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation.
      Two patients presented bilateral vocal cord atrophy, this lesion may be related to both the infection and the intake of inhaled corticosteroids, due to the local deposition of this drug, which can lead to mucosal atrophy and myopathy of the intrinsic laryngeal muscles.
      • Chmielewska M
      • Akst LM
      Dysphonia associated with the use of inhaled corticosteroids.
      ,
      • Chung KF
      • Caramori G
      • Adcock IM.
      Inhaled corticosteroids as combination therapy with beta-adrenergic agonists in airways disease: present and future.
      A single patient had no lesions on examination, probably due to functional dysphonia (dysregulation of laryngeal muscle activity in the absence of neurological or structural lesions), which is the most common laryngeal pathology that causes dysphonia.
      • Van Houtte E
      • Van Lierde K
      • D'Haeseleer E
      • et al.
      The prevalence of laryngeal pathology in a treatment-seeking population with dysphonia.
      There are also described cases of psychogenic dysphonia due to COVID-19 that could justify it, as it has been shown that viral infection can trigger psychiatric symptoms due to the inflammatory response.
      • Buselli R
      • Corsi M
      • Necciari G
      • et al.
      Sudden and persistent dysphonia within the framework of COVID-19: The case report of a nurse.
      Although there are numerous confounding factors such as OTI or inhaled glucocorticoids which are recognised as possible causes of dysphonia, it is possible that the virus is involved in the pathogenesis of dysphonia in some patients, as the fact that there are two dysphonic patients who have not received any treatment that causes this symptom supports the hypothesis that the virus is capable of producing it by various mechanisms that are not yet well established. Despite few patients present with persistent dysphonia without having received any of these treatments, this may be due to the small sample size. However, the aetiology of dysphonia in these patients is likely to be multifactorial and not due to a single cause.
      There are several limitations present in this study. Firstly, there may be a recall bias, which we tried to correct by completing and cross-checking the data with the medical records. Secondly, some medical records are missing data such as BMI, so these data are considered as missing values. Thirdly, some patients had already been treated and the MPT and s/z ratio were not present in the medical records and could not be performed currently, as they would not be assessable due to the treatment. Fourthly, there may be a survival bias, due to the high lethality of the disease in ICU patients, which may lead to an underestimation of the frequency of dysphonia. Finally, the study design does not allow to distinguish whether the cause of dysphonia is the virus itself or the different treatments such as OTI, inhaled glucocorticoids or tracheostomy, which act as confounding factors.

      CONCLUSION

      Dysphonia at least 3 months after hospital discharge is found in 25% of patients admitted to the ICU and 10.3% of patients admitted to the ward, and correlates with persistence of dysphagia in those admitted to the ICU. The most frequent findings in fibrolaryngoscopy are vocal cord paresis in those admitted to the ICU and vocal cord atrophy in those admitted to the ward, these observations justify the persistence of the symptom. This is one of the first studies to show that persistence of dysphonia may be a consequence of COVID-19, so further studies are needed to assess the evolution and prognosis of these patients and the possible association of dysphonia with the severity of the disease. Studies will also be needed to clarify the aetiology of dysphonia in COVID-19 patients.

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