Thyroarytenoid-lateral Cricoarytenoid Muscle Complex Research Articles

Quantitative laryngeal electromyography (LEMG) in unilateral vocal fold paralysis: Developing normative values using the opposite normal mobile vocal fold

ObjectiveLaryngeal electromyography (LEMG) is used to confirm neuropathy; traditionally, it is evaluated qualitatively. This study aimed to develop normative values for the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex by determining the mean turns (MT) and mean amplitudes (MA) using the opposite normal mobile vocal fold in unilateral vocal fold paralysis (VFP). This study also compared the MT and MA of the paralyzed vocal fold with that of the normal side and analyzed their correlations. MethodsThis is a cross-sectional study in which 77 patients (18 males, 59 females, mean age of 48) with unilateral VFP with an opposite normal mobile vocal fold underwent LEMG with a standardized protocol. Koufman gradings and MT and MA were used for the qualitative and quantitative evaluations. Mann–Whitney U test was performed to compare the median of the turns and amplitudes between the opposite normal mobile vocal fold and the paralyzed side. A linear-scale graphical “cloud” of the normal TA-LCA muscle complex was generated using logarithmic regression analysis. The qualitative and quantitative parameters were analyzed using multiple analysis of variance and Kruskall–Wallis test. Post-hoc analysis was performed to further determine the differences of the significance between both parameters. The correlation between the qualitative and quantitative parameters was analyzed using Spearman correlation. ResultsThe MT and MA were significantly higher for the normal TA-LCA muscle complex than the paralyzed side (582 vs. 336; 412 vs. 296, respectively) and the median of the turns and amplitudes were significantly lower in the paralyzed side with p-values <0.001. A significant difference was observed between the Koufman grading and the combination of MT and MA [F (8,144) = 73.254] and between the Koufman grading and MT and MA individually [H (4, 72) = 18.3 and H (4, 72) =33.4], in which both had p-values <0.001. A moderate negative linear relationship was seen between the Koufman grading and MT and MA. On further analysis, it was revealed that only certain pairs of Koufman grading were statistical significant. ConclusionsThis study was the first to present the quantitative normative values and “cloud” of the TA-LCA muscle complex using the opposite normal mobile vocal fold in patients with unilateral VFP in which it is comparable to healthy controls. We concluded that quantitative LEMG supports the qualitative Koufman grading method however it cannot be used independently to determine the severity of neuropathy.

Quantitative laryngeal electromyography parameters may correlate with improved outcomes following botulinum toxin injection for spasmodic dysphonia

Despite use of qualitative laryngeal electromyography (LEMG) guided botulinum toxin A (BoNT-A) injection for treatment of adductor spasmodic dysphonia (AdSD), unsatisfactory injections and complete "misses" remain problematic. We aimed to determine if the quantitative LEMG measure of number of small segments (NSS) correlates with voice outcomes following (BoNT-A injection for AdSD. Automated quantitative LEMG analysis was performed during electromyography (EMG) -guided BoNT-A injection into the thyroarytenoid-lateral cricoarytenoid muscle complex for treatment of AdSD. Pre-injection phonatory NSS values were correlated with clinical voice outcomes and patient reported injection results. Quantitative LEMG measures were obtained for 45 AdSD patients (28 female, mean age 60.8 ± 12.8 years) during EMG-guided BoNT-A injection. Mean sampled NSS during phonation immediately prior to BoNT-A injection was 524 ± 323 (range: 2-904). Mean follow up was 36.5 ± 9.4 days; one patient was lost to follow-up. In comparison to their previous BoNT-A injection, the current injection was rated as worse, same, and better by 13 (29.5%), 25 (56.8%), and 6 (13.6%) patients, respectively. All 4 (9.1%) patients with NSS < 200 rated their BoNT-A injection result as worse than previous, and change in Voice Handicap Index-10 (VHI-10) scores were worse or without change. Aiming for an NSS value greater than 200 during phonation prior to BoNT-A toxin injection for AdSD may reduce unfavorable voice outcomes.

Abnormal Laryngeal Electromyography Findings in Asymptomatic Adults Across the Age Spectrum.

Laryngeal electromyography (LEMG) is a diagnostic tool for patients with suspected neurogenic abnormalities of the larynx. LEMG is often used with the assumption that any abnormality is symptom-/disease-related. We sought to determine the prevalence of abnormal LEMG findings in a group of healthy asymptomatic adults across a large age spectrum. Open, prospective study, gender-match and age balanced by decade. Forty-six healthy participants (age 20-78) underwent LEMG, including 178 muscles. Participants had no history of voice problems, normal VHI-10, and normal flexible laryngoscopy. Qualitative and quantitative LEMG (bilateral) were performed involving the thyroarytenoid-lateral cricoarytenoid muscle complex (TA-LCA) and cricothyroid (CT) muscles. LEMG parameters included evaluation for fibrillation potentials, sharp waves, reduced recruitment, polyphasic potentials, electrical synkinesis, and measurement of turns per second. Of participants, 4% had at least one abnormal qualitative finding (slightly reduced recruitment or two to three discrete polyphasic potentials). There were no findings of fibrillation potentials or sharp waves. There were no abnormal qualitative findings in the CT muscles tested. Of participants, 16% had at least one abnormal synkinesis finding. LEMG qualitative abnormalities and quantitative abnormalities do not appear to correlate with gender or age. Abnormal qualitative and quantitative LEMG findings were uncommon and minor in severity in our group of asymptomatic healthy adults. The likelihood of abnormal LEMG results in asymptomatic adults was 2.2% for qualitative findings, 9.3% for synkinesis, and 5.4% for turns/s. 3 Laryngoscope, 131:2065-2069, 2021.

Low-Dose LEMG-Guided Botulinum Toxin Type A Injection for Intractable Vocal Process Granulomas

Vocal process granuloma (VPG) has a varied treatment success rate and may frustrate patients and physicians due to poor outcomes. There is still a lack of standard protocols to manage VPG. This study aimed to review the efficiency of a standardized low-dose laryngeal electromyographic (LEMG)-guided botulinum toxin A (BTA) injection in intractable vocal granulomas. Twenty-four patients with intractable VPG were recruited. All patients underwent percutaneous LEMG-guided BTA injection on the thyroarytenoid-lateral cricoarytenoid muscle complex in an office setting. The injecting dose was standardized to 1 U in 0.1 mL normal saline at a time. We evaluated the treatment effect by measuring the lesion size with serial laryngoscope evaluations. The postinjection follow-up time varied from 3 to 23 months. Twenty-one patients (87.5%) experienced complete regression of the granuloma over 1-7 months (median 3 months). No major adverse effects were noted during the follow-up period. For recalcitrant VPG, LEMG-guided low-dose BTA injection has the potential to be a safe, efficient, and effective treatment.

The impact of cricothyroid involvement on adductor recovery in unilateral vocal fold paralysis.

Wide variation in postinjury functional recovery is a hallmark of unilateral vocal fold paralysis (UVFP), ranging from zero to full recovery. The present study examined the impact of cricothyroid (CT) muscle involvement on recovery using quantitative laryngeal electromyography (LEMG) of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex at multiple times postinjury. Prospective cohort study in a medical center. Eighty-one patients with UVFP (37 males and 44 females) received an initial assessment of quantitative LEMG, stroboscope, acoustic voice analysis and 36-Item Short Form Survey quality-of-life questionnaire at 3 to 6 months after UVFP onset and a follow-up assessment at 12 months after UVFP onset. The initial and follow-up assessments were performed at 4.3 ± 1.9 and 12.5 ± 1.3 months after UVFP onset, respectively. The peak turn frequency of the TA-LCA muscle complex on the lesion side was improved at the follow-up (470 ± 294 Hz) compared with the initial assessment (300 ± 204 Hz) (P < .001). Patients were also divided into two groups with (n = 27) and without (n = 54) CT involvement, respectively. TA-LCA muscle complex turn frequency improved in patients without CT involvement (from 277 ± 198 to 511 ± 301 Hz; P < .001), but not in those with CT involvement (from 345 ± 211 to 386 ± 265 Hz; P = .46). Seventy-one of all patients received early intervention with intracordal hyaluronate injection, showing similar therapeutic effects in those with and without CT involvement. Acute UVFP with combined TA-LCA muscle complex and CT muscle involvement has a poor prognosis, with poorer recovery of TA-LCA muscle complex recruitment. Early interventions should be considered in patients with UVFP with CT involvement. 2 Laryngoscope, 130:139-145, 2020.

Voice Range Change After Injection Laryngoplasty for Unilateral Vocal Fold Paralysis

Patients with unilateral vocal fold paralysis (UVFP) caused by nerve injury manifest with voice changes. This study investigated vocal performance measured by voice range profile (VRP) in patients with UVFP and changes in VRP in response to intracordal hyaluronate injection. Eighty-five patients with UVFP were enrolled prospectively, among whom 68 received intracordal hyaluronate injections. The outcome measurements included VRP, acoustic and aerodynamic analyses, peak turn frequency of thyroarytenoid-lateral cricoarytenoid muscle complex (TA-LCA) measured by laryngeal electromyography, and normalized glottal gap area by videolaryngostroboscopy. The peak turn frequency of the paralyzed TA-LCA showed a modest correlation with max fundamental frequency (F0) and F0 range. Closed-phase normalized glottal gap area showed modest negative correlations with max F0 and F0 semitone range. Regarding conventional acoustic and aerodynamic analyses, the paralyzed TA-LCA peak turn frequency was only correlated with maximal phonation time. Intracordal hyaluronate injection improved VRP performance by increasing max F0, decreasing min F0, increasing F0 range, and increasing semitone range (all P <0.01) with small or medium strength of effect size (Cohen d, 0.39-0.76). Change in voice pitch in patients with UVFP can partly predict impairment of neuromuscular functions and glottal gap. VRP provides a more sensitive reflection of the severity of neuromuscular impairment, compared with conventional voice analysis. The validity of VRP is further supported by a robust response to voice improvements following injection laryngoplasty.

Effect of intralaryngeal muscle synkinesis on perception of voice handicap in patients with unilateral vocal fold paralysis.

Intralaryngeal muscle synkinesis associated with unilateral vocal fold paralysis (UVFP) is thought to preserve thyroarytenoid-lateral cricoarytenoid muscle complex tone, resulting in a better voice despite the presence of vocal fold paralysis (VFP). This study compares voice handicap in patients with unilateral VFP (UVFP) with and without evidence of adductory synkinesis on laryngeal electromyography (LEMG). Retrospective review of LEMG data and Voice Handicap Index-10 (VHI-10) scores of patients diagnosed with permanent UVFP. LEMG was performed within 1 to 6 months post onset of UVFP. Patients were stratified into two groups: 1) recurrent laryngeal nerve (RLN) neuropathy with synkinesis and 2) RLN neuropathy without synkinesis. Synkinesis was diagnosed when the sniff to phonation maximum amplitude ratio was ≥0.65. VHI-10 scores at 6-month follow-up were recorded. Four hundred forty-nine patients with UVFP and who had an LEMG were reviewed. Eighty-three patients met the inclusion criteria, with 16 in group 1 and 67 in group 2. There was no significant difference between the groups with regard to age, timing of LEMG from onset of VFP, number of patients undergoing temporary vocal fold injection or use of off-label nimodipine. Average VHI-10 scores at 6 months post onset of VFP were 14.4 ± 10.6 for patients with LEMG-identified synkinesis (group 1) and 21.0 ± 10.1 for patients with no LEMG evidence of synkinesis (group 2). This was statistically significant (P = .02). Patients with unilateral vocal fold paralysis and LEMG evidence of laryngeal synkinesis are more likely to have less perceived voice handicap than those without synkinesis. 4. Laryngoscope, 127:1628-1632, 2017.

Disease Characteristics and Electromyographic Findings of Nonsurgery-Related Unilateral Vocal Fold Paralysis.

The detailed characteristics and prognosis of nonsurgery-related unilateral vocal fold paralysis (NSUVFP) are currently unclear. This study evaluated the extent of laryngeal nerve lesions and the individual characteristics for patients with NSUVFP. Retrospective, case series. Patients with unilateral vocal fold paralysis (UVFP) were evaluated using videolaryngostroboscopy and quantitative laryngeal electromyography. The side of nerve lesions, involvement of the external branch of the superior laryngeal nerve (eSLN), and complete vocal fold motion recovery were evaluated after ≥ 6 month follow-up. A total of 207 UVFP patients were recruited, including 153 surgery-related UVFP and 54 NSUVFP patients. Thirty-four (63%) and 20 (37%) NSUVFP patients were further assigned to idiopathic and nonsurgery-related-nonidiopathic (NSNI) groups, respectively. In the idiopathic group, eSLN lesions occurred in all six (100%) patients with right-side paralysis, but in only six of 28 (21%) patients with left-side paralysis (P < 0.001). The turn frequency of the paralyzed thyroarytenoid-lateral cricoarytenoid muscle complex is lower in the NSNI group (333.1 ± 192.1) compared with the idiopathic group (490.2 ± 255.1) (P = 0.02). The probability of complete vocal fold motion recovery did not differ among groups (P > 0.05). Idiopathic and NSNI UVFP have different clinical presentations defined by laryngeal electromyography. NSNI UVFP had more severe denervation changes compared with idiopathic UVFP. These results may support two pathogenic mechanisms for idiopathic UVFP: 1) neuropathy specifically involving left recurrent laryngeal nerve (RLN), and 2) neuropathy affecting nerves proximal to the RLN. 4. Laryngoscope, 127:1381-1387, 2017.

Quantitative electromyographic characteristics of idiopathic unilateral vocal fold paralysis.

Unilateral vocal fold paralysis with no preceding causes is diagnosed as idiopathic unilateral vocal fold paralysis. However, comprehensive guidelines for evaluating the defining characteristics of idiopathic unilateral vocal fold paralysis are still lacking. In the present study, we hypothesized that idiopathic unilateral vocal fold paralysis may have different clinical and neurologic characteristics from unilateral vocal fold paralysis caused by surgical trauma. Retrospective, case series study. Patients with unilateral vocal fold paralysis were evaluated using quantitative laryngeal electromyography, videolaryngostroboscopy, voice acoustic analysis, the Voice Outcome Survey, and the Short Form-36 Health Survey quality-of-life questionnaire. Patients with idiopathic and iatrogenic vocal fold paralysis were compared. A total of 124 patients were recruited. Of those, 17 with no definite identified causes after evaluation and follow-up were assigned to the idiopathic group. The remaining 107 patients with surgery-induced vocal fold paralysis were assigned to the iatrogenic group. Patients in the idiopathic group had higher recruitment of the thyroarytenoid-lateral cricoarytenoid muscle complex and better quality of life compared with the iatrogenic group. Idiopathic unilateral vocal fold paralysis has a distinct clinical presentation, with relatively minor denervation changes in the involved laryngeal muscles, and less impact on quality of life compared with iatrogenic vocal fold paralysis. 4. Laryngoscope, 126:E362-E368, 2016.

Cricothyroid muscle dysfunction impairs vocal fold vibration in unilateral vocal fold paralysis

The relevance of the cricothyroid (CT) muscle in patients with unilateral vocal fold paralysis (UVFP) remains controversial. To clarify the functional significance of the CT muscle in patients with UVFP, the confounding effect of the severity of recurrent laryngeal nerve injury should be taken into consideration. In the present study, quantitative laryngeal electromyography (LEMG) was used to measure the severity of paralysis of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex to allow the functional contribution of the CT muscle to be determined. Cross-sectional study performed in an otolaryngology outpatient clinic. Thirty-one patients with a main diagnosis of UVFP were recruited. The main outcome measures included LEMG examination, quantitative LEMG analysis of the TA-LCA muscle complex, UVFP-related quality-of-life questionnaire (Voice Outcome Survey [VOS]), voice acoustics analysis, videolaryngostroboscopy, and general quality-of-life questionnaire (Short Form-36 Health Survey [SF-36]) assessments. The vocal cord position did not differ between patients with and without CT muscle impairment. Patients with both TA-LCA and CT paralysis showed poorer vocal fold vibration (P = .048) and higher fundamental frequency (P = .02), and the VOS and SF-36 were both poorer compared with patients with only TA-LCA paralysis. Although the vocal cord position was not influenced by CT muscle function, coexisting CT muscle paralysis may damage the voice by impairing vocal fold vibration in UVFP patients.

In vivo oxygen consumption and hemoglobin levels in human thyroarytenoid muscle

Visible light spectroscopy (VLS) is the technology behind the Food and Drug Administration-approved TSTAT device that is used to monitor tissue oxygen (StO(2)) and relative total hemoglobin (rtHb) levels by measuring reflected visible light. The purpose of this novel, pilot study was to determine if VLS is a reliable and valid method of measuring StO(2) and rtHb levels in the human thyroarytenoid/lateral cricoarytenoid (TA-LCA) muscle complex, thus providing information about vocal fold muscle physiology. Pre-test/post-test with mulitple baselines and two conditions. VLS measurements were taken at baseline, during exercise, and following recovery on six subjects using both noncontact channel-port endoscope (endo-probe) and laryngeal electromyography (LEMG) needle-guided techniques. The average baseline StO(2) was 69% (standard deviation [SD] = 3.6%) for the LEMG-guided probe and was 71.5% (SD = 2.8%) for the endo-probe. During phonation, the StO(2) for the LEMG-guided probe dropped to 59% (SD = 7%; P = .04). Mean rtHb measured by the LEMG probe rose from a baseline of 144 μM (SD = 165 μM) to 214 μM (SD = 166 μM, P = .34) during phonation and back to 149 μM (SD = 139 μM, P = .85) after recovery. Mean rtHb as measured using the endo-probe at baseline and after recovery was 104 μM (SD = 30 μM, P = .76). VLS can be used to measure changes in StO(2) and rtHb levels pre- and postexercise in the human TA-LCA muscle complex.

Quantitative laryngeal electromyography: Turns and amplitude analysis

Laryngeal electromyography (LEMG) is primarily a qualitative examination, with no standardized approach to interpretation. The objectives of our study were to establish quantitative norms for motor unit recruitment in controls and to compare with interference pattern analysis in patients with unilateral vocal fold paralysis (VFP). Retrospective case-control study We performed LEMG of the thyroarytenoid-lateral cricoarytenoid muscle complex (TA-LCA) in 21 controls and 16 patients with unilateral VFP. Our standardized protocol used a concentric needle electrode with subjects performing variable force TA-LCA contraction. To quantify the interference pattern density, we measured turns and mean amplitude per turn for ≥10 epochs (each 500 milliseconds). Logarithmic regression analysis between amplitude and turns was used to calculate slope and intercept. Standard deviation was calculated to further define the confidence interval, enabling generation of a linear-scale graphical "cloud" of activity containing ≥90% of data points for controls and patients. Median age of controls and patients was similar (50.7 vs. 48.5 years). In controls, TA-LCA amplitude with variable contraction ranged from 145-1112 μV, and regression analysis comparing mean amplitude per turn to root-mean-square amplitude demonstrated high correlation (R = 0.82). In controls performing variable contraction, median turns per second was significantly higher compared to patients (450 vs. 290, P = .002). We first present interference pattern analysis in the TA-LCA in healthy adults and patients with unilateral VFP. Our findings indicate that motor unit recruitment can be quantitatively measured within the TA-LCA. Additionally, patients with unilateral VFP had significantly reduced turns when compared with controls.