HSC Section 6 Nov2016 Green Book

Paddle et al

fold and supraglottic contraction, pushing rotation of the petiole toward the weakened side, and asymmetric fatigability on repetitive movement. Findings associated with compensa- tory hyperfunction may also be present, including contralat- eral supraglottic contraction, and benign vocal fold lesions such as nodules, polyps, or pseudocysts. 4 On stroboscopy, asymmetry of mucosal wave motion may be the only mani- festation. The diagnostic accuracy of these signs is controver- sial, but when they are identified on nasoendoscopy, along with a suggestive history, a diagnosis of paresis is made. Idiopathic paresis is diagnosed when no cause is found on thorough history and examination. In our clinic, paresis with a history of preceding upper respiratory infection is defined as idiopathic, as there is no definitive test to con- firm causality. Laryngeal electromyography (LEMG) is used as a diagnos- tic and prognostic tool in cases of vocal fold paralysis. There is no consensus on the use of LEMG in the context of vocal fold hypomobility. When performed correctly, LEMG can con- firm the presence and laterality of a neuropathy and identify neuromuscular junction abnormalities and myopathies, as well as ongoing degeneration or regeneration. Some advocates pro- pose that it be employed systematically in paresis, 3 while others use it in situations where the results would alter patient management. 5 Certainly, it does not obviate the role of ima- ging studies in the evaluation of vocal fold paresis. The rationale of imaging in paresis is twofold: First, par- esis may be an early sentinel of an underlying pathology that, where identified, would require further investigation and management in its own right, particularly neoplasia. Second, finding an underlying pathologic process may guide management of the paresis itself. The role of computed tomography (CT) in the evaluation of vocal fold paralysis is well established, given a high overall diagnostic yield (35% to 62%) 6,7 and a high proportion of neoplastic causes (13% to 33%). 8-11 However, its role in the evaluation of paresis is not clearly established, and current practice seems to be extrapolated from the paralysis literature. A single previous study assessed the diagnostic yield of CT in the investiga- tion of paresis. 12 In our institution, CT is performed when there is a clinical diagnosis of paresis but the cause remains ‘‘idiopathic’’ after thorough history and examination—that is, no clear history of preceding nerve injury or other com- pressive or infiltrative lesion and no evidence of a cause on otolaryngologic, neurologic, and chest examination and video endoscopy. Patients may also refuse or strongly desire a CT study. Our study objectives are twofold: first, to establish a diagnostic yield in performing CT in patients with idio- pathic vocal fold paresis; second, to establish a percentage yield of incidental lesions requiring further management in this cohort of patients. This has important clinical, cost, and medicolegal implications. Method This study was approved by the Massachusetts Eye and Ear Infirmary Institutional Review Board. With a precision-based

sample size calculation based on an expected diagnostic yield of approximately 2.0%, 12 an acceptable precision of 1.99%, and a confidence level of 95%, an estimated 191 patients were required. The practice records from January 2004 to January 2014 of 2 senior laryngologists from a single tertiary practice were reviewed. All adult patients were identified who had a clinical diagnosis of idiopathic unilateral vocal fold paresis (IUVFP) and underwent contrast-enhanced CT from skull base to mediastinum. Patients were excluded if they had bilateral vocal fold hypomobility due to the decreased reliability of clinical assessment and the higher likelihood of a central etiology. 13 Patients were also excluded if there was a history of a neurologic diagnosis, such as lar- yngeal dystonia or tremor, myoclonus, parkinsonism, stroke, or other central neurologic process. In each case, a diagnosis of paresis was made by a senior laryngologist, using the above-described symptoms and signs. CT images and reports were reviewed. In each case, any etiology for paresis and any incidental finding were recorded. An etiology for paresis was defined as any lesion along the expected extracranial course of the ipsilateral superior or recurrent laryngeal nerve or vagus, which could be causing pathologic compression, invasion, stretch, or inflammation. An incidental lesion was defined as any clini- cally silent lesion, not associated with the diagnosis of par- esis, but that could lead to further diagnostic or therapeutic intervention. Longitudinal review of files was also undertaken to iden- tify evolution of findings or interval evidence of an etiology for the diagnosed paresis. Due to the evolution in endo- scopic diagnostic criteria for paresis over the 10 years of the study, a sensitivity analysis was performed comparing the mean diagnostic yield of the first 5 years with that of the second 5 years. The null hypothesis of no difference between the means was tested with an unpaired 2-sample t test. Excel 2010 and Stata 10.0 were used for data storage and statistical analysis. Results Patients (n = 237) with unilateral paresis were identified over the period January 2004 to January 2014. Of these, 174 (73%) underwent contrast-enhanced CT scans of skull base to mediastinum and were included in the study. The other 63 (27%) did not undergo CT due to either a clear etiology of their paresis or patient refusal. There was no systematic difference in the demographic characteristics of the CT and non-CT workup patient populations. In the CT workup group of patients, the mean age at diagnosis was 54.5 years (range, 21 to 82). There were a greater proportion of women (56%), while laterality of paresis was evenly distrib- uted, with 51% of lesions being left sided ( Table 1 ). The most common patient symptom was hoarseness. Symptoms of glottic inefficiency were also common, such as vocal fatigue, increased phonatory effort, and decreased projection ( Table 2 ). Patients less commonly complained of loss of range, cough, laryngospasm, globus/dysphagia, and pain.

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