The use of topical anesthetic in videostroboscopic examination of the larynx

Journalof Voice

Vol.5, No. 1, pp. 57--63 ©1991RavenPress, Ltd., New York

The Use of Topical Anesthetic in Videostroboscopic Examination of the Larynx Robert C. Peppard and Diane M. Bless Departments of Surgery and Communicative Disorders and Waisman Center, University of Wisconsin, Madison, Wisconsin, U.S.A.

Summary: The use of topical anesthetic spray in the oropharynx to reduce excessive gag reflex and permit endoscopic videostroboscopy of the larynx is a common clinical practice. However, clinical observations and some studies have indicated that such use may alter physiological status and result in adverse changes in laryngeal activity. This study examined possible effects of topical anesthetic on a wide range of laryngeal activity assessed with videostroboscopy. Laryngeal activity of l0 young adults with normal larynges was evaluated with and without lidocaine. Results indicated that the use of topical anesthetic ~to reduce the gag reflex did not affect vocal performance and may have examination benefits. Key Words: Larynx--Videostroboscopic measures--Topical anesthetic.

The clinical value of videostroboscopic examination of the larynx for evaluation and management of voice disorders has been well established (1). Observations of vibratory patterns made possible by stroboscopy have been found to be diagnostically useful. Parameters of interest include glottal shape, amplitude of movement, presence of mucosal wave, and timing relationships between opening and closing (2,3). Videostroboscopic examinations are usually performed with a rigid endoscope or a flexible fiberscope. The rigid endoscope is thought to have several advantages over the flexible fiberscope because it offers a clearer, sharper, and larger image of the entire vocal fold, allowing precise documentation of anatomical or structural changes of the larynx (4). However, our clinical experience has

shown that approximately 10% of people examined with the rigid endoscope experience a hypersensitive gag reflex during endoscopic examination that makes the stroboscopic procedure difficult if not impossible to complete. Moreover, some subjects who do tolerate the endoscope exert great effort in suppressing the gag reflex and may therefore increase vocal fold tension and thus modify phonation. A common clinical procedure to reduce oral sensation and excessive gagging and permit endoscopic laryngeal examination is the use of a topical anesthetic such as Xylocaine (lidocaine) 10% Oral Spray (5). Xylocaine oral spray acts on intact mucous membranes to produce local anesthesia by inhibiting the ionic fluxes required for the initiation and conduction of neural impulses. Anesthesia usually occurs within 1-2 min and persists for approximately 10-15 rain. Adverse side effects are usually dose-related, with overdoses possibly resulting in CNS symptoms such as light-headedness, confusion, or dizziness and cardiovascular system manifestations such as bradycardia or hypotension. More rarely, allergic reactions, including lesions, edema, and ana-

This paper was presented at the annual convention of The American Speech-Language-Hearing Association (ASHA), November 18-21, 1988. Address correspondence and reprint requests to Robert C. Peppard, Waisman Center on Mental Retardation and Human Development, 1500 Highland Ave, Madison, WI 53705-2280, U.S.A.

57

58

R. C. P E P P A R D A N D D. M. B L E S S

phylactoid reactions, may occur. Extreme caution is recommended in the use of topical anesthetic in the presence of extremely traumatized mucosa where rapid systemic absorption is possible. Precautions recommended to manage possible adverse reactions when lidocaine is administered to mucous membranes include the presence of resuscitative equipment, oxygen, and resuscitative drugs (6). It has usually been assumed in clinical practice that use of intraoral topical anesthetic does not affect laryngeal observations, either because too little of the spray reaches the folds to have an observable effect on vibration or because sensory changes in the oral pharynx do not subsequently alter laryngeal function. Yanagisawa (4), however, in comparing the advantages of rigid versus flexible stroboscopic examination, stated that normal laryngeal function, especially phonation, is altered when local anesthesia is used for videostroboscopic examination and that anesthetic-induced phonatory change is one of the disadvantages of telescopic examination. It has also been suggested that laryngeal secretions may be modified by the presence of topical anesthesia, either as the result of a neurologic response or by stimulation of the goblet cells located in the larynx (7). No experimental data exist to support these clinical reports, though numerous studies have examined the effects on various phonatory functions of topical anesthesia when it is. applied directly to the vocal folds. Results have been equivocal, with some researchers finding changes in phonatory function while others found no such change. Sorenson et at. (8) suggested that topical anesthesia, when applied directly to the folds, results in deprivation of reflexogenic ties with the mucous membranes, disruption of steady phonation, and deviations in fine laryngeal behaviours such as jitter. Other changes reported in the presence of topical anesthetic include larger phonatory adjustment times (9,10) and increased glottal resistances of laryngeal mucosa (1 I). On the other hand, some investigators have found that topical anesthesia applied directly to the folds had no effect on glottal area function, vibratory pattern of the folds, or intensity (12-14). None of the studies to date have examined the impact of topical anesthesia on the vibratory characteristics of the folds as visualized with videostroboscopy, nor have they determined what affect anesthesia applied to the supraglottis might have on phonation.

Journal of Voice, Vol. 5, No. 1, 1991

RATIONALE Possible alterations in secretions, supraglottic activity, mucosal wave, symmetry, periodicity, and amplitude of the vibrating folds due to the use of topical anesthetic could bias the evaluation and management of persons with vocal pathologies. The changes in vocal fold condition caused by the anesthetic might seem to be the result of the vocal pathology, thus leading to inappropriate recommendations and intervention. However, if it can be shown that such use does not change stroboscopic observations, it might be possible that more frequent use of topical anesthetic could benefit patients with voice disorders by making the examination more comfortable, and providing better images. PURPOSE It was the purpose of our study to determine what effect the routine clinical use of topical anesthetic applied during v i d e o s t r o b o s c o p i c examination might have on a wide range of vocal fold activities that are typically assessed videostroboscopically. MATERIALS AND METHODS Subjects Videostroboscopic recordings of vocal fold vibrations were obtained in l0 young adult subjects, five men and five women, 20-39 years old. All had normal voice production and were selected based on their ability to tolerate the rigid endoscope without use of a topical anesthetic. Videotapes of each subject's larynx were reviewed and identified as normal by a certified otolaryngologist. Examination procedure All examinations were conducted in an otolaryngology clinic where resuscitative measures were available to handle any adverse reactions to the topical anesthetic. Subjects were seated in a dental chair with their mouths open and tongues extended. A 90 ° angle Wolfe rigid endoscope with an outer diameter of 11 mm was positioned in the oral cavity so that, to the extent possible, the position of the lens was parallel to the floor to avoid laryngeal image distortion. The image was in the center of the viewing field, and the entire length of the glottis could be visualized. The opposite end of the endoscope was attached to a Wolf Endocam Camera, a Bruel and Kjaer strobo-

ANESTHETICS I N L A R Y N G E A L EXAMINATIONS

scopic light generator with a digital frequency indicator (model #4914 with a combined Xenon and Halogen light source), and a Hitachi (VT-8A) VHS ½-inch video recording system. A laryngeal microphone placed on the thyroid lamina was used to detect the vibrations produced in the larynx, and a Sony electret microphone was used to record audio signals. The video signal received from the stroboscopic generator and endoscopic-camera system was fed to a Sony Trinitron monitor with a 12-in screen (model KV-1331). Continuous frame numbers were displayed on the bottom of the monitor screen. Once the examiner had introduced the endoscope into the subject's mouth, the examination light was activated by a foot pedal. The subject was instructed to phonate an/i/-like sound at a comfortable pitch and loudness without raising his or her tongue so that the tongue would not interfere with appropriate placement of the scope. Phonation activated the strobe light. The subject was asked to sustain each production for at least 5 s. The examiner noted and recorded the fundamental frequency displayed on the strobe generator. Each subject was recorded while producing a standard protocol consisting of the vowel/i/at normal pitch and loudness, highest and lowest pitch at normal loudness, normal pitch at increased and decreased loudness, and laryngeal diadochokinesis at normal pitch and loudness.

Treatment Two separate videostroboscopic recordings were made for each subject, one with and one without 30 nag of Xylocaine spray. The preparation was sprayed on the structures of the oropharynx including the posterior dorsum of the tongue, velum, faucial pillars, and posterior pharyngeal wall in three metered doses. Maximum effect was achieved in 2 min. Order of the treatment was randomized to avoid an ordering effect in subject performance. For those subjects who were anesthetized during the first recording, at least 60 min was allowed for the effects of the anesthetic to subside before the second recording was made. Rating procedure The 20 video samples obtained, plus five repeated samples to test reliability, were randomly duplicated onto a 60-min viewing tape for evaluation. The experimental tape was replayed on a highquality video system for two judges with extensive

59

knowledge of vocal fold function and previous experience in rating laryngeal videostroboscopic images. They evaluated the samples using the Stroboscopic Assessment of Voice form (2), which uses a six-point interval scale from normal to severely impaired, to rate laryngeal variables including type of closure, supraglottic activity, vertical level, amplitude, glottal wave, nonvibrating portion, phase symmetry, phase closure, and periodicity. An additional rating was made to account for possible changes in the amount and type of secretions in the laryngeal area. Secretions were rated as either unremarkable or remarkable. Unremarkable indicated that there was a normal amount and type of secretions and that the folds glistened with a slight sheet of mucous. Secretions were rated as remarkable if there were reduced or excessive amounts of mucous or unusual mucous conditions such as pooling, ball formation, or stranding; these conditions are thought to indicate glottal irritation (15). RESULTS Analysis of the data showed test-retest reliability for the judges to be 0.96, while interjudge reliability was found to be 0.87. Both results were significant (p < 0.05). Results for five of the parameters evaluated--closure, vertical level, glottal wave, nonvibrating portion, and periodicity--were rated normal for all 10 subjects with no changes noted in the presence of anesthetic. Table 1 summarizes the four parameters of strobe ratings for which some abnormalities were noted T A B L E 1. Pretreatment and posttreatment ratings for

each subject for the four categories in which changes occurred Pretreatment

Posttreatment

Subject number

SA

AM

PC

S

SA

AM

PC

S

1 2 3 4 5 6 7 8 9 10 Total

1 1 2 2 1 1 2 2 1 2 15

1 1 1 1 2 1 1 1 1 1 11

1 1 1 1 1 2 1 1 1 1 11

1 1 2 2 1 2 2 2 1 2 16

1 2 2 2 1 1 2 2 1 1 15

1 1 1 1 1 1 1 1 1 1 10

1 1 1 1 1 1 1 1 1 1 10

1 1 2 2 1 2 2 2 1 1 15

SA, supraglottic activity; AM, amplitude of movement; PC, phase closure; S, secretions.

Journal of Voice, Vol. 5, No. 1, 1991

60

R. C. P E P P A R D A N D D. M. B L E S S

and for which both positive and negative changes took place when topical anesthetic was applied. These were supraglottic activity, amplitude, phase closure, and secretions. In all cases where samples were rated as abnormal, they were noted to be only mildly impaired, with no rating in any category greater than two on the six-point scale. In the category of supraglottic activity, 5 of the 10 subjects had slight medial Compression of the ventricular folds pretreatment. Four of these subjects continued to have supraglottic activity following treatment while one subject did not have such activity posttreatment. Conversely, a subject who had normal supraglottic activity pretreatment was noted to exhibit increased activity with anesthetic. One subject had slightly decreased amplitude without anesthetic, but a normal amplitude rating with treatment. One subject had a slightly increased closed phase pretreatment but normal phase closure with anesthetic. Six of the 10 subjects were rated as having remarkable levels of secretions pretreatment. Ratings for five subjects remained the same with treatment while one subject's rating changed to unremarkable with anesthetic. A computer statistical software package (Minitab) was used to calculate Sign tests for each measure to identify any significant difference in treatment and nontreatment conditions. No significant

FIG. 1. Videoprint of an unremarkable larynx with little m u c o u s accumulation.

Journal of Voice, Vol. 5, No. 1, 1991

differences (p < 0.05) were found in any of the categories rated between the two conditions. DISCUSSION It is apparent that a percentage of the healthy subjects was rated abnormal on several parameters, even in the absence of topical anesthetic. This was especially true for mucous ratings, where many of the subjects showed notable levels of secretions before the application of anesthetic. Figures 1--4 illustrate a range of laryngeal secretion conditions observed in the normal speakers from this study. Figure 1 shows a videoprint of an unremarkable larynx with little mucous accumulation-typical for only four of the ten subjects. The remaining six subjects exhibited varied patterns. Figure 2 shows two samples rated as notable. Figure 2A shows mucous pooling at the anterior commissure, while Figure 2B shows pooling at the posterior commissure. Figure 3 demonstrates a pattern described as mucous ball formation. Figure 4 shows mucous stranding between the vocal folds. A number of conclusions regarding the effects of topical anesthetic on laryngeal strobe ratings for healthy subjects can be drawn from these data. Contrary to several reports in the literature concerning anesthetic applied directly to the vocal folds, the data reported here indicate that use of

ANESTHETICS IN LARYNGEAL EXAMINATIONS

61

FIG. 2. Videoprints of remarkable secretion levels. A: Mucous pooling at the anterior commissure. B: Mucous pooling at the posterior commissure.

topical anesthetic in videostroboscopic examination does not result in observable changes in vocal performance. All but one of the differences noted in vocal ratings with anesthetic reflected improved phonatory function, though results were not statistically significant. There are seVeral possible explanations for these

findings, relating to the magnitude of the anesthesia used, the placement of the anesthesia, and the observation technique used. For example, while the amount of topical anesthesia used in this study was sufficient to anesthetize the oropharynx and suppress the gag reflex, it may not have been sufficient to affect the vocal folds. This makes it difficult to

Journal of Voice, Vol. 5, No. 1, 1991

62

R . C. P E P P A R D A N D D . M . B L E S S

FIG. 3. Videoprintshowingmucousballformation.

compare our results directly with those reported in the literature where topical anesthetic was applied directly to the vocal folds. If the anesthetic used in the current study changed the sensory aspects of the folds, it is clear that it was inadequate to alter the phonatory features observable with the videostroboscopic system. Hirano (16) has suggested that the videostro-

boscopic procedure itself may limit our ability to note changes in vocal function in the presence of anesthetic. Standard videotape recording is limited to 30 frames per second. With stroboscopy, the video image of one cycle is obtained from different portions of several cycles such that one does not actually see the entire vibratory event, but rather sees an apparent cycle, consisting of a composite

FIG. 4. Videoprint demonstrating mucous stranding between the vocal folds.

Journal of Voice, Vol. 5, No. 1, 1991

ANESTHETICS IN LARYNGEAL EXAMINATIONS

image from several cycles. Therefore, it is possible that subtle alterations in vocal fold activity resulting from the presence of a topical anesthetic can be missed. It may be that other measurement techniques such as high-speed cinematography or acoustical analysis would reveal changes that videostroboscopy did not. 0f particular interest was the observation that abnormal perceptual ratings occurred for subjects without any history or complaint of voice disorder. It may be, as numerous reports (2,16,17) have suggested, that our ideal picture book image of the larynx as a symmetrical apparatus is incorrect and that normal voice production is possible even in the presence of asymmetries and irregularities. Finally, current strobe rating protocols developed for use with pathological subjects may not adequately account for variability within healthy subject populations. Implications of the findings from this investigation include the need to modify rating protocols to adequately reflect the range of performance in speakers with no reported voice pathology. Obtaining a normal data base is an essential first step to better understanding characteristics of laryngeal function in healthy and disordered structures. Despite possible examination variables, it seems reasonable to conclude that topical anesthetic does not measurably alter videostroboscopic observations and that use of anesthetics such as lidocaine can benefit patients by resulting in better images and making the examination more comfortable. A note of caution must be made that, since lidocaine is more rapidly absorbed in the presence of sepsis or traumatized mucosa, as is present in some voice-disordered patients, topical anesthetic must only be administered in a medical setting where patient response can be monitored and possible adverse side effects such as vagal reactions can be quickly managed by appropriate medical personnel. With this caution in mind, it is recommended that topical anesthetic be used with patients who report they gag easily, patients who are judged by the examiner to be particularly tense prior to the examination, patients who gag when the endoscope is in-

63

serted into the oropharynx, and patients who exert great effort to suppress their gag reflex. Use of topical anesthetic in these patients should result in improved laryngeal images and enable more appropriate management decisions concerning voice disorders. Acknowledgment: Supported by NINCDS Grant NS 24859. REFERENCES I. Hirano M. Clinical examination of voice. New York: Springer-Verlag, 198l. 2. Bartell T, Bless D, Ford C. Stroboscopic examination of voice: a comparison of two procedures. In: Hirano M, Hibi S, Bless D, eds. Proceedings of the International Conference on Voice. Kurume, Japan: Kurume University Press, 1981 :ii15-21. 3. Shaikh A, Bless D. Preliminary comparison of vocal fold vibration with strobotelescopic and strobofibroscopic examinations. In: Hirano M, Hibi S, Bless D, eds. Proceedings of the International Conference on Voice. Kurume, Japan: Kurume University Press, 1986:ii9-14. 4. Yanagisawa E. Fiberscopic and telescopic videolaryngoscopy--a comparative study. In: Baer T, Sasaki C, Harris K, eds. Laryngeal function in phonation and respiration. Boston: College Hilt Press, 1987:475-84. 5. Tucker HM. The larynx. New York: Thieme Medical, 1987. 6. Physicians desk reference. 41st ed. Oradell, NJ: Medical Economics, 1987. 7. Gracco C. Personal communication, 1988. 8. Sorenson D, Horii Y, Leonard S. Effects of laryngeal topical anesthetic on voice fundamental frequency perturbation. J Speech Hear Res 1980;23:274. 9. Mallard AR, Ringel RL, Horii Y. Sensory contributions to control of fundamental frequency of phonation. Folia Phoniatr 1978;30:199-213. 10. Leonard RJW. Vocal shadowing under conditions of normal and altered laryngeal sensation. Unpublished doctoral dissertation. West Lafayette, IN: Purdue University, 1976. 11. Gould W, Okamura H. Interrelationships between voice and laryngeal mucosal reflexes. In: Wyke B, ed. Ventilatory and phonatory control systems. London: Oxford University Press, 1974:347-59. 12. Faaborg-Anderson K. Electromyographic investigation of intrinsic laryngeal muscles in humans. Acta Physiol Scand 1957;41(suppl 140):1-149. 13. Hollien H. Vocal pitch variation related to changes in vocal fold length. J Speech Hear Res 1960;3:150-6. 14. Iwamura S. An experimental study of control of vocal intensity. J Otolaryngol Jpn 1967;70:728-44. 15. Brodnitz F. Vocal rehabilitation. Rochester, MN: American Academy of Ophthalmology and Otolaryngology, 1971. 16. Hirano M. Personal communication, 1988. 17. Hicks D. Normal structural variations in the cartilages of the human larynx. Presented at the Seventeenth Annual Symposium: Care of the Professional Voice, New York, NY, June 6-10, 1988.

Journal of Voice, Vol. 5, No. 1, 1991