Monika Jabłońska-Jesionowska, *Lidia Zawadzka-Głos
Diagnostic difficulties in children with iatrogenic vocal cord paralysis in the material of the Department of Pediatric Otolaryngology of the Medical University of Warsaw
Trudności diagnostyczne u dzieci z jatrogennym porażeniem fałdów głosowych w materiale Kliniki Otolaryngologii Dziecięcej Warszawskiego Uniwersytetu Medycznego
Department of Pediatric Otolaryngology, Medical University of Warsaw, Poland
Head of Department: Associate Professor Lidia Zawadzka-Głos, MD, PhD
Streszczenie
Wstęp. Przyczyną porażenia fałdów głosowych u dzieci mogą być wady wrodzone, schorzenia układu nerwowego lub przyczyny jatrogenne. Porażenie może dotyczyć jednego lub obu fałdów. Objawem porażenia obustronnego jest stridor oddechowy o różnym nasileniu, a nawet ostra niewydolność oddechowa. Objawami porażenia jednostronnego są zaburzenia fonacji i połykania, jak również stridor oddechowy związany z częściowym zwężeniem i tak wąskich dróg oddechowych u dzieci. Diagnostyka przyczyn porażenia fałdów głosowych u dzieci jest trudna.
Cel pracy. Celem pracy była analiza przyczyn oraz przydatności zastosowanych metod diagnostycznych u dzieci z jatrogennym porażeniem fałdów głosowych.
Materiał i metody. Dokonano retrospektywnej analizy danych medycznych 20 dzieci z jatrogennym porażeniem fałdów głosowych pozostających pod opieką Kliniki Otolaryngologii Dziecięcej Warszawskiego Uniwersytetu Medycznego w 2017 roku.
Wyniki. Analizie poddano dane medyczne 13 chłopców i 7 dziewczynek w wieku od 1 miesiąca do 10. roku życia; mediana wieku, w którym rozpoznano porażenie fałdów głosowych wynosiła 3 miesiące. U 17 dzieci stwierdzono obustronne porażenie, a u 3 ? jednostronne. Przyczyną porażenia u 7 dzieci był zabieg kardiochirurgiczny, u 1 ? zabieg torakochirurgiczny, u 7 ? przedłużona intubacja, u 3 ? niedotlenienie okołoporodowe oraz u 2? chemioterapia winkrystyną.
Wnioski. Rozpoznanie jatrogennego porażenia fałdów głosowych jest trudne. Zastosowane metody diagnostyczne wymagają wzajemnego uzupełnienia. Badaniem bardzo przydatnym w ocenie ruchomości fałdów głosowych u dziecka jest ultrasonografia (USG) krtani, jest ona jednak niemożliwa do wykonania u pacjentów zaintubowanych. Fiberoskopia w znieczuleniu miejscowym jest badaniem łatwo dostępnym, lecz wykonywana na wąskiej, dziecięcej krtani może spowodować zaburzenia oddychania. USG i fiberoskopię u niemowląt należy uzupełnić direktoskopią, aby wykluczyć wady wrodzone dróg oddechowych mogące dawać podobne objawy. W każdym przypadku należy wykluczyć schorzenia neurologiczne oraz wady genetyczne powodujące porażenie fałdów głosowych.
Summary
Introduction. The causes of vocal cord paralysis in children include congenital malformations, nervous system disorders, and iatrogenic causes. The paralysis may affect one or both cords. The signs of bilateral vocal cord paralysis include respiratory stridor of varying severity, and even acute respiratory failure. The signs and symptoms of unilateral vocal cord paralysis include phonation and swallowing disorders, as well as respiratory stridor associated with partial stenosis of already physiologically narrow airways in children. Diagnosing the cause for vocal cord paralysis in children is difficult.
Aim. The aim of the study was to analyze the causes of iatrogenic vocal cord paralysis, as well as to assess the usefulness of diagnostic methods used in children with iatrogenic vocal chords paralysis.
Material and methods. A retrospective analysis of clinical data of 20 children with iatrogenic vocal cord paralysis under the care of the Department of Pediatric Otolaryngology of the Medical University of Warsaw in 2017 was conducted.
Results. The study group included 13 boys and 7 girls aged from 1 month of age to 10 years of age; median age at the diagnosis was 3 months. In 17 children, bilateral paralysis was diagnosed, and 3 children were diagnosed with unilateral paralysis. The cause of iatrogenic vocal cord paralysis in 7 children was cardiac surgery, in 1 ? thoracic surgery, in 7 ? prolonged intubation, in 3 ? perinatal hypoxia, and in 2 ? vincristine chemotherapy.
Conclusions. The diagnosis of iatrogenic vocal cord paralysis is difficult. The applied diagnostic methods require an integrated interpretation. The larynx ultrasound (US) examination remains very useful in the assessment of the vocal cords mobility in children, however, it is not possible to perform this examination in intubated patients. Fiberoscopy, performed under local anesthesia, is widely available, however, performing it on a narrow larynx of a child may cause respiratory disorders. US and fiberoscopy in infants should be supplemented by direct laryngoscopy in order to exclude congenital airway defects that may have symptoms similar to them. In any case, neurological disorders and genetic defects causing vocal cord paralysis must be excluded.
Introduction
Vocal cord paralysis in children is a common pathology. The causes of vocal cord paralysis in children include congenital malformations, nervous system disorders, and, rarely, iatrogenic causes (1-3). Signs and symptoms of vocal cord paralysis include stridor, dysphonia, and dysphagia (1-3). The paralysis may affect one or both cords. The dominant sign of the bilateral vocal cord paralysis is respiratory stridor of varying degree, and even acute respiratory failure. The signs and symptoms of unilateral vocal cord paralysis include phonation and swallowing disorders, as well as respiratory stridor associated with partial stenosis of already physiologically narrow airways in children (3). Iatrogenic vocal cord paralysis may be caused by damage to the vagal trunk or recurrent laryngeal nerves (1, 4). The most common causes for this include injuries and surgical procedures on the central nervous system, neck, heart, and thorax. The paralysis can also be caused by an injury or hypoxia that had occurred in the perinatal period. The use of vincristine in the treatment of various cancer types may also result in iatrogenic vocal cord paralysis (4, 5). Due to dyspnea caused by the small diameter of children’s airways, which can be life-threatening, vocal cord paralysis requires quick diagnostics, and in many cases, it may also be necessary to ensure airway patency through endotracheal intubation. Dyspnea may also be caused by congenital defects of the respiratory tract, respiratory failure due to pulmonary hypoplasia in premature infants, congenital heart defects, vascular anomalies, and neurological conditions. What further complicates the diagnostic process, the factor that impairs the mobility of vocal cords acts at a very early stage of life. Often, the child’s breathing pattern cannot be observed for a time sufficiently long to pose a diagnosis before intubation. All this delays the diagnosis of iatrogenic vocal cord paralysis. The diagnostics of vocal cord paralysis is multistage and requires the use of complimentary diagnostic methods.
Aim
The aim of the study was to identify the causes of vocal cord paralysis and applied diagnostic methods enabling definitive diagnosis in children with iatrogenic vocal cord paralysis under the care of the Department of Pediatric Otolaryngology of the Medical University of Warsaw.
Material and methods
A retrospective analysis of medical data of 20 children with iatrogenic vocal cord paralysis remaining under the care of the Department of Pediatric Otolaryngology of the Medical University of Warsaw in 2017 was conducted. Clinical signs and symptoms presented by the patients were analyzed and the age at the diagnosis was determined. In the diagnostics, larynx ultrasound (US) and endoscopic examination were used. Being intubated disqualified a patient from US examination. Endoscopy was performed in all the patients.
Results
In 2017, 13 boys and 7 girls with iatrogenic vocal cord paralysis remained under the care of the Department of the Pediatric Otolaryngology of the Medical University of Warsaw. Seventeen children suffered from bilateral vocal cord paralysis, and 3 ? from unilateral paralysis.
The cause of iatrogenic vocal cord paralysis in 7 children was cardiac surgery, in 1 ? thoracic surgery with tracheoesophageal fistula closure, in 7 ? prolonged intubation in the perinatal period, in 3 ? perinatal hypoxia, and in 2 ? vincristine chemotherapy due to acute lymphoblastic leukemia.
The reasons for undertaking diagnostics included respiratory, phonation and feeding disorders. Respiratory disorders were characterized by a stridor of a varying degree, from moderate to severe, with accompanying cyanosis and the activation of accessory respiratory muscles, as well as a decrease of oxygen blood saturation, and even the need for urgent intubation. Phonation disorders included silent crying and weak cough. Dysphagia manifested as, among others, choking and hiccups. All of the above-mentioned signs and symptoms were present in our patients directly after birth or after extubation in cases of patients after cardiac or thoracic surgery having undergone prolonged intubation. Seven children, born prematurely between 24th and 26th week of pregnancy, required urgent intubation due to pulmonary hypoplasia. The children remained intubated for about 2 to 3 months. Four children who had undergone cardiac surgery due to heart failure also required intubation that lasted 2 to 3 weeks. After extubation, they presented stridor, often accompanied by dysphagia.
All children with stridor or phonation disorders that were not intubated during the diagnostic process, i.e. 9 children (45%) underwent larynx ultrasound with the assessment of vocal cords mobility. Limited mobility of vocal cords, vocal cords paralysis, or incomplete opening of the cords were observed. The results of the US examination were verified with fiberoscopy in 2 children (10%) aged 4 and 10 years. These children had undergone vincristine treatment for acute lymphoblastic leukemia. A diagnosis of bilateral vocal cord paralysis was confirmed in them. In the remaining 7 children (35%), due to the severity of stridor and their age being equal to or less than 1 month, direct rigid laryngoscopy under general anesthesia was performed. The examination was performed to exclude comorbid congenital defects of the lower airways that could lead to vocal cord immobilization, thus consisting a potential cause for stridor. In all the patients, the diagnosis of vocal cord paralysis was confirmed: in 4 cases, bilateral paralysis was diagnosed, and in 3 cases, unilateral paralysis was confirmed. At the same time, 4 of these children were diagnosed with congenital laryngomalacia, and 3 were diagnosed with tracheomalacia associated with external pressure on the larynx by vascular anomalies that had been previously corrected. In one child, the site of the closure of tracheoesophageal fistula was visualized.
In 11 intubated children (55%), ultrasonographic examination with the assessment of vocal cords mobility could not be performed due to the presence of the endotracheal tube. After several unsuccessful attempts at extubation, a 0-degree rigid endoscopy without muscle relaxation was performed in these patients. In 7 children, subglottic stenosis grade II to IV according to Myer?Cotton and immobility of vocal cords were observed. The mobility in the cricoarytenoid joint was controlled, and in all the cases, no adhesions were found. In these 7 children, tracheotomy was performed. The diagnosis of vocal cord paralysis was confirmed with larynx ultrasound examination with the assessment of vocal cords mobility and/or laryngeal fiberoscopy under local anesthesia. The remaining 4 children had been intubated due to prior cardiac surgery, in 2 cases due to tetralogy of Fallot, and in 2 cases ? after Norwood procedure due to hypoplastic left heart syndrome. In these children, the attempts at extubation ended with tracheotomy. In direct laryngoscopy, no scarring of the vocal cords and subglottic larynx were found in any of the children. Diagnosis of vocal cord paralysis was delayed and based on the larynx US and fiberoscopy.
In order to exclude congenital defects and disorders of the central nervous system that could lead to vocal cord paralysis through a damage of nuclei or trunk of the vagal nerve in neonates, transfontanelle ultrasound of the brain and, in selected cases, also magnetic resonance imaging of the brain, were performed. In all the cases, neurological disorders have been excluded.
The age of children at the diagnosis of the vocal cord paralysis ranged from 1 month of age to 10 years of age. In 3 patients aged 1 month, the diagnosis of iatrogenic bilateral vocal cord paralysis was made. In these children, perinatal hypoxia was identified as the cause of vocal cord paralysis as a diagnosis of exclusion. All these children were born between 37th and 40th week of normal, uncomplicated pregnancy, and received from 1 to 4 points in the APGAR score. Congenital defects of the central nervous system, respiratory system, as well as other congenital defects and potential reasons for hypoxia other than iatrogenic causes were excluded. Three other children, aged 1 month, were also diagnosed with vocal cord paralysis after having undergone cardiac surgery due to congenital heart defects; 1 child had undergone correction of double aortic arch and suffered from bilateral vocal cord paralysis, and 2 children who had underwent closure of patent ductus arteriosus suffered from unilateral vocal cord paralysis. At the same age, a patient who had undergone thoracic surgery for tracheoesophageal fistula was diagnosed with unilateral vocal cord paralysis. In 7 children born prematurely, vocal cord paralysis was diagnosed between 3 and 4 months of age after the period of prolonged intubation due to pulmonary hypoplasia. The diagnosis was made after several failed attempts at extubation. In 4 children, diagnosis was made between 5 and 6 months of age after completing a stage of cardiosurgical treatment and ensuring cardiac status enabling the attempt at extubation, which failed due to respiratory failure caused by vocal cord paralysis. In two girls aged 4 and 10 years treated with vincristine for acute lymphoblastic leukemia, iatrogenic vocal cord paralysis was diagnosed.
A diagnosis of bilateral vocal cord paralysis was made in 17 children (85%). This group included all 3 children with perinatal hypoxia, 7 children after prolonged intubation in the perinatal period, 5 children having undergone cardiac surgery for congenital heart defects (correction of double aortic arch, surgery for tetralogy of Fallot, Norwood procedure by congenital left heart hypoplasia), and 2 children treated with vincristine due to acute lymphoblastic leukemia. Unilateral vocal cord paralysis was diagnosed in 3 children (15%): 2 patients after cardiac surgery for patent ductus arteriosus, and 1 patient ? after thoracic surgery for tracheoesophageal fistula.
Discussion
Diagnosing the cause of vocal cord paralysis in children is difficult. There is little doubt in a situation when a child with no breathing and phonation problems is subjected to surgery in the neck, heart, or thorax, and presents respiratory stridor or changed voice after the surgery. This, however, is rare in children when compared with adult patients. The primary cause for that is the short observation period before the necessity of surgery for congenital respiratory or vascular defects. In such a case, detecting vocal cord immobility in the larynx ultrasound examination, fiberoscopy or direct laryngoscopy clearly suggests the occurrence of a postoperative complication. In our material, such a situation concerned one child (5%) with tracheoesophageal fistula who had undergone surgical correction in the 1st month of life. Based on the larynx US examination, it was determined that stridor and dysphonia that had occurred after the procedure were associated with the paralysis of the left vocal cord.
Respiratory stridor in children can be associated with congenital larynx defects other than vocal cord paralysis. In 2 children undergoing ligation of patent ductus arteriosus, which is sometimes associated with unilateral vocal cord paralysis (3, 6, 7), stridor had already been present before the surgery, and its cause was tracheomalacia due to the external pressure on the larynx by a vascular anomaly. The diagnosis of unilateral vocal cord paralysis was delayed to the moment of co-occurrence of swallowing disorders and weak crying. In these children, larynx US examination was performed, which confirmed the limited vocal cords mobility. Ultrasound examination allows a reliable assessment of the vocal cords mobility, and is possible due to the soft, cartilaginous tissue of the larynx in children (8, 9). The result of the ultrasound should be confirmed by performing larygeal fiberoscopy under local anesthesia in order to exclude other causes for the vocal cords immobility, e.g. congenital laryngeal glottic webs or adhesions between vocal cords (10, 11). Fiberoscopy allows to assess pathologies of the respiratory tract to the level of vocal cords.
In infants, the examination of choice as a replacement of fiberoscopy is rigid laryngoscopy performed under general anesthesia, enabling to exclude congenital airway defects that could potentially cause stridor (6, 7, 12, 13). This examination allows to assess the airways from the supraglottic region, through glottis, subglottis and trachea, to the tracheal bifurcation. In addition, general anesthesia makes it possible to perform intubation in case of sudden respiratory disorders. The risk of such disorders in children must always be taken into account due to the small laryngeal diameter, as well as coexisting respiratory pathologies.
Often the factor that damages vocal cords is present at the very early stage of life of a child. In cases of breathing disorders characterized by stridor, engaging additional respiratory muscles, cyanosis, and low blood oxygen saturation, endotracheal intubation is the method of choice (1-4). In our material, this was the case in 10 children (50%): 3 with perinatal hypoxia, and 7 born prematurely between the 24th and 26th week of pregnancy. Five children with congenital heart defects also required intubation in the first days of life due to cardiovascular insufficiency. In 3 of those children, no stridor was observed, and in the other 2, the stridor was associated with the anomalies of the large vessels: double aortic arch or right-sided aortic arch, which had compressed the airways.
Because of the endotracheal tube inserted into the airways, and because of general anesthesia, it is difficult to assess vocal cords mobility. In this case, the examination of choice is rigid endoscopy under general anesthesia, without muscle relaxation, performed after the extubation (12, 13). In every case of prolonged intubation, subglottic stenosis and adhesions in the cricoarytenoid joint immobilizing the vocal folds must be excluded (12, 13).
In older children ? in our material, 2 children (10%; 4 and 10 years old) ? larynx ultrasonography and fiberoscopy under local anesthesia, possible even as bedside testing, remain the methods of choice (10, 11). Stridor in these children occurred in the course of vincristine chemotherapy of acute lymphoblastic leukemia. Vincristine is an alkaloid having a cytostatic effect and it can be toxic to the peripheral nervous system. This may lead to damage of the vagus nerve, causing vocal cord paralysis. The paralysis is temporary and subsides after dose reduction or after ending the treatment (14, 15).
Part of the difficulties in diagnosing vocal cord paralysis is caused by the occurrence of the damaging factor at a very early point of life (16). In half of the cases, i.e. 10 children, it was not possible to observe the children prior to intubation because of the sudden nature of the respiratory disorder. The diagnosis of iatrogenic vocal cords paralysis required, apart from observing the immobilization of the cords, the exclusion of congenital defects that may have been responsible for the pathology. In 5 children (25%), the respiratory stridor caused by congenital defects had been present before the cardiac and thoracic surgery, therefore, the diagnosis of vocal cord paralysis was delayed (3, 4).
Conclusions
The diagnosis of iatrogenic vocal cord paralysis is difficult. Every diagnostic examination has its advantages and disadvantages. The ultrasound (US) larynx examination remains very useful in the assessment of the vocal cords mobility in children, however, it is not possible to perform in intubated patients. In infants, the result of the US examination should be analyzed together with the results of the direct laryngoscopy in order to exclude other defects causing stridor and immobilization of the vocal cords. Fiberoscopy, performed under local anesthesia, is widely available, however, performed on a narrow larynx of a child may cause respiratory disorders and does not allow to exclude coexisting defects. In every case, neurological disorders and genetic defects causing vocal cord paralysis must be excluded.
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