Assessment of Laryngopharyngeal Sensation in Adductor Spasmodic Dysphonia
Phase: NA
Conditions: Spasmodic Dysphonia, Adductor Spasmodic Dysphonia, Voice Disorders
Sponsor: University of California, San Francisco

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Assessment of Laryngopharyngeal Sensation in 
Adductor Spasmodic Dysphonia (SD TT) 
NCT05158179 
Document date: 10/21/21 
PI’s: Yue Ma MD and VyVy Young MD 
 

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Study Protocol and Statistical Analysis Plan  
 
Participant Recruitment 
Subjects with adductor type LD (AdLD) were identified and recruited by advertisements and by 
study clinicians at their institution. Advertisements were physically placed in the UCSF Voice and 
Swallowing Center clinic and were delivered electronically through the website of the National 
Spasmodic Dysphonia Association and to area LD (“spasmodic dysphonia”) support groups.   
Adults greater than 18 years old with AdLD were included if they received a diagnosis 
established by a multi-disciplinary evaluation by a fellowship-trained laryngologist and voice-specialized 
speech-language pathologist. Subjects diagnosed by a physician outside of the study facility were 
evaluated in-person by a fellowship-trained laryngologist to confirm their eligibility for this study. All 
patients were required to have history of favorable response to intra-laryngeal botulinum toxin A (BtxA) 
treatment, as further demonstration of the correct diagnosis of ADLD. This was especially helpful for 
patients initially diagnosed outside of our center. Subjects with abductor or mixed type LD were not 
included in the present study due to their low incidence, but concurrent essential tremor (ET) of the 
vocal tract was accepted.  
Patients were also excluded if they had a history of: concurrent laryngeal diseases or conditions 
other than AdLD+/-ET; bleeding disorder or current anticoagulation use; head and neck radiation; active 
tobacco use; or drinking more than two alcoholic beverages per day. If laryngopharyngeal lesions and/or 
masses, impeding abnormal laryngopharyngeal structure(s), or excessive post-nasal drip were noted on 
laryngoscopy, then examination ceased, and patients were excluded. Prior to testing, subjects also 
completed symptom-specific patient reported outcome measures (PROMs), including: Reflux Symptom 
Index (RSI),18 Voice Handicap Index-10 (VHI-10),19 Dyspnea Index (DI),20 Cough Severity Index (CSI),21 and 
Eating Assessment Tool-10 (EAT-10).22  These PROMs are standardly collected as part of the routine 
clinical are for all patients undergoing evaluation at this center and are reported herein for holistic 

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characterization of these subjects but not intended as a reflection or measure of the severity of their 
AdLD. Lastly, to avoid any potentially confounding physical effects from the injection (e.g., vocal fold 
edema), no testing was performed in the two weeks immediately following BtxA treatment. For patient 
convenience and to facilitate maximal enrollment, patients were allowed to undergo testing at any point 
outside of this post-injection window, although the majority pursued testing immediately prior to a BtxA 
injection on the same day.  
Healthy controls were defined as adults between 18 and 85 years of age without 
laryngopharyngeal disease and were subject to the same screening and exclusion criteria.23 Additionally, 
controls were excluded if they had abnormal patient reported outcome measures (i.e. Reflux Symptom 
Index (RSI) score> 13, Eating Assessment Tool-10 (EAT-10) score>2, or Voice Handicap Index-10 (VHI-10) 
score> 11). 
 
Aesthesiometer Device 
As outlined in previous work, modified nylon monofilaments fixed to the end of 5-French open 
lumen catheters were utilized to deliver tactile stimuli to laryngopharyngeal subsites.12 The Food and 
Drug Administration (FDA) has previously ruled the aesthesiometer to be a Nonsignificant Risk (NSR) 
Device Study (Q190371/S001). Three nylon monofilament sizes (6-0, 5-0, 4-0) were cut to a calibrated 
length of 30 mm to deliver three distinct tactile stimuli of increasing strength, known as buckling-force. 
The 6-0, 5-0, and 4-0 monofilaments deliver an increasing mean force of 0.03 g, 0.11 g, and 0.30 g, 
respectively.12 An intermediary strength “4.5-0” monofilament was created by using a 5-0 monofilament 
of 25mm length, which has been demonstrated to have a mean buckling force of 0.19 g.23  
During testing, the monofilaments were passed through the working channel of a flexible ENF‐
VT2 laryngoscope (Olympus America, Inc., Center Valley, PA) to allow for direct visualization and 
concurrent stimulation of laryngopharyngeal subsites. 

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Laryngopharyngeal Sensory Evaluation 
All subjects underwent a standard protocol for laryngopharyngeal sensory evaluation. This has 
been described in detail previously but briefly reviewed again here.12,13 Prior to testing, subjects were 
screened for any recent changes in conditions affecting voice and swallowing to ascertain subjects-
maintained inclusion criteria. Three investigators executed laryngopharyngeal testing: 1) one to operate 
the laryngoscope; 2) one to maneuver the aesthesiometer monofilament; and 3) one to monitor testing, 
record subjective patient response, and observe cough/gag/swallow responses.  
An investigator then examined both nasal passageways with a nasal speculum, selecting the 
more patent pathway for laryngoscope insertion. The more patent nasal passageway was topically 
anesthetized with cottonoid pledgets soaked in a 50/50 mixture of 4% lidocaine hydrochloride and 
neosynephrine. The cottonoid pledgets were compressed to remove excess liquid to avoid unintentional 
spillage posteriorly to the nasopharynx and potentially larynx, and left in place for five minutes. 
The channeled laryngoscope was then inserted along the inferior meatus towards the posterior 
nasopharyngeal wall. The 6-0 monofilament was pressed against the posterior nasopharyngeal wall and 
swiftly removed to establish a perceptual strength of “1”. If subjects were insensate to this stimulation, 
monofilament size was incrementally increased (i.e., 5-0, 4.5-0, and 4-0) until the stimulus was 
perceived, to establish this internal anchor. As per the validated, standardized protocol, all AdLD 
participants were stimulated on the left, allowing maximal visualization of the vocal folds during testing 
due to camera configuration of the flexible laryngoscope. Only four controls were stimulated on the 
right side, during earliest phases of testing.  
Starting with the 6-0 monofilament, the lateral pyriform sinus (LPS) was presented with the 
planned stimulus, followed by the aryepiglottic fold (AEF) and the false vocal folds (FVF). (Figure 1) 
Participants were instructed to raise their hand when the stimulus was detected, and then were asked 

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by the study team to report a perceptual strength “score,” in comparison to the nasopharyngeal anchor 
strength of 1. LAR response was observed and recorded by the study team. A negative response was 
defined as a lack of LAR to two appropriate stimuli. Gag or cough response to stimuli delivery were also 
recorded, assuming a positive LAR during these observations. 
The LPS and AEF were tested in order of increasing stimulus: 5-0, 4.5-0 and 4-0 monofilaments.  
The false vocal folds (FVF) were tested last, in the same order of increasing monofilament strength. 
Testing of FVF terminated after the first observed LAR given site sensitivity, assuming positive responses 
would also be present for increased monofilament strength.  
 
LAR Assessment 
 
Confirmation of LAR was determined using post-hoc frame-by-frame analysis of video 
recordings. Unilateral or bilateral vocal fold adduction following stimulus delivery was recorded as a 
positive response. Upon review, stimuli were excluded if they did not produce 10-30% monofilament 
buckling (as observed by the reviewer), were entrapped by saliva, or could not compress orthogonally to 
the mucosal surface. Additionally, if line of sight of visualization of vocal fold adduction was obstructed 
or confounded by phonation, the stimuli were excluded. All stimuli were reviewed by one study 
investigator with 30% of stimuli reviewed by a blinded second reviewer. Disagreements were reconciled 
by a blinded third reviewer. 
 
Statistical Methods 
Patient demographics, clinical characteristics, and sensory outcomes were summarized using 
descriptive statistics (means, standard deviations (SD), counts, and percentages). Two-sample Mann-
Whitney and Fisher exact tests were used to compare strength ratings and LAR rates between AdLD and 
control groups at specific sites and filament sizes. To assess predictors of LAR, subjective detection, and 

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gag/cough responses, a mixed-effects logistic regression model was implemented. The unit of analysis 
was binary LAR response (Yes or No) to a tactile stimulus at a specific site with a specific monofilament. 
Univariable and multivariable models included the following fixed effects: tactile force, stimulation site, 
age, gender, and laryngeal dystonia diagnosis (AdLD+/-ET) as five predictors. In the model, a random 
intercept for each subject accommodated correlation of the repeated binary responses within subjects. 
Maximum likelihood estimation was used for model fitting. Odds ratios, 95% confidence intervals, and 
Wald test p-values were reported for logistic regression models. No formal adjustment was made for 
multiple hypothesis testing. In the regression model, the reference levels for the categorical predictors 
were 6-0 for tactile force, LPS for site, male for gender, and control for cohort group. To assess mean 
differences in perceptual strength ratings, linear regression modeling was utilized including the same 
predictors. Stata (Ver 14.1, StataCorp LLC, College Station, TX) was utilized for statistical analysis, with a 
p-value < 0.05 considered statistically significant.   
 
 
 
 
 

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Summary data  
1. Participant Flow (basically a CONSORT flowchart of the number of subjects enrolled, completed, 
not completed, and reason not completed)   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abbreviations: UCSF VSC: University of California San Francisco Voice and Swallowing Center  
 
 
 
 
16 patients with           
AdLD identified 
15 patients with AdLD 
met inclusion criteria and 
initiated testing 
Excluded  
- 
Incorrect diagnosis (n=1)  
o UCSF VSC evaluation not 
consistent with AdLD 
13 patients with AdLD 
met inclusion criteria and 
completed testing, 
representing 117 tactile 
stimuli administered 
Excluded (n=2) 
- 
Subjects requested early 
termination of testing (n=2) 
o Nasal discomfort (n=1)  
o Hyper-reflexive gag 
response to laryngoscope 
(n=1) 
Excluded Stimuli (n=6) 
o Stimulus delivery site not 
reached (n=4) 
o Excessive buckling of 
monofilament (n=1) 
o Larynx not in view for LAR 
assessment (n=1) 
111 total stimuil delivered 
in 13 AdLD patients  

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2. Baseline Characteristics (age, sex, race/ethnicity, other study specific baseline measures) 
Subject 
Sex 
Age 
Concurrent 
Essential 
Tremor 
VHI-10 
at time 
of 
testing 
BtxA 
injection 
location  
Months 
post 
injection 
1 
M 
42 
No 
37 
Unilateral 
9 months 
2 
F 
71 
No 
16 
Bilateral 
3 months 
3 
F 
29 
No 
25 
Unknown 
1 month 
4 
F 
69 
Yes 
7 
Unilateral 
6 months 
5 
F 
62 
No 
18 
Unilateral 
6 months 
6 
M 
68 
No 
15 
Bilateral 
3 months 
7 
M 
45 
No 
24 
Bilateral 
3 months 
8 
F 
84 
Yes 
25 
Unilateral 
24 months 
9 
F 
53 
No 
18 
Unilateral 
4 months 
10 
F 
56 
No 
30 
Bilateral 
3 months 
11 
F 
76 
No 
20 
Unknown 
1 month 
12 
F 
70 
No 
33 
Unilateral 
4 months 
13 
M 
61 
No 
40 
Bilateral 
3 months 
Abbreviations: VHI-10: Voice Handicap Index-10; BtxA: botulinum toxin A  
 
Sixteen subjects with AdLD were identified and recruited; 3 subjects could not complete 
laryngopharyngeal testing. Thirteen total subjects were included in analysis (mean age 60+/-15.2 years, 
9 women). Patient demographics are outlined in Table above. The healthy control cohort comprised 33 
individuals, 36% female (n=12) with a mean age of 52 +/- 18.1 years.  
 
3. Outcome Measures (as specified in the study record) 
 
Primary outcome measure was the presence or absence of the Laryngeal Adductor Reflex (LAR) as 
observed via flexible laryngoscopy. A previously validated, standardized protocol was utilized to 

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stimulate the larynx in 3 distinct anatomic sites (lateral pyriform sinus (LPS), aryepiglottic fold (AEF), and 
false vocal folds (FVF)), with a series of monofilaments of increasing size/force: 6-0, 5-0, 4.5-0 and 4-0 
monofilaments.  
 
Additional outcome measure included subjective perceptual strength rating, as reported by the patient, 
on a scale of 1-10.   
 
4. Adverse Events: none 
 
 
5. Limitations and Caveats 
 
Results of this study showed statistically significant differences in laryngeal responsiveness 
between AdLD and normal cohorts. However, these results may have limited generalizability beyond 
AdLD (i.e., to abductor-type LD, mixed LD, or isolated essential tremor). The impact of concurrent 
essential tremor on results could not be assessed in this small study. This study is also limited by the 
non-randomized nature of testing protocol (although the rationale for this protocol has been described 
previously in the literature) and the unknown effects of BtxA dose or timing on laryngeal sensation 
testing results. Future, prospective, larger-scale, ideally multi-institutional studies are needed to explore 
the findings of this study further.