- Email: [email protected]
Pediatric video laryngo-stroboscopy
International Journal of Pediatric Otorhinolaryngology (2005) 69, 215—219
www.elsevier.com/locate/ijporl
Pediatric video laryngo-stroboscopy Christopher J. Hartnicka,*, Steven M. Zeitelsb a
Department of Otology and Laryngology, Division of Pediatric Otolaryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114-3914, USA b Department of Surgery, Massachusetts General Hospital, Boston, MA, USA Received 24 July 2004; accepted 29 August 2004
KEYWORDS Laryngoscopy; Stroboscopy; Pediatric hoarseness; Dysphonia; Glottic; Glottis
Summary Objective : Laryngo-stroboscopy remains as the clinical gold standard for assessing properties of the glottal phonatory and valvular function. This includes deficits of closure as well as mucosal wave irregularities secondary to abnormal zones of pliability and symmetry. Per-oral stroboscopy has technical limitations in children due to the size of the telescope and issues of patient compliance. However, flexible laryngoscopy is readily performed in newborns and young children. This paper describes the use of a new trans-nasal, digital flexible laryngoscope, which allows for laryngo-stroboscopy in children. Methods and results : A prospective longitudinal series was done on 25 children ages 19 months—13 years (mean age, 7.0 years) with this new technology. All 25 were successfully examined. Conclusions : New technological advancements in the design of digital flexible endoscopes has allowed for laryngo-stroboscopy, and therefore, provides the potential for expanding the population of children with vocal disorders in whom stroboscopic imaging is possible. Larger studies will be necessary to determine its limitations related to age, development, and disease. As the study of pediatric voice disorders continues to evolve, accurate diagnosis is essential to apply state of the art nonoperative and phonosurgical interventions. Further longitudinal studies are currently underway to continue to refine techniques of pediatric voice assessment and to define limitations of this new technology. # 2004 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
* Corresponding author. Tel.: +1 617 573 4206; fax: +1 617 573 6845. E-mail address: [email protected] (C.J. Hartnick).
Bishop, in 1836, deduced that the mucosa of the vocal fold was the primary site of vibration and that variable tension conferred on it from the underlying muscle determined pitch frequency [1]. Unfortunately, the speed of this vibration was imperceptible
0165-5876/$ — see front matter # 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2004.08.021
216
C.J. Hartnick, S.M. Zeitels
to the human eye. In 1878, Oertel attempted to solve this problem by employing a rotating pinwheel/disk to interrupt a steady beam of light during laryngoscopy to ‘‘slow down’’ the appearance of vibration [2]. Unfortunately, the initial prototype laryngeal stroboscope was conceptually sound but impractical. Effective laryngeal stroboscopy required consistent rotational velocities and this device was dependent on hand-cranking the device. By 1895, Oertel had perfected a usable laryngeal stroboscope with the effective use of electricity to control rotational velocity [3]. Stroboscopy was coupled to laryngoscopy to enhance perceptual assessment of vocal fold vibration, which is otherwise impossible given the typical frequencies of oscillation [4—6]. With technological advances in the 20th century, the ability to find novel means of exploring vocal fold vibration allowed for the landmark studies of Farnsworth at Bell Laboratories in 1938 (reported in 1940) where the motion of the vocal folds were described by the use of high speed cinematography [7]. Farnsworth’s studies, and later Van-den-Berg’s [8], described the inferior to superior opening of the vocal folds in the glottal cycle and thus described a more, complex three dimensional motion. Hirano’s
elegant pathologic studies describing the microlayered structure of the human vocal fold with a oscillating cover on a more rigid body structure gave anatomic understanding to the mechanical properties that were being observed during laryngo-stroboscopy [9]. Because of the perceptual limitations of routine laryngoscopy, rigid, telescopic video laryngo-stroboscopy has become a standard and essential tool for a laryngologist to study phonatory disorders. For the inexperienced, it can be a technically challenging exam to accomplish skillfully and to interpret. Furthermore, it has limitations for patients with a strong gag reflex and for children. This is further complicated by the fact that transoral rigid telescopes provide enhanced optical resolution and many children cannot tolerate transoral rigid endoscopy [10]. This observation was made by Kirstein over a century ago when he explained that transoral mirror laryngoscopy was problematic in children, and therefore, he correctly predicted that transoral direct laryngoscopy would substantially enhance the evaluation of young children with laryngeal problems [11]. ‘‘In all probability autoscopy (direct laryngoscopy) will assume an important role in the examination of children, on an equal footing
Table 1 Description of pediatric population undergoing trans-nasal digital laryngo-stroboscopy Patient
Age
Gender
Presenting diagnosis
Trans-nasal stroboscopy
Diagnosis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
11.00 13.00 9.00 10.00 8.00 1.50 6.00 13.00 6.00 8.00 10.00 6.00 3.00 5.00 4.00 8.00 10.00 9.00 4.00 5.00 3.00 6.00 9.00 4.00 5.00
Female Male Male Male Male Female Male Female Female Male Female Male Male Female Female Female Male Male Female Male Female Female Male Male Male
Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Tracheotomy dependent Dysphonia Tracheotomy dependent Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain JRRP Vocal cord nodules, vocal strain Posterior glottic stenosis Vocal cord cyst Supraglottal, glottal stenosis VCN LPR Vocal cord nodules, vocal strain VCN Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord cysts, vocal strain JRRP Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain
JRRP: juvenile recurrent respiratory papillomatosis; VCN: vocal cord nodules; LPR: laryngopharyngeal reflux.
Pediatric video laryngo-stroboscopy
with laryngoscopy (transoral mirror examination); but in preference to laryngoscopy in very young children. Even infants can be examined with the autoscope (direct laryngoscope) . . ..’’ Many patients, both adults and children, better tolerate flexible laryngoscopy however, the flexible stroboscopic examination is less valuable than with a rigid telescope due to diminished optical resolution. Recently, there has been a report about improvements in flexible laryngoscopes by using digital technology for flexible laryngo-stroboscopy which has allowed for enhanced video laryngo-stroboscopy in adults [12]. Previously, narrow-diameter pediatric flexible laryngoscopes have been incapable of stroboscopy, however, adapting digital technology to narrow-diameter flexible laryngoscopes has allowed for stroboscopy in children. We believe that many diagnostic and therapeutic advancements in adult phonosurgery and phonomedicine have yet to be consistently transferred to the pediatric population and laryngeal stroboscopy is but one example. Towards this end, a prospective trial was done to assess its stroboscopic feasibility and utility of a narrow diameter, flexible digital laryngeal stroboscope in children. Between July 1, 2003 and March 1, 2004, 25 children presenting to an outpatient tertiary care pediatric laryngologic voice clinic underwent transnasal flexible laryngo-stroboscopy as part of their formal voice evaluation. Either the Pentax VNL-1130 (distal tip diameter, 3.8 mm), the Olympus ENF type V (distal tip diameter, 3.9 mm), or an Olympus prototype (distal tip diameter, 3.2 mm) were used. Their mean age was 8.4 years. Table 1 describes this population.
2. Results All 25 children tolerated trans-nasal flexible examination with minimal discomfort. In all cases, identifiable laryngeal anatomy was clearly visualized to
217
facilitate a diagnosis. Since stroboscopy is a subjective assessment tool [13], no attempt was made to treat it as an objective measure of vocal function. Two cases are delineated below to serve as illustrative examples of how stroboscopy was helpful in clinical management. Case 1: A 12-year-old girl had sustained a motor accident with prolonged intubation and the development of subglottal stenosis. She had undergone three CO2 laser procedures and two attempted laryngotracheal reconstructions previously at an outside institution and presented the pediatric voice clinic with a chief compliant of marked dysphonia as well as tracheotomy dependence. She had a hyperactive gag reflex and could not tolerate a per-oral stroboscopy. Close trans-nasal stroboscopic evaluation of her glottis was essential as she had extensive glottal and subglottal stenosis and identification of remaining pliable mucosa was essential to plan a planned endoscopic and open repair to facilitate decannulation while preserving her voice to the greatest extent possible (see Fig. 1). Case 2: An 8-year-old boy had marked dysphonia since beginning to speech. He presented to the pediatric voice clinic with difficulty being understood. He had undergone speech therapy elsewhere with little effect and could not tolerate a per-oral telescopic laryngo-stroboscopy. Transnasal laryngo-stroboscopy revealed a large vocal fold cyst on the superior and medial aspect of the left true vocal fold with a contact point of decreased pliability on the contralateral fold (see Fig. 2). After excision of this cyst, the child underwent 2 weeks of voice rest and both he and his family are pleased with his improved voice quality and his ability to make himself understood. Post-operative flexible laryngo-stroboscopy reveals enhanced vibration with improved pliability of the pathological vocal fold and more symmetric mucosal waves.
Fig. 1 Trans-nasal digital laryngo-stroboscopic image of case 1. On the left is the supraglottic structures with the supraglottic/glottic synechiae evident. On the right is a close evaluation of the glottic structures with the remaining vocal cord apparent.
218
C.J. Hartnick, S.M. Zeitels
Fig. 2 Trans-nasal digital laryngo-stroboscopic images of an 8-year-old boy with a right true vocal fold cyst: preoperatively (left image) and post-operatively (right image) after suspension microlaryngoscopy and excision.
3. Discussion The application of stroboscopy to the evaluation of patients with voice disorders has allowed for the refinement of diagnoses as well as to more precise pre- and post-operative evaluation and planning either in terms of surgical or speech therapy strategies. Per-oral laryngo-stroboscopy is performed by means of a standard rigid Hopkins rod angled telescope. Through this technique, highly accurate images of the vocal folds can be obtained as the glottis cycles during respiration and then in phonation. The limitations of this technique arise from the need for substantial cooperation during a per-oral examination. With the tongue protruding, the head extended and the neck flexed, it is difficult to simulate the conditions associated with conversational phonation. Alternatively, the flexible stroboscope allows for a more normal head position as well as for more ease in speech during the examination. Other advantages of flexible laryngo-stroboscopy include a greater tolerance of passage of the scope through a trans-nasal rather than a per-oral route in some patients (especially children) because of a diminished need to a hyperactive gag reflex. These advantages are particularly important when analyzing the young child with a voice disorder as this examination has traditionally remained a challenging problem. Dejonckere reported that the incidence of vocal problems in children has been estimated as 6—9% of the population [14]. The main etiologies for children presenting for a vocal issue can be defined as organic (congenital/acquired), functional/ habitual (voice abuse and misuse) and psychogenic [14]. Many of the diagnoses within these categories require close evaluation of the larynx with small flexible trans-nasal endoscopes. For children under 3, small endoscopes of 2.3 mm are routinely used as the larger 4.0 mm scopes are too large to pass through a young child’s
nasal chamber. From birth to 2 months of age, the median right anterior mucosal width of the nares (the distance from the inferior aspect of the middle turbinate to the septum on CT imaging) has been reported as 2.91 0.94 mm which explains the need for the smaller diameter nasal endoscopes [15]. Although the growth of the nasal choanae has been well documented [16—18], there remains a relative paucity of information regarding the actual growth and dimensions of the anterior and middle regions of the normal healthy infant’s nose. This limits a better understanding of the optimal diameter endoscope that should be used for a given child and future research is needed. The present endoscopes of 3.8 mm and the newer 3.2 mm endoscopes being developed come closer to the size at which a more comfortable endoscopy can be performed and, the coupling of stroboscopy to these scopes, presents an impressive technological discovery that should allow for more refined clinical investigations and diagnoses. The are a number of limitations of the current trans-nasal flexible digital stroboscopes, however, there is promise of further innovation. The distal tip of the smallest current scope on the market is 3.8 mm which is still too large in diameter to readily access the younger child and the infant. The prototype scope of 3.2 mm comes closer to being functional at all ages and was readily passed in the 19 month old girl examined. With this endoscope, glottal aperture and vocal fold contour can be observed but there remains limited information to be gleaned regarding mucosal pliability as compared to the rheologic information that can be gathered from larger rigid Hopkins rod telescopes. The challenge remains to produce smaller digital chips that allow for smaller distal diameter scopes to be developed. Moreover, a working side port will be essential, which currently exists only in the larger diameter flexible scopes, if novel technology such
Pediatric video laryngo-stroboscopy
as the 585 nm pulsed dye laser is used for officebased treatment of certain disorders such as laryngeal papilloma [19]. In conclusion, new technological advancements in trans-nasal flexible laryngo-stroboscopy provide the potential for expanding the population of children who can be examined. Larger studies will be necessary to determine its limitations related to age, development, and disease. As with adults, making accurate laryngo-stoboscopic imaging is essential to employ optimal state of the art management. Further longitudinal studies are currently underway to continue to refine techniques of pediatric voice assessment and to define limitations of this new technology.
References [1] J. Bishop, Experimental researches into the physiology of the human voice, Lond. Edinb. Philos. Mag., J. Sci. (1836). [2] M. Oertel, Ueber eine neues laryngostroboskopische Untersuchungsmethode des kehlkopfes, Centralblatt Medizinischen Wiss. 16 (1878) 81—82. [3] M. Oertel, Das laryngostrobokop und die Laryngostroboskpische untersuchung, Arch. Laryngol. Rhinol. 3 (1895) 1—16. [4] Leden Hv, P. Moore, R. Timcke, Laryngeal vibrations: measurements of the glottic wave. Part III. The pathologic larynx, Arch. Otolaryngol. 71 (1960) 16—35. [5] Hv. Leden, The electronic synchron-stroboscope: its value for the practising laryngologist, Ann. Otol. Rhinol. Laryngol. 70 (1961) 881—893. [6] H.J. Rubin, M. LeCover, Technique of high speed photography in the larynx, Ann. Otol. Rhinol. Laryngol. 69 (1960) 1072—1082. [7] D. Farnsworth, High Speed Motion Pictures of Human Vocal Cords, Bell Telephone Laboratories, 1940.
219
[8] J. Van-den-Berg, Myoelastic-aerodynamic theory of voice production, J. Speech Hear. Res. 1 (1958) 227—244. [9] M. Hirano, Phonosurgery. Basic and clinical investigations, Otologia (Fukuoka) 21 (Suppl. 1) (1975) 239—260. [10] J. Hirschberg, P.H. Dejonckere, M. Hirano, K. Mori, H.J. Schultz-Coulon, K. Vrticka, Voice disorders in children, Int. J. Pediatr. Otorhinolaryngol. 32 (Suppl.) (1995) S109— S125. [11] A. Kirstein, Comparison between autoscopy and laryngoscopy: examination of children, F.A. Davis Co., Philadelphia, 1897, pp. 44—46. [12] K. Sato, H. Umeno, T. Nakashima, Stroboscopic observation of vocal fold vibration with the videoendoscope, Ann. Otol. Rhinol. Laryngol. 112 (2003) 965—969. [13] D. Colden, S.M. Zeitels, R.E. Hillman, J. Jarboe, G. Bunting, K. Spanou, Stroboscopic assessment of vocal fold keratosis and glottic cancer, Ann. Otol. Rhinol. Laryngol. 110 (2001) 293—298. [14] P.H. Dejonckere, Voice problems in children: pathogenesis and diagnosis, Int. J. Pediatr. Otorhinolaryngol. 49 (Suppl. 1) (1999) S311—S314. [15] P. Contencin, L. Gumpert, J. Sleiman, L. Possel, I. De Gaudemar, C. Adamsbaum, Nasal fossae dimensions in the neonate and young infant: a computed tomographic scan study, Arch. Otolaryngol. Head Neck Surg. 125 (1999) 777— 781. [16] D.M. Crockett, G.B. Healy, T.J. McGill, E.M. Friedman, Computed tomography in the evaluation of choanal atresia in infants and children, Laryngoscope 97 (1987) 174—183. [17] K.D. Sweeney, R.W. Deskin, J.A. Hokanson, C.P. Thompson, J.K. Yoo, Establishment of normal values of nasal choanal size in children: comparison of nasal choanal size in children with and without symptoms of nasal obstruction, Int. J. Pediatr. Otorhinolaryngol. 39 (1997) 51—57. [18] T.L. Slovis, B. Renfro, F.B. Watts, L.R. Kuhns, W. Belenky, J. Spoylar, Choanal atresia: precise CT evaluation, Radiology 155 (1985) 345—348. [19] S.M. Zeitels, R.A. Franco, S.H. Dailey, J.A. Burns, R.E. Hillman, R.R. Anderson, Office-based treatment of glottal dysplasia and papilloma with the 585 nm pulsed dye laser and local anesthesia, Ann. Otol. Rhinol. Laryngol. 113 (2004) 265—276.
www.elsevier.com/locate/ijporl
Pediatric video laryngo-stroboscopy Christopher J. Hartnicka,*, Steven M. Zeitelsb a
Department of Otology and Laryngology, Division of Pediatric Otolaryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114-3914, USA b Department of Surgery, Massachusetts General Hospital, Boston, MA, USA Received 24 July 2004; accepted 29 August 2004
KEYWORDS Laryngoscopy; Stroboscopy; Pediatric hoarseness; Dysphonia; Glottic; Glottis
Summary Objective : Laryngo-stroboscopy remains as the clinical gold standard for assessing properties of the glottal phonatory and valvular function. This includes deficits of closure as well as mucosal wave irregularities secondary to abnormal zones of pliability and symmetry. Per-oral stroboscopy has technical limitations in children due to the size of the telescope and issues of patient compliance. However, flexible laryngoscopy is readily performed in newborns and young children. This paper describes the use of a new trans-nasal, digital flexible laryngoscope, which allows for laryngo-stroboscopy in children. Methods and results : A prospective longitudinal series was done on 25 children ages 19 months—13 years (mean age, 7.0 years) with this new technology. All 25 were successfully examined. Conclusions : New technological advancements in the design of digital flexible endoscopes has allowed for laryngo-stroboscopy, and therefore, provides the potential for expanding the population of children with vocal disorders in whom stroboscopic imaging is possible. Larger studies will be necessary to determine its limitations related to age, development, and disease. As the study of pediatric voice disorders continues to evolve, accurate diagnosis is essential to apply state of the art nonoperative and phonosurgical interventions. Further longitudinal studies are currently underway to continue to refine techniques of pediatric voice assessment and to define limitations of this new technology. # 2004 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
* Corresponding author. Tel.: +1 617 573 4206; fax: +1 617 573 6845. E-mail address: [email protected] (C.J. Hartnick).
Bishop, in 1836, deduced that the mucosa of the vocal fold was the primary site of vibration and that variable tension conferred on it from the underlying muscle determined pitch frequency [1]. Unfortunately, the speed of this vibration was imperceptible
0165-5876/$ — see front matter # 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2004.08.021
216
C.J. Hartnick, S.M. Zeitels
to the human eye. In 1878, Oertel attempted to solve this problem by employing a rotating pinwheel/disk to interrupt a steady beam of light during laryngoscopy to ‘‘slow down’’ the appearance of vibration [2]. Unfortunately, the initial prototype laryngeal stroboscope was conceptually sound but impractical. Effective laryngeal stroboscopy required consistent rotational velocities and this device was dependent on hand-cranking the device. By 1895, Oertel had perfected a usable laryngeal stroboscope with the effective use of electricity to control rotational velocity [3]. Stroboscopy was coupled to laryngoscopy to enhance perceptual assessment of vocal fold vibration, which is otherwise impossible given the typical frequencies of oscillation [4—6]. With technological advances in the 20th century, the ability to find novel means of exploring vocal fold vibration allowed for the landmark studies of Farnsworth at Bell Laboratories in 1938 (reported in 1940) where the motion of the vocal folds were described by the use of high speed cinematography [7]. Farnsworth’s studies, and later Van-den-Berg’s [8], described the inferior to superior opening of the vocal folds in the glottal cycle and thus described a more, complex three dimensional motion. Hirano’s
elegant pathologic studies describing the microlayered structure of the human vocal fold with a oscillating cover on a more rigid body structure gave anatomic understanding to the mechanical properties that were being observed during laryngo-stroboscopy [9]. Because of the perceptual limitations of routine laryngoscopy, rigid, telescopic video laryngo-stroboscopy has become a standard and essential tool for a laryngologist to study phonatory disorders. For the inexperienced, it can be a technically challenging exam to accomplish skillfully and to interpret. Furthermore, it has limitations for patients with a strong gag reflex and for children. This is further complicated by the fact that transoral rigid telescopes provide enhanced optical resolution and many children cannot tolerate transoral rigid endoscopy [10]. This observation was made by Kirstein over a century ago when he explained that transoral mirror laryngoscopy was problematic in children, and therefore, he correctly predicted that transoral direct laryngoscopy would substantially enhance the evaluation of young children with laryngeal problems [11]. ‘‘In all probability autoscopy (direct laryngoscopy) will assume an important role in the examination of children, on an equal footing
Table 1 Description of pediatric population undergoing trans-nasal digital laryngo-stroboscopy Patient
Age
Gender
Presenting diagnosis
Trans-nasal stroboscopy
Diagnosis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
11.00 13.00 9.00 10.00 8.00 1.50 6.00 13.00 6.00 8.00 10.00 6.00 3.00 5.00 4.00 8.00 10.00 9.00 4.00 5.00 3.00 6.00 9.00 4.00 5.00
Female Male Male Male Male Female Male Female Female Male Female Male Male Female Female Female Male Male Female Male Female Female Male Male Male
Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Tracheotomy dependent Dysphonia Tracheotomy dependent Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia Dysphonia
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain JRRP Vocal cord nodules, vocal strain Posterior glottic stenosis Vocal cord cyst Supraglottal, glottal stenosis VCN LPR Vocal cord nodules, vocal strain VCN Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord cysts, vocal strain JRRP Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain Vocal cord nodules, vocal strain
JRRP: juvenile recurrent respiratory papillomatosis; VCN: vocal cord nodules; LPR: laryngopharyngeal reflux.
Pediatric video laryngo-stroboscopy
with laryngoscopy (transoral mirror examination); but in preference to laryngoscopy in very young children. Even infants can be examined with the autoscope (direct laryngoscope) . . ..’’ Many patients, both adults and children, better tolerate flexible laryngoscopy however, the flexible stroboscopic examination is less valuable than with a rigid telescope due to diminished optical resolution. Recently, there has been a report about improvements in flexible laryngoscopes by using digital technology for flexible laryngo-stroboscopy which has allowed for enhanced video laryngo-stroboscopy in adults [12]. Previously, narrow-diameter pediatric flexible laryngoscopes have been incapable of stroboscopy, however, adapting digital technology to narrow-diameter flexible laryngoscopes has allowed for stroboscopy in children. We believe that many diagnostic and therapeutic advancements in adult phonosurgery and phonomedicine have yet to be consistently transferred to the pediatric population and laryngeal stroboscopy is but one example. Towards this end, a prospective trial was done to assess its stroboscopic feasibility and utility of a narrow diameter, flexible digital laryngeal stroboscope in children. Between July 1, 2003 and March 1, 2004, 25 children presenting to an outpatient tertiary care pediatric laryngologic voice clinic underwent transnasal flexible laryngo-stroboscopy as part of their formal voice evaluation. Either the Pentax VNL-1130 (distal tip diameter, 3.8 mm), the Olympus ENF type V (distal tip diameter, 3.9 mm), or an Olympus prototype (distal tip diameter, 3.2 mm) were used. Their mean age was 8.4 years. Table 1 describes this population.
2. Results All 25 children tolerated trans-nasal flexible examination with minimal discomfort. In all cases, identifiable laryngeal anatomy was clearly visualized to
217
facilitate a diagnosis. Since stroboscopy is a subjective assessment tool [13], no attempt was made to treat it as an objective measure of vocal function. Two cases are delineated below to serve as illustrative examples of how stroboscopy was helpful in clinical management. Case 1: A 12-year-old girl had sustained a motor accident with prolonged intubation and the development of subglottal stenosis. She had undergone three CO2 laser procedures and two attempted laryngotracheal reconstructions previously at an outside institution and presented the pediatric voice clinic with a chief compliant of marked dysphonia as well as tracheotomy dependence. She had a hyperactive gag reflex and could not tolerate a per-oral stroboscopy. Close trans-nasal stroboscopic evaluation of her glottis was essential as she had extensive glottal and subglottal stenosis and identification of remaining pliable mucosa was essential to plan a planned endoscopic and open repair to facilitate decannulation while preserving her voice to the greatest extent possible (see Fig. 1). Case 2: An 8-year-old boy had marked dysphonia since beginning to speech. He presented to the pediatric voice clinic with difficulty being understood. He had undergone speech therapy elsewhere with little effect and could not tolerate a per-oral telescopic laryngo-stroboscopy. Transnasal laryngo-stroboscopy revealed a large vocal fold cyst on the superior and medial aspect of the left true vocal fold with a contact point of decreased pliability on the contralateral fold (see Fig. 2). After excision of this cyst, the child underwent 2 weeks of voice rest and both he and his family are pleased with his improved voice quality and his ability to make himself understood. Post-operative flexible laryngo-stroboscopy reveals enhanced vibration with improved pliability of the pathological vocal fold and more symmetric mucosal waves.
Fig. 1 Trans-nasal digital laryngo-stroboscopic image of case 1. On the left is the supraglottic structures with the supraglottic/glottic synechiae evident. On the right is a close evaluation of the glottic structures with the remaining vocal cord apparent.
218
C.J. Hartnick, S.M. Zeitels
Fig. 2 Trans-nasal digital laryngo-stroboscopic images of an 8-year-old boy with a right true vocal fold cyst: preoperatively (left image) and post-operatively (right image) after suspension microlaryngoscopy and excision.
3. Discussion The application of stroboscopy to the evaluation of patients with voice disorders has allowed for the refinement of diagnoses as well as to more precise pre- and post-operative evaluation and planning either in terms of surgical or speech therapy strategies. Per-oral laryngo-stroboscopy is performed by means of a standard rigid Hopkins rod angled telescope. Through this technique, highly accurate images of the vocal folds can be obtained as the glottis cycles during respiration and then in phonation. The limitations of this technique arise from the need for substantial cooperation during a per-oral examination. With the tongue protruding, the head extended and the neck flexed, it is difficult to simulate the conditions associated with conversational phonation. Alternatively, the flexible stroboscope allows for a more normal head position as well as for more ease in speech during the examination. Other advantages of flexible laryngo-stroboscopy include a greater tolerance of passage of the scope through a trans-nasal rather than a per-oral route in some patients (especially children) because of a diminished need to a hyperactive gag reflex. These advantages are particularly important when analyzing the young child with a voice disorder as this examination has traditionally remained a challenging problem. Dejonckere reported that the incidence of vocal problems in children has been estimated as 6—9% of the population [14]. The main etiologies for children presenting for a vocal issue can be defined as organic (congenital/acquired), functional/ habitual (voice abuse and misuse) and psychogenic [14]. Many of the diagnoses within these categories require close evaluation of the larynx with small flexible trans-nasal endoscopes. For children under 3, small endoscopes of 2.3 mm are routinely used as the larger 4.0 mm scopes are too large to pass through a young child’s
nasal chamber. From birth to 2 months of age, the median right anterior mucosal width of the nares (the distance from the inferior aspect of the middle turbinate to the septum on CT imaging) has been reported as 2.91 0.94 mm which explains the need for the smaller diameter nasal endoscopes [15]. Although the growth of the nasal choanae has been well documented [16—18], there remains a relative paucity of information regarding the actual growth and dimensions of the anterior and middle regions of the normal healthy infant’s nose. This limits a better understanding of the optimal diameter endoscope that should be used for a given child and future research is needed. The present endoscopes of 3.8 mm and the newer 3.2 mm endoscopes being developed come closer to the size at which a more comfortable endoscopy can be performed and, the coupling of stroboscopy to these scopes, presents an impressive technological discovery that should allow for more refined clinical investigations and diagnoses. The are a number of limitations of the current trans-nasal flexible digital stroboscopes, however, there is promise of further innovation. The distal tip of the smallest current scope on the market is 3.8 mm which is still too large in diameter to readily access the younger child and the infant. The prototype scope of 3.2 mm comes closer to being functional at all ages and was readily passed in the 19 month old girl examined. With this endoscope, glottal aperture and vocal fold contour can be observed but there remains limited information to be gleaned regarding mucosal pliability as compared to the rheologic information that can be gathered from larger rigid Hopkins rod telescopes. The challenge remains to produce smaller digital chips that allow for smaller distal diameter scopes to be developed. Moreover, a working side port will be essential, which currently exists only in the larger diameter flexible scopes, if novel technology such
Pediatric video laryngo-stroboscopy
as the 585 nm pulsed dye laser is used for officebased treatment of certain disorders such as laryngeal papilloma [19]. In conclusion, new technological advancements in trans-nasal flexible laryngo-stroboscopy provide the potential for expanding the population of children who can be examined. Larger studies will be necessary to determine its limitations related to age, development, and disease. As with adults, making accurate laryngo-stoboscopic imaging is essential to employ optimal state of the art management. Further longitudinal studies are currently underway to continue to refine techniques of pediatric voice assessment and to define limitations of this new technology.
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