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Outcomes of Botulinum Toxin Treatment for Patients With Spasmodic Dysphonia
Michael S. Benninger, MD;
Glendon Gardner, MD;
Cynthia Grywalski, CCC-SLP
Arch Otolaryngol Head Neck Surg. 2001;127:1083-1085.
ABSTRACT
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Background Spasmodic dysphonia (SD) is a focal dystonia of the larynx. Although
individuals with SD have variable degrees of difficulty in everyday communication
and speaking, many report significant impairments. The impact of SD on the
quality of life of people with the disorder has not been well measured.
Objectives To assess the impact of SD using a voice-specific, validated outcomes
instrument, the Voice Handicap Index (VHI), and to evaluate the effect of
botulinum toxin treatment on quality of life.
Methods The VHI measures 3 subscales (physical, functional, and emotional) of
impact of a voice disorder as well as a total impact score. The VHI was completed
by 30 consecutive patients with SD before receiving botulinum toxin injection
and 2 to 4 weeks after injection. Pretreatment scores on the VHI were compared
with posttreatment scores.
Results Pretreatment scores on the VHI showed significant impairment in all
3 subscales (physical, 25.5; functional, 21.4; and emotional, 20.4) and the
total score (67.6). Statistically significant improvements occurred in all
3 subscale scores and the total score (P = .001)
for the 22 patients who completed the posttreatment survey.
Conclusions Spasmodic dysphonia has a significant impact on patients' perception
of quality of life as measured by the VHI. Significant improvements in all
3 subscale scores and the total score on the VHI occur after treatment with
botulinum toxin.
INTRODUCTION
SPASMODIC dysphonia (SD) is a focal dystonia of the larynx with characteristic
interruptions in voice and visible true and false vocal fold spasms when the
larynx is visualized during running speech. Spasmodic dysphonia spasms can
result in forceful adduction of the vocal folds during phonation (adductor
SD), abduction (abductor SD), or both adduction and abduction during phonation
(mixed SD). Adductor SD is much more common than abductor SD, accounting for
about 80% of cases. A familial association has been identified in some cases
with the isolation of a specific gene in these clusterings.1
Many treatments have been advocated for SD, including voice therapy,2 recurrent laryngeal nerve section,3-4
laryngeal framework surgery,5 and selective
denervation. Over the past decade, the treatment of choice for most patients
has been botulinum toxin injections into the muscles of the larynx. This temporarily
weakens or paralyzes these muscles, which reduces or eliminates the spasms.
The procedure is simple and easily accomplished in the office setting, and
has had predictably good results.
Several studies have attempted to show the efficacy of botulinum toxin
injections through a variety of objective and subjective tests.6-9
Blitzer and Brin9 used a scale of 0% (no voice
or full disability) to 100% (normal voice) to assess patients' responses to
treatment and found that a mean rating of 90% was attained following injection.
Murray et al8 used the State-Trait Anxiety
Inventory, the Self-rating of Depression Scale, and the Somatic Complaints
Checklist to evaluate patients before and after treatment with botulinum toxin.
Scores on these tests refelected significant improvement both 1 week and 2
months after injection. Aronson et al7 also
showed a significant improvement in patients' self-ratings of voice after
injections, but found that the course of voice change was not predictable,
uniform, or equal among patients. Truong et al10
found that patients who received botulinum toxin injections had significant
improvement in their perception of voice and in their treatment team's overall
ratings of speech and specific vocal characteristics.
Laboratory evaluations have also been used to assess the impact of botulinum
toxin treatment for SD. Zwirner et al6 evaluated
acoustic measures, mean airflow rates, and videolaryngoscopic findings 1 week
before injection and 1 week and 1 month after treatment. They found that mean
airflow rates and videolaryngoscopic findings returned nearly to normal at
1 month after treatment. They also noted significant improvements in acoustic
parameters, although abnormal characteristics remained.6
There has been a recent effort to evaluate a patient's perception of
outcome to an intervention through objective, validated, patient-focused outcomes
instruments. In 1997, Jacobson et al11 reported
their development and validation of the Voice Handicap Index (VHI). The VHI
is a 30-question instrument that objectively evaluates the physical, emotional,
and functional impact of voice disorders and their treatment. It has been
used to assess the impact of a number of voice disorders, including dysphonia
caused by vocal fold paralysis, mass lesions, functional disorders, edema,
and neurologic disorders (including SD).12
Since there is no generally agreed-upon objective test to serve as a "gold
standard" for the assessment of voice disorders, the VHI may serve as a key
tool in assessing the impact of the disorder on patients' quality of life
and evaluating the outcome of treatment.
The purpose of this study was to assess the outcome of botulinum toxin
treatment for SD from the patients' perspectives using the VHI as the objective
tool.
PATIENTS AND METHODS
Thirty consecutive patients treated with botulinum toxin injection for
adductor SD in the Department of Otolaryngology–Head and Neck Surgery
at Henry Ford Hospital, Detroit, Mich, were asked to participate in the study.
The diagnosis of SD was made through a thorough history and characteristic
perceptual voice analysis, confirmed by flexible laryngoscopy showing intermittent
episodes of spasm that occurred during running speech. Characteristic quality
of voice was determined by both a voice-language pathologist and a laryngologist.
The VHI is used routinely in the Henry Ford Hospital voice clinics to
assess the impact of the voice disorder and the response to treatment. The
30-item VHI asks questions in 3 domains: physical, functional, and emotional,
using a 5-point equally appearing scale (never, almost never, sometimes, almost
always, always). The maximum score is 120. An 18-point change in pretreatment
to posttreatment total scores or an 8-point change in scores for each domain
is considered statistically significant.11
All patients completed the VHI before injection and were sent home with a
follow-up VHI and self-addressed envelope to be returned at the time of their
perception of maximal benefit, which was typically 1 to 3 weeks after injection.
Patients were also asked to rate their voice as normal, mildly, moderately,
or severely affected. If no follow-up questionnaire was returned, the patient
was contacted and a second form was sent. Ten of the 30 patients were being
treated for the first time.
The VHI was evaluated on patients with SD before and after treatment
with botulinum toxin. The change in index due to treatment was evaluated with
a paired t test. The 3 subscales of the VHI—functional,
physical, and emotional—were also evaluated with paired t tests. The set of 3 P values were evaluated
for significance using the Hochberg13 method
for multiple comparisons. This ensured a family-wise P
value of .05. A secondary analysis comparing the changes observed in the VHI
total and subscale measures by patient sex was also examined using 2-sample t tests. The Hochberg method was again used to evaluate
the 3 subscale P values.
RESULTS
Of the 30 patients who completed the initial evaluation, 22 completed
the posttreatment questionnaire. There were 24 women and 6 men in the study,
with 17 women and 5 men completing the posttreatment survey. There were no
sex differences. Seven of the 10 patients being treated for the first time
and 13 of the 20 previously treated patients completed the posttreatment questionnaire;
there was no statistical difference between these groups. The ages of the
patients were stratified by decade: 20 to 29 years, 1 patient; 30 to 39 years,
4 patients; 40 to 49 years, 9 patients; 50-59 years, 10 patients; 60 to 69
years, 3 patients; and 70 to 79 years, 3 patients. The mean age was 51 years.
When stratified by age, there was no statistical difference in performance
of the survey by decade or when comparing patients 49 years or younger with
those 50 years or older.
The responses of the 30 patients on the pretreatment survey and the
22 patients on the posttreatment survey are noted in Table 1. The mean pretreatment total score was 67.6 (range, 36-101).
The mean posttreatment total score was 22.0 (range, of 1-44).
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Table 1. Patient Responses on Voice Handicap Index Before and After
Treatment
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The difference between the pretreatment and posttreatment scores for
the 3 subscales and total scale are noted in Table 2. The 22 patients who completed both surveys showed significant
improvements (decreases in scores) in all 3 subscales of the VHI and in the
total score. The physical subscale score decreased by 17.8 points, the most
of the 3 subscales. The total score declined 46.3 points. This decrease is
highly significantly different from zero, and is also significantly different
from a decrease of 18, which is the specified clinically significant decrease
originally reported in validating the VHI.11
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Table 2. Differences in Voice Handicap Index Scores Before and After
Botulinum Toxin Injection (n = 22)
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The 22 patients with pretreatment and posttreatment information on the
self-evaluation rating all showed improvement. The 18 moderately affected
patients reported improvement to mild dysfunction (n = 8) and normal function
(n = 10). The 4 who were severely affected reported improvement to mild (n
= 1) and normal (n = 3). Of the 8 patients who did not complete the posttreatment
survey, 4 rated their impairment as severe and 4 as moderate.
COMMENT
Voice disorders have been shown to significantly impact the quality
of life of the individuals who experience them. Using the Medical Outcomes
Trust 36-Item Short Form General Health Survey, it was found that individuals
with various voice disorders had worse perception of quality of life in 6
of the 8 domains (physical functioning, role functioning due to physical limitation,
vitality, social functioning, mental health, and role functioning due to emotional
limitation), compared with the general population.12
In a study12 of heterogeneous population
of patients with masses, edema, paralysis, and neurogenic causes of dysphonia,
mean VHI scores were 14 for the emotional, 14 for the functional, and 21 for
the physical subscales. The mean total score was 48. Patients with vocal fold
paralysis had the worst (highest) total mean score (51), while patients with
edema had the best (lowest) mean score (35).12
In the present study, patients with adductor SD had worse scores (mean, 67.6)
than both the heterogeneous group of dysphonic patients and even the paralysis
group. This would suggest that patients with SD perceive that they have a
significant disability from their disorder, which has a substantial negative
impact on their perception of quality of life, even as it relates to other
voice disorders. The physical symptom scores were worse than the functional
and emotional scores, which also mirrors what is seen in the other voice disorders.12
There were no detectable differences in VHI scores or the difference
between pretreatment and posttreatment scores for patients who were being
treated for the first time with botulinum toxin compared with those who were
having a subsequent injection.
The fundamental question asked in this study was whether patients with
SD perceive that there is an improvement in quality of life after treatment
with botulinum toxin. There were statistically significant changes in the
total scores on the VHI in relationship to zero and to the prior established
norms of a significant change of 18 points.11
In addition, there were significant differences between the pretreatment and
posttreatment subscale scores in comparison to zero and the previously established
norms of 8 for each subscale. The physical subscale difference was greater
than that of the emotional and functional subscales. Changes in scores were
not different between the women and men in our study group.
These findings support the effectiveness of botulinum toxin in the treatment
of patients with SD and are consistent with other studies that have used different
parameters to evaluate this treatment's effectiveness.6-9
Our findings showed substantial variation in initial score and the change
in score following treatment among patients. This finding was also noted by
Aronson et al,7 who used patient self-ratings
of voice and phonatory effort after botulinum injection. In our 22 patients
who completed the posttreatment survey, 13 perceived that their voices were
normal and 9 believed that they had only a mild impairment, while none perceived
that they had moderate or severe dysfunction. This is in contrast to 18 patients
who perceived that they had a moderate dsyfunction and 4 who reported having
a severe voice problem before injection.
In conclusion, patients with adductor SD have significant disability
as measured by the VHI in the physical, functional, and emotional subscales
and total scores. This is true whether or not they had been previously injected
with botulinum toxin. Their VHI scores are worse than those in a heterogeneous
cohort of patients with voice disorders, including paralysis, benign masses,
and edema. Significant improvements in patient perception of quality of life
occur after injection with botulinum toxin. Botulinum toxin injections are
effective in improving patients' perceptions of dysfunction.
AUTHOR INFORMATION
Accepted for publication February 9, 2001.
Corresponding author and reprints: Michael S. Benninger, MD, Department
of Otolaryngology–Head and Neck Surgery, Henry Ford Hospital, 2799 W
Grand Blvd, Detroit, MI 48202 (e-mail: Mbenning{at}HFHS.org).
From the Department of Otolaryngology–Head and Neck Surgery (Drs
Benninger and Gardner) and the Division of Speech-Language Sciences and Disorders
(Ms Grywalski), Henry Ford Hospital, Detroit, Mich.
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