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Laryngeal Evaluation During the COVID-19 Pandemic: Transcervical Laryngeal Ultrasonography

Julia E. Noel, MD1; Lisa A. Orloff, MD1; Kwang Sung, MD, MS1

1Department of Otolaryngology Head & Neck Surgery Stanford University School of Medicine Stanford, CA 94305

Funding: None Conflicts of Interest: None Author Roles: Noel: Manuscript design/organization, drafting and revisions, figure editing, final approval Orloff: Manuscript conception, manuscript drafting, figure acquisition, final approval Sung: Manuscript conception, manuscript drafting and revisions, final approval

Corresponding Author: Julia E. Noel, MD Department of Otolaryngology Head & Neck Surgery Stanford University School of Medicine 875 Blake Wilbur Drive Stanford, CA 94305 Phone: 650-498-6000 Fax: 650-724-1445 Email: [email protected]

Keywords: Coronavirus, COVID-19, vocal cord paralysis, vocal cord paresis, laryngeal evaluation, laryngeal ultrasound

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Abstract:

The novel coronavirus disease (COVID-19), caused by the SARS-CoV-2 virus, has quickly escalated to become a global pandemic since its initial outbreak in China in late 2019.

Institutions are faced with the challenge of providing the standard of care while maintaining safety for healthcare personnel and patients. Due to the common performance of aerosol generating endoscopic procedures in the upper respiratory tract, otolaryngologists are at uniquely high risk for potential infection. When possible, alternative diagnostic and treatment strategies should be pursued. For patients suspected of having functional laryngeal abnormalities, transcervical laryngeal ultrasound provides a rapid and non-invasive method of evaluation vocal fold motion to inform decisions about safety of feeding, airway, and progression of care.

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1 Since its emergence in Wuhan, China in December 2019, the novel coronavirus has

2 quickly escalated to a global pandemic of unprecedented scale. As of April 2, 2020, it has

3 infected over 1 million people and resulted in more than 50,000 deaths.[1] Healthcare

4 institutions worldwide are faced with the challenge of modifying care to reduce risk of virus

5 transmission to medical personnel and other patients.

6 Through recent publications and unofficial communications, we have learned that

7 physicians in otolaryngology are among the highest risk healthcare personnel during the COVID-

8 19 crisis, likely due to performance of aerosol-generating procedures in the upper respiratory

9 tract.[2] Colleagues in Wuhan have described successful techniques to minimize aerosolization

10 during necessary laryngoscopies and endoscopies. These include ensuring adequate topical

11 anesthesia is delivered on pledgets or via gel instead of by spray, as well as using small

12 diameter scopes to decrease the likelihood of a patient coughing or sneezing during an exam.[2]

13 Appropriate personal protective equipment (PPE) includes a gown, gloves, N95 mask, and face

14 shield.[3] Our group has taken the additional step of requiring that only one (typically the

15 attending) physician be present during such procedures. Though still required for airway

16 concerns, malignancy, or pathology requiring immediate attention, endoscopic exams are

17 otherwise being deferred a minimum of 30 days to protect practitioners and conserve PPE.

18 Since the onset of the pandemic and resultant changes in clinical protocols, we have

19 constantly sought to find balance between necessary care and the safety of patients and

20 healthcare providers. Laryngoscopy has been a particular area of consideration, as it remains

21 one of the most common requests made of otolaryngologists. Though airway may not be at

22 risk, there are many scenarios in which assessment of laryngeal function is necessary to inform

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23 the progression of inpatient care, most commonly for suspected vocal fold paralysis or paresis.

24 These decisions can be critical to increasing bed and, particularly, ICU availability. In addition,

25 among the emergency and oncologic surgeries still taking place, there are patients who will

26 require peri-procedural evaluation of laryngeal function.

27 With this in mind, our institution has implemented a protocol to perform

28 transcutaneous laryngeal ultrasound in place of flexible fiberoptic laryngoscopy when

29 appropriate. Ultrasonography provides a rapid and non-invasive method to assess vocal fold

30 function and can guide decisions about dietary safety and enteral feeding. Perhaps more

31 importantly, in light of the increasing numbers of patients expected to require intubation

32 during this illness, early identification of a vocal fold issue may help avoid an emergency re-

33 intubation. Patient groups in whom this technique is being successfully employed include post-

34 cardiac or thoracic surgery, recent intubation, prior or recent cerebrovascular event, or

35 suspicion based on clinical signs of aspiration and voice change. Pre- or post-operative vocal

36 fold evaluation for thyroid or laryngeal oncologic procedures, and airway evaluation are also

37 possible.

38 Ultrasound assessment of vocal fold mobility has been described fairly extensively in the

39 literature, particularly as it pertains to perioperative evaluation in thyroid and parathyroid

40 surgery. When compared with the gold standard of fiberoptic laryngoscopy, the reported

41 sensitivity and specificity of laryngeal ultrasound in detecting motion abnormalities ranges from

42 53.8-93.3% and 50.5-97.8%, respectively.[4],[5] Concordance with laryngoscopy findings ranges

43 from 70% to upwards of 95%.[4],[6] Adequate visualization can be impacted by gender and age,

44 with older men often being more difficult to image due to shape and calcification of the thyroid

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45 cartilage.[7] Techniques such as viewing from a lateral or longitudinal approach, or using a

46 conductive gel pad, can increase the likelihood of successful visualization.[8],[9]

47 The basic laryngeal ultrasound technique is as follows: a high-frequency “small parts”

48 transducer of 7.5-15 MHz is most commonly used, and the frequency is typically adjusted to the

49 lowest end of the available range, while gain is increased as needed. Patients are typically

50 supine with neck in extension, although the exam can even be performed in the seated patient.

51 The transducer is applied to the skin with ample gel in the midline anterior to the vertical

52 midpoint of the thyroid cartilage or inferior to it angling the transducer slightly superiorly. Some

53 trial-and-error may be necessary to find the optimal imaging plane for any given patient. Vocal

54 fold abduction and adduction are visualized during normal respiration and during breath-

55 holding or Valsalva maneuver. When the patient is asked to stop breathing momentarily, the

56 vocal folds adduct to the midline (Figure 1). When told to resume respiration, vocal fold

57 abduction is noted, confirming bilateral vocal fold mobility (Figure 2). The true vocal folds are

58 typically hypoechoic but may be distinguished in part by a fine hyperechoic line. The false vocal

59 folds are hyperechoic, and the arytenoid cartilages even more so. Even in the unconscious

60 patient, it is possible to evaluate vocal fold mobility during passive breathing with observation

61 of small vocal fold movements with inspiration and expiration. Examination in the midline

62 during phonation is more difficult and less successful, due to gross movement and

63 simultaneous tilting of the thyroid cartilage upon the cricoid cartilage. However, if the vocal

64 folds are not visible from a midline approach due to laryngeal calcification or poor laryngeal

65 contact related to acute angulation of the thyroid alae, then each vocal fold can be assessed

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66 independently from a more lateral perspective. In this case, movement is observed during

67 respiration or better yet during phonation, although symmetry cannot be directly compared.

68 Another advantage of laryngeal ultrasonography is the widespread availability and use

69 of ultrasound technology. Relevant to the current crisis, physicians and healthcare providers in

70 Internal and Emergency Medicine, Anesthesia, and Critical Care have extensive experience

71 using ultrasound for diagnostic purposes and to guide interventional procedures. Even if

72 unfamiliar with laryngeal evaluation, those with basic ultrasound knowledge are able to

73 correctly identify vocal fold immobility without specialized training.[10] This also allows

74 institutions without available otolaryngologists to perform rudimentary laryngeal evaluations.

75 Furthermore, the need for handling and processing of an endoscope potentially contaminated

76 with respiratory secretions, which is known to contain high viral loads, is eliminated.[11],[12]

77 Ultimately, the findings on ultrasound must be considered in the context of the patient’s

78 history and symptoms. In cases where ultrasound is not technically adequate or suspicion for

79 pathology remains high despite an unremarkable scan, laryngoscopy should be discussed in line

80 with institutional guidelines. In our own experience, laryngoscopy is deferred unless

81 intervention would decrease risk of aspiration and/or improve pulmonary toilet in a patient

82 that may be at risk for re-intubation.

83 With each patient encounter, we weigh difficult decisions about disease transmission

84 and upholding the standard of care. Our position as otolaryngologists is unique, as procedures

85 that were once routine now put us at high risk, and must be carefully considered or avoided. As

86 the COVID-19 crisis evolves, there is increasing uncertainty about the duration of impact on the

87 healthcare system, and a resultant need to find safer alternatives to treat our patients.

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88 References:

89 1. COVID-19 Map - Johns Hopkins Coronavirus Resource Center.

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93 Infect. February 2020. doi:10.1016/j.jhin.2020.02.018

94 3. Chan JYK, Wong EWY, Lam W. Practical Aspects of Otolaryngologic Clinical Services

95 During the 2019 Novel Coronavirus Epidemic: An Experience in Hong Kong. JAMA

96 Otolaryngol Head Neck Surg. March 2020. doi:10.1001/jamaoto.2020.0488

97 4. Kandil E, Deniwar A, Noureldine SI, et al. Assessment of Vocal Fold Function Using

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100 5. Wong K-P, Au K-P, Lam S, Lang BH-H. Lessons Learned After 1000 Cases of

101 Transcutaneous Laryngeal Ultrasound (TLUSG) with Laryngoscopic Validation: Is There a

102 Role of TLUSG in Patients Indicated for Laryngoscopic Examination Before

103 Thyroidectomy? Thyroid. 2017;27(1):88-94. doi:10.1089/thy.2016.0407

104 6. Gambardella C, Offi C, Romano RM, et al. Transcutaneous laryngeal ultrasonography: a

105 reliable, non-invasive and inexpensive preoperative method in the evaluation of vocal

106 cords motility—a prospective multicentric analysis on a large series and a literature

107 review. Updates Surg. March 2020. doi:10.1007/s13304-020-00728-3

108 7. Wong K-P, Lang BH-H, Chang Y-K, Wong KC, Chow FC-L. Assessing the Validity of

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110 Matter? Ann Surg Oncol. 2015;22(6):1774-1780. doi:10.1245/s10434-014-4162-z

111 8. Woo J-W, Kim SK, Park I, Choe JH, Kim J-H, Kim JS. A Novel Gel Pad Laryngeal Ultrasound

112 for Vocal Cord Evaluation. Thyroid. 2017;27(4):553-557. doi:10.1089/thy.2016.0402

113 9. Fukuhara T, Donishi R, Matsuda E, Koyama S, Fujiwara K, Takeuchi H. A Novel Lateral

114 Approach to the Assessment of Vocal Cord Movement by Ultrasonography. World J Surg.

115 2018;42(1):130-136. doi:10.1007/s00268-017-4151-z

116 10. Sayyid Z, Vendra V, Meister KD, Krawczeski CD, Speiser NJ, Sidell DR. Application-Based

117 Translaryngeal Ultrasound for the Assessment of Vocal Fold Mobility in Children.

118 Otolaryngol Head Neck Surg. 2019;161(6):1031-1035. doi:10.1177/0194599819877650

119 11. Yu F, Yan L, Wang N, et al. Quantitative Detection and Viral Load Analysis of SARS-CoV-2

120 in Infected Patients. Clin Infect Dis. March 2020. doi:10.1093/cid/ciaa345

121 12. Zou L, Ruan F, Huang M, et al. SARS-CoV-2 Viral Load in Upper Respiratory Specimens of

122 Infected Patients. N Engl J Med. 2020;382(12):1177-1179. doi:10.1056/NEJMc2001737

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Figure Legend:

Figure 1: Transverse view of normal vocal folds during Valsalva (adduction). TVF = true vocal fold. FVF = false vocal fold. White arrow indicates hyperechoic medial margins of true vocal folds meeting in midline.

Figure 2: Transverse view of normal vocal folds during relaxation (abduction). TVF = true vocal fold. FVF = false vocal fold. ARY = arytenoid. White arrows indicate hyperechoic medial margins of true vocal folds.

This manuscript has been accepted for publication in Otolaryngology-Head and Neck Surgery. Figure 1 - Laryngeal adduction Click here to access/download;Figure;USLarynxAddFig1.jpg This manuscript has been accepted for publication in Otolaryngology-Head and Neck Surgery.

This manuscript has been accepted for publication in Otolaryngology-Head and Neck Surgery. Figure 2 - Laryngeal abduction Click here to access/download;Figure;USLarynxAbdFig2.jpg This manuscript has been accepted for publication in Otolaryngology-Head and Neck Surgery.

This manuscript has been accepted for publication in Otolaryngology-Head and Neck Surgery.