428
PREDICTING POSTOPERATIVE VOICE CHARACTERISTICS OF SPASTIC DYSPHONIA PATIENTS KRZYSZTOF IZDEBSKI, PhD THOMAS SHIPP, PhD BOTH BY INVITATION
HERBERT H. DEDO, MD SAN FRANCISCO, CALIFORNIA
Current treatment of spastic dysphonia may involve unilateral RLN section rreceded by a temporary chemical paralysis 0 one RLN as a diagnostic test. This study compared the Immediate postchemical paralysis and postsurgical paralysis voice and speech qualities of 33 spastic dysphonic patients using perceptual, acoustic, and temporal measurements and found that following section of the RLN, there was a decrease in overpressure and aperiodlcity, an Increase in vocal range, and a reduction of breathlness. Vocal tremor and speech rate were variably affected. It appears that chemical paralysis of the RLN Is a fairly accurate means of previewing the postsurgical voice.
hypothesis and forecast the possible results of surgical intervention, patients had one RlN chemically blocked with lidocaine, creating a temporary unilateral vocal-fold paralysis. The effects of RlN anesthesia upon spastic dysphonic phonation were dramatic but short lasting and often variable, which hampered the voice evaluation by the surgeon, the voice pathologist, and most importantly, the patient. A systematic study of the critical voice parameters in the two conditions was needed so that more accurate predictions could be made of the patient's postoperative voice.
RECENTLY, unilateral sectioning of the recurrent laryngeal nerve (RlN) was introduced as a method of treatment for spastic dysphonia, a communicative disorder affecting voice and speech.t-s It was hypothesized that deliberate paralysis of one vocal fold in a patient with spastic dysphonia would eliminate the severe spastic symptoms-apparently caused by hyperadduction-yet still allow relatively normal phonation and speech. To test the
The major goal of the study was to specify the similarities and differences in voice and speech between postanesthetic and postsurgical intervention, and to describe which features of postanesthetic phonation are good predictors of the immediate postsurgical voice and speech.
Submitted for publication June 22, 1979. From the Department of Otolaryngology, University of California, San Francisco. and the Speech Research Laboratory, VA Hospital, San Francisco. Presented at the 1978 Annual Meeting of the American Academy of Otolaryngology, Las Vegas, Sept 10U.
Reprint requests to 494U, 533 Parnassus Ave, University of California, San Francisco, CA 94143 (Dr
tzdebski).
METHOD
To study the voice and speech characteristics in the presence of an anesthetic block of RlN and after RlN section, 132 tape-recorded samples were made of 33 patients (9 men, 24 women) with a mean age of 48 years and an average ten years of spastic dysphonia. In the anesthetic block condition, either the right or left RlN of each patient was injected with 3 to 12 cc of 1% lidocaine solution adjacent to the crlco-
Otolaryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
TREATMENT OF SPASTIC DYSPHONIA thyroid joint, contiguous with the RlN entrance to the larynx. No topical anesthesia was used. In the postsurgical condition, each patient's right or left RLN was sectioned according to the method previously described.' Immediately following the injection and the indirect laryngoscopic verification of unilateral vocal fold paralysis, the patient's voice and speech production were recorded. The postsurgical voice and speech recordings were done as soon as possible, usually within 24 hours after surgical treatment, but always before initiation of speech therapy. Both sustained phonation and speech samples were used because it appeared that certain aspects of voice were more pronounced in one or the other mode. All audio recordings were made in an lAC booth, using an AKG D202E microphone coupled to a UHER 42oo-R tape recorder running at 7.5 in/sec. A constant mouth-to-microphone distance was maintained. The audio recordings comprised sustained phonation at each patient's lowest, highest, and most comfortable fundamental frequency levels, as well as a glissando-like sweep throughout the entire frequency range. The speech sample included reading a standard phonetically balanced paragraph, "The Rainbow Passage",5 conversational speech, and counting. From these tape recordings, a listening tape comprising all sustained phonatory tasks and the second and third sentences of the reading was compiled by splicing the 132 audio segments in a random order. A two-second pause was provided between each segment. Four specific perceptual qualities in voice and speech were judged by five listeners (all speech pathologists, all present authors excluded) using the absolute preference judgment method." All judgments of the four perceptual qualities were made on a 0 to 7 rating scale of the presence and magnitude of the trait. Zero
429
represented absence of the quality, while 7 denoted the maximum perceived magnitude. Before listening, each judge was familiarized with the qualities and category rating scale by listening to recorded samples representing the upper category extremes of particular qualities assigned by the experimenter. The randomized listening tape was played back via an OTARI Mark II 50-50 recorder-reproducer through an amplifier system (BGW 100), and a pair of JBL Control-Monitor Speakers (Model 4311) situated approximately 6 ft in front of the listener. Each listener was seated in an lAC booth and operated the system via remote control, choosing a most comfortable listening level. Judges had the option to listen to a segment repeatedly until a rating could be made. The four judged qualities in both speech and voice were described as (1) breathiness, (2) overpressure, (3) aperiodicity, and (4) tremor. These four qualities were chosen because they represent a minimum number of descriptors necessary to classify the principal perceptual and acoustic features of pathologic phonation studied here. "Breathiness" is probably the most common and the most agreed-upon term to indicate constant air loss irrespective of presence or absence of a fundamental tone. "Overpressure" was defined as inappropriately high subglottal air pressure for the resultant vocal output level, caused by hyperadduction of the vocal folds; it is sometimes referred to as "vocal strain." "Aperiodicity" served as a cover term for a quality characterized by noise, inharmonics in spectrum, pitch breaks, and diplophonia. "Tremor" is also self-explanatory and is manifested as slow, semicyclic changes in voice intensity or frequency, or both, irrespective of the task being performed. It is sometimes referred to as a "quaver." In addition to the perceptual ratings, each patient's voice segments in both postanesthetic and postsurgical condi-
Ofolaryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
IZDEBSKI ET AL
430
tions were measured and expressed in semitones on the musical scale. All speech samples were also assessed for rate, measured in number of syllables per second. The raw data were collated by subject, sex, and experimental conditions, and were analyzed using computer statistics?
RESULTS AND DISCUSSION Perceptual Measurements RELIABILITY Of ,UDGMENTS.- The reliability of perceptual judgments among the five judges for each condition and quality was estimated, using analysis of variance statistics. The summary of the results of these analyses is shown in Table 1. High reliability was obtained for all judges. The lowest reliability was 74% and the highest was 95%. Higher reliability was obtained overall for sustained voice segments than for speech in both conditions.
treatment. For speech, just as for voice, a statistically significant decrease in magnitude of overpressure (p-.OO1) and aperiodicity (P=- .Oll was observed postsurgically for the group. Figure 1 also indicates small but statistically nonsignificant increases in breathiness and tremor postsurgically for the whole group. The presence of overpressure in the postanesthetic condition results from a few subjects included in this study whose RLN was apparently incompletely paralyzed by the injection. In fact, repeated injections of anesthetic are sometimes necessary to paralyze the RlN and achieve any perceived change in voice qualities. As expected, both perceived overpressure and perceived aperiodicity decreased significantly postsurgically. The decrease in overpressure can be explained by a more complete vocal fold paralysis postsurgicalIy, as opposed to the sometimes incomplete chemical paralysis. Postsurgical de-
TABLE 1 MEAN RElIABILITY IN PERCENTAGES DERIVED FROM ANALYSIS OF VARIANCE FOR THE FOUR PERCEPTUAL QUALITIES
CONDITION
PAn" PAn PSut PSu
Voice Speech Voice Speech
BRE"THINESS
OVERPRESSURE
"PERIODICITY
TREMOR
('10)
('10)
('/.)
('!o)
88 85 93 91
91
95
90
90
80 74
84
91 87 93 80
89
°Poslaneslhesia. tPosl5urgery,
VOICE ANDSPEECH CHARACTERISTIC5.-
All Subjects.-Figure 1 shows the presence and the mean ratings of magnitude for the four perceived qualities of voice and speech for all subjects in both postanesthetic and postsurgical conditions. For sustained voice, there was a statistically significant (p • .005l decrease in both the perceived qualities of overpressure and aperiodicity as a result of surgical
crease in aperiodicity 'is most likely explained by the fact that during RLN block, an undesirable spread of anesthesia often occurs, affecting adjacent neural (exterior branch of the superior laryngeal nerve) and muscular tissues, whereas surgical treatment selectively paralyzes one vocal fold, leaving the cricothyroid muscle unaffected. The postanesthetic condition may create short, unstable asymmetry of
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
431
TREATMENT OF SPASTIC DYSPHONIA SPEECH
4
•
BA
....
OP
AP
tween male and female voice quality in the two conditions is difficult to explain and awaits further investigation. INTERSEX MEASURE§,-
TA
Fig l.-Mean magnitude ratings of four qualities: breathiness (BR), overpressure (OP), aperiodidty (AP), and tremor (TR) in voice and speech, comparing postanesthetic (PAn) and postsurgical (PSul conditions for the sampled population. For voice, note statistically significant (55) decrease in OP (p •• OOS) and AP (p • .OOS) in PSu condition. For speech, note the SS decrease in OP (p • .OO1) and in AP (p• .o1) in PSu condition.
vocal fold tension, contributing to aperiodic, chaotic vocal fold vlbratlons.s Furthermore, during this short anesthetic condition, a patient has little time (usually S to 20 minutes) to adjust to the sudden change in vocal fold motility and to learn to exercise full control over vocal tract function. The opposite is evident in the postsurgical condition. Intrasex Differences.-The mean judged magnitude ratings of the four perceptual qualities in postanesthetic and postsurgical conditions for voice and speech were also treated separately by sex. For voice, a statistically significant (P=.05) decrease in overpressure was observed postsurgically in men, while all other changes were not statistically significant. Women showed a statistically significant (P:o:: .01) decrease in overpressure as well as in aperiodicity (pa .D08) postsurgically. Amount of perceived breathiness remained essentially unchanged. For speech, the men showed a statistically significant difference (P- .042) only for increased breathiness in the postsurgical condition. For women, in speech, there was a decrease in the magnitude of all four qualities postsurgically, with three being statistically significant: breathiness (P-.02), overpressure (ps.D01), and aperiodicity (pa .04). The discrepancy be-
Voice.-Figure 2 shows the results of mean ratings of magnitude between men and women for each of the four qualities under postanesthetic and postsurgical conditions for voice. In the postanesthetic condition, a higher magnitude of overpressure (ps.OS) and tremor (pos.001) is observed in female voice than in male voice. In the postsurgical voice condition, there was a statistically significant difference for all four qualities between the two sex groups. The magnitude of overpressure (P=.04) and tremor (pa.D02) was judged to be greater in women than in men. The magnitude of breathiness (P=.003) and aperiodicity (P=.012), on the other hand, was judged to be less in women than in men.
•
_T ANESTHlSlA VOICE
4
i
•
II:
•
~2
l-
OJ
tuIlCIErrt
VOICE
OWl! aPEIUlJ:
4
5'
•,
~
I~ ...... n
1110'
A
T
Fig 2.-Mean magnitude ratings of four voice qualities comparing men and women in PAn and PSu conditions separately. In PAn voice condition, note 55 difference between men and women in OP (p • .OS) and TR (P•.OO1). In PSu voice condition, note SS difference between men and women in all four qualities: BR (P·.OO3), OP (P·.04), AP (P-.012), and TR (P ••OO2).
.' Speech.-Figure 3 shows the results of the mean ratings of magnitude of perceived qualities in speech of men and women in the two conditions. In the postanesthetic condition, a statistically significant (pa .001) intersex difference was observed for tremor, which was more pronounced in women. No other intersex differences were statistically significant. In
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
432
IZDEBSKI ET AL POST ANESTHESIA
SPaCH 4
s
•
~ST
SURGEill'
IPEECH
DMAlE
4
• FEMAlE
.
~3
~2
W
Fig 3.-Mean magnitude ratings of four speech qualities comparing men and women in the PAn and PSu conditions separately. In the PAn speech condition, note the SS difference between men and women in TR (P,. .(01). In PSu speech condition, note SS difference between men and women In BR (P-.001) and in TR (P-.019l.
the postsurgical condition, speech was judged to possess a greater magnitude (P=.01) of tremor in women but a lower magnitude (P=o.OO1) of breathiness than in men. Although no explanation is readily apparent for the male-female differences found, it is likely that they reflect the known anatomic and physiologic laryngeal differences between the adult sex groups.!
Physical Measurements VOCAL FREQUENCY RANGE.-The increased vocal range postoperatively of approximately five semitones for all subjects was significant. The range of voice in men in the postanesthetic condition was 11.9 semitones, and in women, 10.8 semitones. Postsurgically, the voice range was respectively 18.2 and 15.2 semitones for men and women. This postsurgical frequency range expansion of 6.3 semitones for men and 4.4 semitones for women closely approximates normal vocal function in both sex groups. Physiologically, this increase can be explained by the effect of discrete sectioning of the RLN, leaving the function of the cricothyroid muscle intact. Function of this muscle is known to be crucial for control and regulation of vocal range.'o", By contrast, in the postanesthetic condition, the function of the cricothyroid is often impaired
because of the spread of anesthesia to the muscle itself or to the superior laryngeal nerve, with a consequent vocal range reduction, as has been described repeatedly in the literature. 12. ' 5 SPEECH RATE,-In the postanesthetic condition, rate of speech was 4.0 and 3.1 syllables per second for men and women, respectively. In the postsurgical condition, the speech rate for men was 3.6 syllables per second, for women, 3.2 syllables per second. The intrasex group differences between these two conditions were not statistically significant despite some subjects demonstrating speech rate increases postsurgically. Furthermore, the female speech rate was consistently slower than the male speech rate. This intersex difference in speech rate was statistically significant (P= .001) in the postanesthetic and postsurgical conditions (P-.031).
In summary, a statistically significant decrease in overpressure and aperiodicity are observed immediately postsurgically in voice and speech when compared with the postanesthetic condition. The amount of overpressure approaches a zero rating, indicating a near absence of that perceived quality. In general, there are no postsurgical changes in the magnitude of breathiness and tremor if present in the postanesthetic condition. There are no statistically significant changes in the rate of speech for the group between the two conditions; however, a statistically significant increase in vocal range postsurgicalIy was shown by sex and for the entire . group. CONCLUSIONS
The purpose of this study was to compare the voice and speech qualities of male and female patients with spastic dysphonia after lidocaine block and section of the RLN. The goal was to evaluate the usefulness of predicting the quality of immediate post-RLN section phonation
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
TREATMENT OF SPASTIC DYSPHONIA based on the phonatory qualities observed during the chemical RLN block condition. Table 2 summarizes these predictions. The data show that changes occur in all phonatory qualities tested postsurgically when compared with postanesthetic phonation. The magnitude of aperiodicity-which is at times great, and of concern to the patient postanesthetically-decreases significantly postsurgicalIy. Follow-up findings show that residual postsurgical aperiodicity is further reduced by subsequent voice therapy. Although individual male patients may show small increases in the amount of breathiness postsurgically, in general, postanesthetic breathiness is a good predictor of immediate postsurgical breathiness. The amount of breathiness then greatly decreases throughout the first postsurgical year. Overpressure (strain) decreases significantly postsurgically from the postanesthesia condition; therefore, the presence of any overpressure during the anesthesia block condition signals incomplete chemical paralysis. In spite of some individual variations, postanesthetic speech rate and tremor are good predictors of postsurgical performance. Postanesthetic vocal range increases significantly postsurgically; therefore, vocal range is not a good predictor of postsurgical range. It must be understood, however, that the postsurgical increase in vocal range is a most important outcome, as it brings the voice closer to the expected normal function. In general, it appears that voice alone may be used as a test for all the significant changes expected to occur postsurgically. Since intersex differences in voice and speech were shown, however, a less experienced clinician should test both voice and speech. Thus, RLN block for spastic dysphonia is a conservative but an excellent and reliable predictor of the voice and speech qualities expected postsurgically. The improvement in voice and speech in spastic dysphonia patients was
433
'"o~ :x
I-
.~ >
C
QI
C
QI
E 0
~~
PREDICTING POSTOPERATIVE VOICE CHARACTERISTICS OF SPASTIC DYSPHONIA PATIENTS KRZYSZTOF IZDEBSKI, PhD THOMAS SHIPP, PhD BOTH BY INVITATION
HERBERT H. DEDO, MD SAN FRANCISCO, CALIFORNIA
Current treatment of spastic dysphonia may involve unilateral RLN section rreceded by a temporary chemical paralysis 0 one RLN as a diagnostic test. This study compared the Immediate postchemical paralysis and postsurgical paralysis voice and speech qualities of 33 spastic dysphonic patients using perceptual, acoustic, and temporal measurements and found that following section of the RLN, there was a decrease in overpressure and aperiodlcity, an Increase in vocal range, and a reduction of breathlness. Vocal tremor and speech rate were variably affected. It appears that chemical paralysis of the RLN Is a fairly accurate means of previewing the postsurgical voice.
hypothesis and forecast the possible results of surgical intervention, patients had one RlN chemically blocked with lidocaine, creating a temporary unilateral vocal-fold paralysis. The effects of RlN anesthesia upon spastic dysphonic phonation were dramatic but short lasting and often variable, which hampered the voice evaluation by the surgeon, the voice pathologist, and most importantly, the patient. A systematic study of the critical voice parameters in the two conditions was needed so that more accurate predictions could be made of the patient's postoperative voice.
RECENTLY, unilateral sectioning of the recurrent laryngeal nerve (RlN) was introduced as a method of treatment for spastic dysphonia, a communicative disorder affecting voice and speech.t-s It was hypothesized that deliberate paralysis of one vocal fold in a patient with spastic dysphonia would eliminate the severe spastic symptoms-apparently caused by hyperadduction-yet still allow relatively normal phonation and speech. To test the
The major goal of the study was to specify the similarities and differences in voice and speech between postanesthetic and postsurgical intervention, and to describe which features of postanesthetic phonation are good predictors of the immediate postsurgical voice and speech.
Submitted for publication June 22, 1979. From the Department of Otolaryngology, University of California, San Francisco. and the Speech Research Laboratory, VA Hospital, San Francisco. Presented at the 1978 Annual Meeting of the American Academy of Otolaryngology, Las Vegas, Sept 10U.
Reprint requests to 494U, 533 Parnassus Ave, University of California, San Francisco, CA 94143 (Dr
tzdebski).
METHOD
To study the voice and speech characteristics in the presence of an anesthetic block of RlN and after RlN section, 132 tape-recorded samples were made of 33 patients (9 men, 24 women) with a mean age of 48 years and an average ten years of spastic dysphonia. In the anesthetic block condition, either the right or left RlN of each patient was injected with 3 to 12 cc of 1% lidocaine solution adjacent to the crlco-
Otolaryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
TREATMENT OF SPASTIC DYSPHONIA thyroid joint, contiguous with the RlN entrance to the larynx. No topical anesthesia was used. In the postsurgical condition, each patient's right or left RLN was sectioned according to the method previously described.' Immediately following the injection and the indirect laryngoscopic verification of unilateral vocal fold paralysis, the patient's voice and speech production were recorded. The postsurgical voice and speech recordings were done as soon as possible, usually within 24 hours after surgical treatment, but always before initiation of speech therapy. Both sustained phonation and speech samples were used because it appeared that certain aspects of voice were more pronounced in one or the other mode. All audio recordings were made in an lAC booth, using an AKG D202E microphone coupled to a UHER 42oo-R tape recorder running at 7.5 in/sec. A constant mouth-to-microphone distance was maintained. The audio recordings comprised sustained phonation at each patient's lowest, highest, and most comfortable fundamental frequency levels, as well as a glissando-like sweep throughout the entire frequency range. The speech sample included reading a standard phonetically balanced paragraph, "The Rainbow Passage",5 conversational speech, and counting. From these tape recordings, a listening tape comprising all sustained phonatory tasks and the second and third sentences of the reading was compiled by splicing the 132 audio segments in a random order. A two-second pause was provided between each segment. Four specific perceptual qualities in voice and speech were judged by five listeners (all speech pathologists, all present authors excluded) using the absolute preference judgment method." All judgments of the four perceptual qualities were made on a 0 to 7 rating scale of the presence and magnitude of the trait. Zero
429
represented absence of the quality, while 7 denoted the maximum perceived magnitude. Before listening, each judge was familiarized with the qualities and category rating scale by listening to recorded samples representing the upper category extremes of particular qualities assigned by the experimenter. The randomized listening tape was played back via an OTARI Mark II 50-50 recorder-reproducer through an amplifier system (BGW 100), and a pair of JBL Control-Monitor Speakers (Model 4311) situated approximately 6 ft in front of the listener. Each listener was seated in an lAC booth and operated the system via remote control, choosing a most comfortable listening level. Judges had the option to listen to a segment repeatedly until a rating could be made. The four judged qualities in both speech and voice were described as (1) breathiness, (2) overpressure, (3) aperiodicity, and (4) tremor. These four qualities were chosen because they represent a minimum number of descriptors necessary to classify the principal perceptual and acoustic features of pathologic phonation studied here. "Breathiness" is probably the most common and the most agreed-upon term to indicate constant air loss irrespective of presence or absence of a fundamental tone. "Overpressure" was defined as inappropriately high subglottal air pressure for the resultant vocal output level, caused by hyperadduction of the vocal folds; it is sometimes referred to as "vocal strain." "Aperiodicity" served as a cover term for a quality characterized by noise, inharmonics in spectrum, pitch breaks, and diplophonia. "Tremor" is also self-explanatory and is manifested as slow, semicyclic changes in voice intensity or frequency, or both, irrespective of the task being performed. It is sometimes referred to as a "quaver." In addition to the perceptual ratings, each patient's voice segments in both postanesthetic and postsurgical condi-
Ofolaryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
IZDEBSKI ET AL
430
tions were measured and expressed in semitones on the musical scale. All speech samples were also assessed for rate, measured in number of syllables per second. The raw data were collated by subject, sex, and experimental conditions, and were analyzed using computer statistics?
RESULTS AND DISCUSSION Perceptual Measurements RELIABILITY Of ,UDGMENTS.- The reliability of perceptual judgments among the five judges for each condition and quality was estimated, using analysis of variance statistics. The summary of the results of these analyses is shown in Table 1. High reliability was obtained for all judges. The lowest reliability was 74% and the highest was 95%. Higher reliability was obtained overall for sustained voice segments than for speech in both conditions.
treatment. For speech, just as for voice, a statistically significant decrease in magnitude of overpressure (p-.OO1) and aperiodicity (P=- .Oll was observed postsurgically for the group. Figure 1 also indicates small but statistically nonsignificant increases in breathiness and tremor postsurgically for the whole group. The presence of overpressure in the postanesthetic condition results from a few subjects included in this study whose RLN was apparently incompletely paralyzed by the injection. In fact, repeated injections of anesthetic are sometimes necessary to paralyze the RlN and achieve any perceived change in voice qualities. As expected, both perceived overpressure and perceived aperiodicity decreased significantly postsurgically. The decrease in overpressure can be explained by a more complete vocal fold paralysis postsurgicalIy, as opposed to the sometimes incomplete chemical paralysis. Postsurgical de-
TABLE 1 MEAN RElIABILITY IN PERCENTAGES DERIVED FROM ANALYSIS OF VARIANCE FOR THE FOUR PERCEPTUAL QUALITIES
CONDITION
PAn" PAn PSut PSu
Voice Speech Voice Speech
BRE"THINESS
OVERPRESSURE
"PERIODICITY
TREMOR
('10)
('10)
('/.)
('!o)
88 85 93 91
91
95
90
90
80 74
84
91 87 93 80
89
°Poslaneslhesia. tPosl5urgery,
VOICE ANDSPEECH CHARACTERISTIC5.-
All Subjects.-Figure 1 shows the presence and the mean ratings of magnitude for the four perceived qualities of voice and speech for all subjects in both postanesthetic and postsurgical conditions. For sustained voice, there was a statistically significant (p • .005l decrease in both the perceived qualities of overpressure and aperiodicity as a result of surgical
crease in aperiodicity 'is most likely explained by the fact that during RLN block, an undesirable spread of anesthesia often occurs, affecting adjacent neural (exterior branch of the superior laryngeal nerve) and muscular tissues, whereas surgical treatment selectively paralyzes one vocal fold, leaving the cricothyroid muscle unaffected. The postanesthetic condition may create short, unstable asymmetry of
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
431
TREATMENT OF SPASTIC DYSPHONIA SPEECH
4
•
BA
....
OP
AP
tween male and female voice quality in the two conditions is difficult to explain and awaits further investigation. INTERSEX MEASURE§,-
TA
Fig l.-Mean magnitude ratings of four qualities: breathiness (BR), overpressure (OP), aperiodidty (AP), and tremor (TR) in voice and speech, comparing postanesthetic (PAn) and postsurgical (PSul conditions for the sampled population. For voice, note statistically significant (55) decrease in OP (p •• OOS) and AP (p • .OOS) in PSu condition. For speech, note the SS decrease in OP (p • .OO1) and in AP (p• .o1) in PSu condition.
vocal fold tension, contributing to aperiodic, chaotic vocal fold vlbratlons.s Furthermore, during this short anesthetic condition, a patient has little time (usually S to 20 minutes) to adjust to the sudden change in vocal fold motility and to learn to exercise full control over vocal tract function. The opposite is evident in the postsurgical condition. Intrasex Differences.-The mean judged magnitude ratings of the four perceptual qualities in postanesthetic and postsurgical conditions for voice and speech were also treated separately by sex. For voice, a statistically significant (P=.05) decrease in overpressure was observed postsurgically in men, while all other changes were not statistically significant. Women showed a statistically significant (P:o:: .01) decrease in overpressure as well as in aperiodicity (pa .D08) postsurgically. Amount of perceived breathiness remained essentially unchanged. For speech, the men showed a statistically significant difference (P- .042) only for increased breathiness in the postsurgical condition. For women, in speech, there was a decrease in the magnitude of all four qualities postsurgically, with three being statistically significant: breathiness (P-.02), overpressure (ps.D01), and aperiodicity (pa .04). The discrepancy be-
Voice.-Figure 2 shows the results of mean ratings of magnitude between men and women for each of the four qualities under postanesthetic and postsurgical conditions for voice. In the postanesthetic condition, a higher magnitude of overpressure (ps.OS) and tremor (pos.001) is observed in female voice than in male voice. In the postsurgical voice condition, there was a statistically significant difference for all four qualities between the two sex groups. The magnitude of overpressure (P=.04) and tremor (pa.D02) was judged to be greater in women than in men. The magnitude of breathiness (P=.003) and aperiodicity (P=.012), on the other hand, was judged to be less in women than in men.
•
_T ANESTHlSlA VOICE
4
i
•
II:
•
~2
l-
OJ
tuIlCIErrt
VOICE
OWl! aPEIUlJ:
4
5'
•,
~
I~ ...... n
1110'
A
T
Fig 2.-Mean magnitude ratings of four voice qualities comparing men and women in PAn and PSu conditions separately. In PAn voice condition, note 55 difference between men and women in OP (p • .OS) and TR (P•.OO1). In PSu voice condition, note SS difference between men and women in all four qualities: BR (P·.OO3), OP (P·.04), AP (P-.012), and TR (P ••OO2).
.' Speech.-Figure 3 shows the results of the mean ratings of magnitude of perceived qualities in speech of men and women in the two conditions. In the postanesthetic condition, a statistically significant (pa .001) intersex difference was observed for tremor, which was more pronounced in women. No other intersex differences were statistically significant. In
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
432
IZDEBSKI ET AL POST ANESTHESIA
SPaCH 4
s
•
~ST
SURGEill'
IPEECH
DMAlE
4
• FEMAlE
.
~3
~2
W
Fig 3.-Mean magnitude ratings of four speech qualities comparing men and women in the PAn and PSu conditions separately. In the PAn speech condition, note the SS difference between men and women in TR (P,. .(01). In PSu speech condition, note SS difference between men and women In BR (P-.001) and in TR (P-.019l.
the postsurgical condition, speech was judged to possess a greater magnitude (P=.01) of tremor in women but a lower magnitude (P=o.OO1) of breathiness than in men. Although no explanation is readily apparent for the male-female differences found, it is likely that they reflect the known anatomic and physiologic laryngeal differences between the adult sex groups.!
Physical Measurements VOCAL FREQUENCY RANGE.-The increased vocal range postoperatively of approximately five semitones for all subjects was significant. The range of voice in men in the postanesthetic condition was 11.9 semitones, and in women, 10.8 semitones. Postsurgically, the voice range was respectively 18.2 and 15.2 semitones for men and women. This postsurgical frequency range expansion of 6.3 semitones for men and 4.4 semitones for women closely approximates normal vocal function in both sex groups. Physiologically, this increase can be explained by the effect of discrete sectioning of the RLN, leaving the function of the cricothyroid muscle intact. Function of this muscle is known to be crucial for control and regulation of vocal range.'o", By contrast, in the postanesthetic condition, the function of the cricothyroid is often impaired
because of the spread of anesthesia to the muscle itself or to the superior laryngeal nerve, with a consequent vocal range reduction, as has been described repeatedly in the literature. 12. ' 5 SPEECH RATE,-In the postanesthetic condition, rate of speech was 4.0 and 3.1 syllables per second for men and women, respectively. In the postsurgical condition, the speech rate for men was 3.6 syllables per second, for women, 3.2 syllables per second. The intrasex group differences between these two conditions were not statistically significant despite some subjects demonstrating speech rate increases postsurgically. Furthermore, the female speech rate was consistently slower than the male speech rate. This intersex difference in speech rate was statistically significant (P= .001) in the postanesthetic and postsurgical conditions (P-.031).
In summary, a statistically significant decrease in overpressure and aperiodicity are observed immediately postsurgically in voice and speech when compared with the postanesthetic condition. The amount of overpressure approaches a zero rating, indicating a near absence of that perceived quality. In general, there are no postsurgical changes in the magnitude of breathiness and tremor if present in the postanesthetic condition. There are no statistically significant changes in the rate of speech for the group between the two conditions; however, a statistically significant increase in vocal range postsurgicalIy was shown by sex and for the entire . group. CONCLUSIONS
The purpose of this study was to compare the voice and speech qualities of male and female patients with spastic dysphonia after lidocaine block and section of the RLN. The goal was to evaluate the usefulness of predicting the quality of immediate post-RLN section phonation
Oto/aryngol Head Neck Surg 87:428-434 (July-Aug) 1979 Downloaded from oto.sagepub.com at East Carolina University on June 5, 2016
TREATMENT OF SPASTIC DYSPHONIA based on the phonatory qualities observed during the chemical RLN block condition. Table 2 summarizes these predictions. The data show that changes occur in all phonatory qualities tested postsurgically when compared with postanesthetic phonation. The magnitude of aperiodicity-which is at times great, and of concern to the patient postanesthetically-decreases significantly postsurgicalIy. Follow-up findings show that residual postsurgical aperiodicity is further reduced by subsequent voice therapy. Although individual male patients may show small increases in the amount of breathiness postsurgically, in general, postanesthetic breathiness is a good predictor of immediate postsurgical breathiness. The amount of breathiness then greatly decreases throughout the first postsurgical year. Overpressure (strain) decreases significantly postsurgically from the postanesthesia condition; therefore, the presence of any overpressure during the anesthesia block condition signals incomplete chemical paralysis. In spite of some individual variations, postanesthetic speech rate and tremor are good predictors of postsurgical performance. Postanesthetic vocal range increases significantly postsurgically; therefore, vocal range is not a good predictor of postsurgical range. It must be understood, however, that the postsurgical increase in vocal range is a most important outcome, as it brings the voice closer to the expected normal function. In general, it appears that voice alone may be used as a test for all the significant changes expected to occur postsurgically. Since intersex differences in voice and speech were shown, however, a less experienced clinician should test both voice and speech. Thus, RLN block for spastic dysphonia is a conservative but an excellent and reliable predictor of the voice and speech qualities expected postsurgically. The improvement in voice and speech in spastic dysphonia patients was
433
'"o~ :x
I-
.~ >
C
QI
C
QI
E 0
~~
