HSC Section 6 Nov2016 Green Book

Simpson et al, Vibratory Asymmetry in Vocal Folds

from our institution before the study period. A retro- spective chart review was carried out for all patients who presented to our clinic during a 3-year period and underwent LEMG for suspected vocal fold pa- resis. Over the study period, 48 patients with suspected VFP underwent diagnostic LEMG. Of those, 23 pa- tients met the study criteria with symptoms of VFP (vocal fatigue or reduced vocal projection) accom- panied by the videostroboscopic findings of bilat- eral normal vocal fold mobility and vibratory asym- metry. The diagnostic LEMG examinations includ- ed an evaluation of the motor unit morphology and recruitment of motor unit potentials (MUPs) for the thyroarytenoid and cricothyroid muscles. Interpre- tation of the LEMG findings was done by a neu- rologist (C.E.J.) who was blinded to the findings of the laryngoscopic examination. In all cases, abnor- mal LEMG findings were considered to be present when there were large-amplitude polyphasic MUPs and incomplete recruitment of MUPs. All abnormal LEMG findings were then classified as left, right, or bilateral, depending on the side of involvement. We did not distinguish between recurrent larynge- al nerve (RLN) and superior laryngeal nerve (SLN) neuropathy for the purposes of this portion of the study. In other words, if the RLN, SLN, or both showed electrophysiological evidence of denerva- tion, the findings were considered “abnormal” for that side. Our endoscopic clinical examination protocol was as follows. All of the patients underwent videostro- boscopy by means of a flexible laryngoscope with a distal chip (Olympus ENF-VQ, Olympus Surgi- cal, Orangeburg, NewYork) rhinolaryngoscope, and most also had rigid laryngoscopy with a 70° rigid endoscope (KayPENTAX, Lincoln Park, New Jer- sey). The patients were instructed to phonate /i/ at low, modal, and high frequencies. When indicated, the technique of “unloading” as described by Kouf- man 8 was also used to help reveal more subtle vibra- tory asymmetry that may have been hidden under compensatory muscle tension patterns. When retrospective evaluation of the endoscop- ic segments was carried out, the following proto- col was used. The best-quality videostroboscopic examination (either flexible or rigid) was used for each case. Of the 48 cases in which LEMG was per- formed for suspected paresis, 23 examinations that were considered to show isolated vibratory asym- metry were selected for the study. The other 25 cas- es, which showed vocal fold immobility, partial im- mobility, videostroboscopic evidence of incomplete closure, or vocal fold lesions, were excluded.

TABLE 1. VOCAL FOLD PARESIS DEMOGRAPHICS AND LEMG FINDINGS Age Cause of (y) Gender Duration LEMG Findings Paresis 62 F 1 y B RLN + SLN Idiopathic 67 F 1 y B RLN Idiopathic 30 M 9 y L RLN + SLN Idiopathic 36 M 36 y B RLN Congenital 28 M 4 mo B RLN Idiopathic 65 M 6 y B RLN + SLN Idiopathic 36 F 10 y B RLN Idiopathic 69 F 2 mo B RLN Idiopathic 35 F 1 y B RLN Idiopathic 36 M 7 y B RLN Idiopathic 44 F 9 y R RLN Idiopathic 29 F 1.5 y L RLN Idiopathic 58 F 9 mo L RLN Idiopathic 37 F 1 y B RLN Idiopathic 51 F 5 y L RLN Idiopathic 43 F 16 mo R RLN Idiopathic 76 M 6 mo B RLN Idiopathic 58 M 14 mo B RLN Idiopathic 54 F 4 mo L SLN Traumatic LEMG — laryngeal electromyography; B — bilateral; RLN — re- current laryngeal nerve paresis; SLN — superior laryngeal nerve pa- resis; L — left; R — right. The videos were edited to include only segments in which the vocal folds were in a fully adducted position and were engaged in vibratory activity. We decided not to show footage of vocal fold mobility, in order to help exclude any possible bias that could occur from interpreting vocal fold movement. The video segments were then randomized and were in- terpreted by three reviewers with extensive experi- ence in videostroboscopic interpretation. Each video segment was reviewed, and the following questions were addressed: 1) Is asymmetry of vibration (am- plitude or mucosal wave) present? 2) If vibration is asymmetric, which side has the increased amplitude and/or mucosal wave? and 3) On which side would you predict the paresis to be present? The LEMG results were used as the gold standard for the diagnosis of VFP. Interpretation of the vid- eostroboscopic findings by our reviewers was then compared to this gold standard to determine the pre- dictive value of subjective vibratory asymmetry on videostroboscopic examination. Results Of the 19 patients with a diagnosis of LEMG-con- firmed VFP (Table 1), the mean patient age was 48.5 years (range, 28 to 76 years). Twelve of the patients were female (63.2%) and had a mean age of 48.8 years, and 7 patients were male (36.8%) and had a mean age of 47 years. The mean time interval from

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