2018 Section 6 - Laryngology, Voice Disorders, and Bronchoesophalogy

S INCLAIR ET AL .

Cross-sectional imaging. Cross-sectional imaging for eval- uation of the larynx in thyroid surgery is most useful to assess for laryngeal invasion in cases of proven or sus- pected thyroid malignancy, especially in the setting of preoperative vocal cord paralysis. Cross-sectional imaging does not provide dynamic, real-time images of the larynx, and thus detection of vocal fold paralysis and other laryn- geal motion abnormalities is limited. Radiographic signs of vocal cord paralysis, demonstrable with either CT or MRI, include dilation of the ipsilateral piriform fossa, atrophy of the thyroarytenoid, or posterior crico-arytenoid (PCA) musculature, and vocal fold bowing. These signs should always be correlated with clinical laryngeal exami- nation findings. A recent article reports that the sensitivity and specificity for the detection of VFP by CT are 23% and 100%, respectively. 7 In the setting of thyroid malignancy, the choice of CT versus MRI depends on multiple factors. Although CT with contrast is generally the modality of choice, MRI with contrast often supplements CT findings by further evaluating areas where the superior soft tissue contrast resolution of MRI can be of benefit. For example, an MRI may help confirm a tumor in the fat planes between the strap muscles and the thyroid cartilage and identify tumor involvement of the neurovascular bundles supplying the larynx. MRI is often superior to CT for evaluating esopha- geal or tracheal wall invasion. When evaluating possible tumoral invasion of laryngeal cartilages, both CT and MRI are imperfect but offer complementary information. CT allows for detection of small laminar defects, and abnor- mal hyperdensity may indicate sclerosis from tumoral infil- tration, although heterogeneous laminar mineralization and density of the marrow space may also be physiologically normal. MRI is sensitive to areas of abnormal marrow sig- nal/enhancement within the cartilage, however, abnormal marrow signal in the thyroid cartilage may reflect fibrovas- cular proliferation reactive to adjacent tumor. 42 These diag- nostic pitfalls necessitate consideration of multiple factors in assessing cartilage invasion. CONCLUSIONS When examining the larynx prethyroid and postthyroid surgery, the primary objective is to assess vocal fold function. Although there are many available techniques, flexible transnasal fiber-optic laryngoscopy, by virtue of its availability, rapid learning curve, patient tolerability, and laryngeal diagnostic capabilities is the optimal gold standard currently available technique. Mirror examina- tion may be a useful screening tool when fiber-optic nasal endoscopy is not available. Adjunctive laryngeal examina- tion techniques may be required for patients who exhibit laryngeal symptomatology unaccounted for by findings on fiber-optic nasal endoscopy. RECOMMENDATIONS Preoperative laryngeal examination Preoperative laryngeal examination should be performed on all patients undergoing thyroid surgery who are at high risk for nerve injury (preoperative voice abnormal- ities, history of cervical or upper chest surgery, thyroid

cancer with known posterior extension, or extensive cer- vical node metastases).

Postoperative laryngeal examination

All patients should be considered for postoperative laryngeal examination, particularly where research regarding nerve paralysis is being undertaken. AAO-HNS and ATA guidelines recommend laryngeal examination if postoperative voice abnormalities are present.

Laryngeal examination technique

Flexible transnasal laryngoscopy is the optimal method for laryngeal examination on the basis of widespread availability, patient tolerance, and assessment of both RLN and EBSLN function. Mirror examination of the larynx can adequately docu- ment vocal fold movement abnormalities and is a useful tool in settings where transnasal laryngoscopy is unavailable. Laryngeal ultrasound may be useful for documenting gross vocal fold movement abnormalities, especially in the pediatric population where use of transnasal laryn- goscopy may be limited. Laryngeal stroboscopy should be considered for people with documented postoperative hoarseness who do not have vocal fold movement abnormalities. Acknowledgments The authors thank D. Jarram, M. Mozaffari, Thomas L. Carroll, and Jayme R. Dowdall for their assistance with the indirect (mirror) and stroboscopy sections of this arti- cle, respectively. REFERENCES 1. Jeannon JP, Orabi AA, Bruch GA, Abdalsalam HA, Simo R. Diagnosis of recurrent laryngeal nerve palsy after thyroidectomy: a systematic review. Int J Clin Pract 2009;63:624–629. 2. Francis DO, Pearce EC, Ni S, Garrett CG, Penson DF. Epidemiology of vocal fold paralyses after total thyroidectomy for well-differentiated thy- roid cancer in a Medicare population. Otolaryngol Head Neck Surg 2014; 150:548–557. 3. Musholt TJ, Musholt PB, Garm J, Napiontek U, Keilmann A. Changes of the speaking and singing voice after thyroid or parathyroid surgery. Surgery 2006;140: 978–988; discussion 988–989. 4. Stojadinovic A, Shaha AR, Orlikoff RF, et al. Prospective functional voice assessment in patients undergoing thyroid surgery. Ann Surg 2002;236: 823–832. 5. Rosato L, Carlevato MT, De Toma G, Avenia N. Recurrent laryngeal nerve damage and phonetic modifications after total thyroidectomy: surgical mal- practice only or predictable sequence? World J Surg 2005;29:780–784. 6. Sinagra DL, Montesinos MR, Tacchi VA, et al. Voice changes after thy- roidectomy without recurrent laryngeal nerve injury. J Am Coll Surg 2004; 199:556–560. 7. Randolph GW, Kamani D. The importance of preoperative laryngoscopy in patients undergoing thyroidectomy: voice, vocal cord function, and the pre- operative detection of invasive thyroid malignancy. Surgery 2006;139: 357–362. 8. Farrag TY, Samlan RA, Lin FR, Tufano RP. The utility of evaluating true vocal fold motion before thyroid surgery. Laryngoscope 2006;116:235– 238. 9. Sosa JA, Bowman HM, Tielsch JM, Powe NR, Gordon TA, Udelsman R. The importance of surgeon experience for clinical and economic outcomes from thyroidectomy. Ann Surg 1998;228:320–330.

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