Computed tomography in measuring electrode insertion angle and depth for cricopharyngeal muscle electromyography.

Background: Electromyography of the cricopharyngeal muscle (CP-EMG) is one of many assessment tools for dysphagia. The key to performing EMG and BTX injections is to precisely locate the cricopharyngeal muscle with an electrode. One of the main difficulties of electrode insertion is the fact that the CP muscle is located deep within the neck. Since a neck computed tomography (CT) can clearly display the CP muscle, thyroid, and blood vessels in the neck, we speculate that a safe concentric needle electrode insertion path to the cricopharyngeal muscle can be simulated with the assistance of the patient's neck CT which clearly marks the angle and depth of concentric needle electrode insertion. The purpose of this study was to explore simulated electrode insertion angles and insertion depths for cricopharyngeal electromyography based on retrospective CT data and present a method of percutaneous localization of the cricopharyngeal muscle based on CT images of the neck. Methods: One hundred and forty-three neck CT scans performed between January 2019 and November 2020 were included in this study. With the assistance of the angle and straight-line tools found in the Advantage Workstation 4.4 (GE, HealthCare), simulated insertion angles and depths from the anterior border of the sternocleidomastoid muscle to the cricopharyngeal muscle were obtained. Results: The 143 CT images originated from participants that included 63 males (44.1%) with an average age of 46.2±13.9 years old. The insertion angle, insertion depth, and neck thickness measured on the CT images were 53.2±10.7˚, 24.2±4.1 mm, and 130.1±17.7 mm, respectively. The insertion angle and depth were significantly greater in males than in females (P<0.05), and the insertion angle increased with the age of participants (P<0.05). A generalized linear model (GLM) showed that insertion angle was positively correlated with neck thickness (ß=0.14; 95% CI: 0.03 to 0.25) and gender (ß=5.08; 95% CI: 1.31 to 8.85), and negatively correlated with age (ß=-5.88; 95% CI: -9.54 to -1.62). Insertion depth was only positively correlated with the neck thickness (ß=0.11; 95% CI: 0.07 to 0.15). Conclusions: This study indicates that age, gender, and neck thickness are influencing factors for insertion angle, while neck thickness is the influencing factor for insertion depth. The simulated concentric needle electrode insertion method based on CT can assist clinical operation to ensure safety and effectiveness of cricopharyngeal electromyography.

Force-Bioreactor for Assessing Pharmacological Therapies for Mechanobiological Targets.

Tissue fibrosis is a major health issue that impacts millions of people and is costly to treat. However, few effective anti-fibrotic treatments are available. Due to their central role in fibrotic tissue deposition, fibroblasts and myofibroblasts are the target of many therapeutic strategies centered primarily on either inducing apoptosis or blocking mechanical or biochemical stimulation that leads to excessive collagen production. Part of the development of these drugs for clinical use involves in vitro prescreening. 2D screens, however, are not ideal for discovering mechanobiologically significant compounds that impact functions like force generation and other cell activities related to tissue remodeling that are highly dependent on the conditions of the microenvironment. Thus, higher fidelity models are needed to better simulate in vivo conditions and relate drug activity to quantifiable functional outcomes. To provide guidance on effective drug dosing strategies for mechanoresponsive drugs, we describe a custom force-bioreactor that uses a fibroblast-seeded fibrin gels as a relatively simple mimic of the provisional matrix of a healing wound. As cells generate traction forces, the volume of the gel reduces, and a calibrated and embedded Nitinol wire deflects in proportion to the generated forces over the course of 6 days while overhead images of the gel are acquired hourly. This system is a useful in vitro tool for quantifying myofibroblast dose-dependent responses to candidate biomolecules, such as blebbistatin. Administration of 50 µM blebbistatin reliably reduced fibroblast force generation approximately 40% and lasted at least 40 h, which in turn resulted in qualitatively less collagen production as determined via fluorescent labeling of collagen.

Retest Reliability for Complete Airway Interruption Systems of Aerodynamic Measurement.

INTRODUCTION: Measures of subglottal pressure (Ps), phonation threshold pressure (PTP), and laryngeal resistance (LR) can be used as indicators of vocal cord disorders. The gold standard non-invasive measurement uses labial interruption, which has been shown to have reliability inconsistencies. Mechanical interruption methods have demonstrated promise in measurement reliability. The goal of the present study is to compare retest reliability of labial and mechanical interruption methods. METHODS: 55 subjects aged 18-69 participated. Ten trials were performed for each method. For labial interruption, subjects produced five labial plosives at comfortable and quiet volumes. For mechanical interruption, subjects produced a sustained /α/ while a balloon valve interrupted phonation five times. Thirty subjects completed a second study visit identical to the first approximately two weeks (15 days ± 3.76) after the first visit. Ps, PTP, mean airflow rate, and LR were determined for each subject and retest reliability for each was analyzed. RESULTS: The percent difference in measurement results for test-retest of Ps were 12.88% ± 10.15 for mechanical interruption and 27.56% ± 17.14 for labial interruption (P = 0.0003). The percent difference for PTP measurements were 21.46% ± 16.01 for mechanical and 17.04% ± 14.62 (P = 0.3372) for labial. Intra-subject coefficients of variation of Ps were 0.086 ± 0.046 for mechanical and 0.161 ± 0.078 for labial (P < 0.0001). For PTP, the coefficients were 0.177 ± 0.083 for mechanical and 0.186 ± 0.091 for labial (P = 0.5402). Lastly, for LR (Ps divided by mean airflow rate) the percent differences were 14.33% ± 10.06 for mechanical and 53.87% ± 43.19 for labial (P < 0.0001) with intra-subject variability of 0.115 ± 0.050 for mechanical and 0.287 ± 0.222 for labial (P < 0.0001). CONCLUSIONS: Ps and LR measured using mechanical interruption showed more consistency for both retesting across separate study visits and intra-subject variability. PTP was similar in retesting and intra-subject variability. Continued work to improve mechanical interruption techniques is warranted as these methods offer higher reliability and consistency than the labial interruption methods.

Relationship between short-term and mid-term hearing outcomes after stapedotomy in patients with otosclerosis: an investigation.

BACKGROUND: Although stapedotomy is effective for patients with clinical otosclerosis, the time of hearing stabilization has not yet been consistent. OBJECTIVE: To investigate the relationships between post-operative follow-up times, hearing outcomes, and threshold shift after stapedotomy. MATERIALS AND METHODS: Fifty-five patients with clinical otosclerosis that underwent stapedotomy were retrospectively studied. Pure tone audiometry tests were conducted within the first month (short-term) and within 1 year (mid-term) postoperatively. Data were analyzed for two rounds of audiometry tests at different postoperative follow-up times. RESULTS: Air conduction (AC) and bone conduction (BC) were significantly correlated with preoperative hearing levels (p<.01). AC, BC, and air bone gap (ABG) significantly improved at the short-term (p<.001) and continued to improve at the mid-term (p<.01). The success rate of surgery increased from 87% at short-term to 98% at mid-term. Less than 1/3 of cases encountered BC deterioration at short-term, whereas most improved at mid-term. CONCLUSIONS: Hearing results showed a trend of improvement between short-term and mid-term follow-ups after stapedotomy. AC, ABG, and success rate displayed significant improvement several months postoperatively. BC deterioration occurred in less than 30% of patients at short-term. The recovery of BC at 4 kHz was later than that of low frequencies.

Spectral arc length as a method to quantify pharyngeal high-resolution manometric curve smoothness.

BACKGROUND: Pharyngeal high-resolution manometry (HRM) has emerged over the last decade as a valuable assessment tool for oropharyngeal dysphagia. Data analysis thus far has focused primarily on measures of pressure and duration within key anatomic regions. We apply spectral arc length (SPARC), a dimensionless metric for quantifying smoothness felt to indirectly reflect neuromuscular coordination, as a new method of describing manometric curves. We then use it to distinguish swallows from healthy subjects and those with dysphagia related to stroke. METHODS: Previously collected pharyngeal HRM data from eight subjects with history of stroke and eight age- and sex-matched controls were reviewed. Receiver operating characteristic (ROC) analysis was used to optimize SPARC inputs. SPARC was then computed for the velopharynx, tongue base, hypopharynx, and upper esophageal sphincter (UES), and the values were compared between the two subject groups. RESULTS: Optimized parameter settings yielded an ROC curve with area under the curve (AUC) of 0.953. Mean SPARC values differed between control and stroke subjects for the velopharynx (t = 3.25, p = 0.0058), tongue base (t = 4.77, p = 0.0003), and hypopharynx (t = 2.87, p = 0.0124). Values were similar for the UES (t = 0.43, p = 0.671). CONCLUSIONS: In this preliminary study, SPARC analysis was applied to distinguish control from post-stroke subjects. Considering alternative methods of analyzing pharyngeal HRM data may provide additional insight into the pathophysiology of dysphagia beyond what can be gleaned from measures of pressure and duration alone.

Age and Sex Comparison of Aerodynamic Phonation Measurements Using Noninvasive Assessment.

Purpose The goal of this study was to present vocal aerodynamic measurements from pediatric and adult participant pools. There are a number of anatomical changes involving the larynx and vocal folds that occur as children age and become adults. Data were collected using two methods of noninvasive aerodynamic assessment: mechanical interruption and labial interruption. Method A total of 154 participants aged 4-24 years old took part in this study. Ten trials were performed for both methods of airway interruption. To perform mechanical interruption, participants phonated /α/ for 10 s trials while a balloon valve interrupted phonation 5 times. For labial interruption, participants said /pα/ 5 times at comfortable and quiet volumes. Aerodynamic measures included subglottal pressure, phonation threshold pressure, mean airflow, laryngeal resistance, and others. Results One hundred one participants (51 females) successfully completed testing with both methods. Eight out of 20 measurements were found to have a statistically significant effect of participant age on measurements. Sex alone had a significant effect on vocal efficiency for the labial quiet method. Conclusions The data discussed here can be used to view age and sex trends in vocal aerodynamic measurements. When using either method of mechanical or labial interruption, participant age needs to be taken into account to properly interpret several aerodynamic parameters. A participant's sex is not as important when using these methods.

Simulation of Pediatric Endoscopic Cricoid Reduction and Expansion.

Endoscopic cricoid expansion and reduction are newer approaches to the management of pediatric bilateral vocal fold immobility and postlaryngotracheal reconstruction glottic insufficiency, respectively. These procedures offer a less invasive, endoscopic alternative to procedures that typically required open management with a more prolonged recovery. These technically demanding procedures are currently performed only in select centers, and there is no currently described training model for practicing them. We present a modification to a laryngeal dissection station that allows for simulation of endoscopic cricoid reduction and expansion with excised larynges. The model allows trainees to practice endoscopic posterior cricoid exposure, incision of the cricoid cartilage, placement of a simulated costal cartilage graft for expansion, and endoscopic suturing for reduction. Development of simulators for procedures that are infrequently performed have the potential to help trainees reach surgical competency faster and more safely.

Measurement Reliability of Laryngeal Resistance and Mean Flow Rate in Pediatric Subjects.

OBJECTIVE: Mean flow rate (MFR) and laryngeal resistance (RL) are sensitive to changes in glottal configuration and biomechanics. There is little reported on aerodynamic parameters in children. We conducted a pilot study to evaluate MFR and RL measurement reliability in a pediatric population using labial and mechanical interruption methods. METHOD: Thirty-nine subjects aged 4-17 performed 10 trials per method. For labial interruptions, subjects produced five labial plosives at a comfortable amplitude. For mechanical interruptions, subjects maintained a steady /α/ while a balloon valve interrupted their airflow five times for 250 milliseconds each. MFR was measured as the flow through the interruption device between interruptions. RL was calculated by dividing subglottal pressure (Ps) by MFR. The primary outcome measures of this study were the coefficients of variation of MFR and RL. Paired t tests were used to compare each variable between the two methods. Pearson's correlation was used to analyze the relationship between each parameter and subject age. RESULTS: Mean PS (t(38) = 2.966, P < 0.01) and RL (t(38)=3.563, P < 0.01) were higher for labial interruptions while mean MFR (t(38) = -2.036, P < 0.05) was lower. Intrasubject coefficients of variation were higher for the labial technique for both MFR (t(38) = 4.939, P < 0.001) and RL (t(38) = 3.439, P < 0.01) while there was no difference in PS variability (P = 0.260). Mean MFR and RL were related to age for both the labial (MFR: r = 0.588, P < 0.001; RL: r = -0.468, p = 0.003) and mechanical trials (MFR: r = 0.534, P < 0.001; RL: r = -0.496, P = 0.001). The coefficients of variation for RL were negatively correlated with age for both labial (r = -0.415, P = 0.009) and mechanical trials (r = -0.471, P = 0.002). MFR was only correlated in the labial trials (r = -0.514, P = 0.001) and PS was only correlated in the mechanical trials (r = -0.519, P = 0.001). CONCLUSIONS: Differences in means and intrasubject variation are likely due to differences in task and measurement timing. Precision of MFR and RL measurement in pediatric subjects was higher for mechanical interruption; further exploration of this method and its clinical utility is warranted. Measurement of aerodynamic parameters may be a useful addition to pediatric voice assessment.

Measurement reliability of phonation threshold pressure in pediatric subjects.

OBJECTIVES/HYPOTHESIS: Phonation threshold pressure (PTP), the minimum subglottal pressure (Ps ) required for phonation, is sensitive to changes in laryngeal biomechanics and is often elevated with pathology. Little is reported on PTP in children; challenges with task performance and measurement reliability represent barriers to routine clinical assessment. STUDY DESIGN: Pilot study evaluating PTP and Ps measurement reliability in children using labial and mechanical interruption. METHODS: Twenty-two subjects aged 4 to 17 years (10.7 ± 3.9 years) participated. Ten trials were performed for each method; task order was randomized. For labial interruption, subjects produced /pα/ five times at softest (onset PTP) and comfortable amplitude. For mechanical interruption, subjects produced a sustained /α/ while a balloon valve interrupted phonation five times for 250 ms each; mechanical interruption was performed with a mouthpiece and mask. PTP was recorded as the difference between Ps and supraglottal pressure at phonation cessation (offset PTP). Mean PTP and Ps and intrasubject coefficients of variation were compared. Correlations with age were evaluated. RESULTS: Mean PTP (P < .001) and Ps (P = .005) were higher for labial interruption. Intrasubject coefficients of variation for PTP (P = .554) and Ps (P = .305) were similar across methods. Coefficient of variation was related to age for mechanical-mask trials only (r = -0.628, P = .00175). CONCLUSIONS: Differences in means are likely related to differences in task and PTP hysteresis effect. Reliability is comparable with all methods; using a mouthpiece may be preferable to a mask for mechanical interruption. Measurement of PTP is noninvasive, reliable, and may be a useful adjunct in pediatric voice assessment. LEVEL OF EVIDENCE: 3b Laryngoscope, 129:1520-1526, 2019.