Diagnostic testing for vocal fold paralysis: survey of practice and evidence-based medicine review

Vocal fold paralysis continues to be a dominant topic in laryngology. Although the majority of cases can be attributed to a known etiology, a significant number of patients present without a clear precipitating event. Over 1,500 studies regarding vocal fold paralysis exist in the medical literature, although only a small percentage report on the use of serum or radiographic testing for the evaluation of idiopathic paralysis. Despite this, patients are routinely subjected to diagnostic evaluation to investigate the underlying cause. To characterize contemporary practice, a national survey of the American Broncho-Esophagological Association (ABEA) membership was undertaken. It is hypothesized that the current practice of diagnostic testing for idiopathic vocal fold paralysis is not well supported by an evidence-based medicine (EBM) review of the available medical literature.

The authors conducted a national survey, systematic EBM review of existing literature.

Surveys were mailed to all active ABEA members; responses regarding practice specialization as well as serum/radiographic diagnostic preferences for idiopathic vocal fold paralysis were tabulated and subjected to statistical analysis. To compare contemporary practice with evidence in the available literature, an EBM review was first performed. Articles for evaluation were selected from a Medline search of English-language abstracts related to adult vocal fold paralysis. The publications were individually reviewed and an EBM level and grade were assigned and compared with the survey results.

Eighty-four of 249 active members responded with 76 (31%) replies submitted for analysis. Specific serum tests were advocated by 41 of 76 (54%) respondents, although the majority (52 of 65 [80%]) felt that they were only "occasionally" or "never" necessary. The most common tests were rheumatoid factor (38%), Lyme titer (36%), erythrocyte sedimentation rate (34%), and antinuclear antibody (33%). Fifty-one of 71(72%) felt that computed tomography (CT) was "always" or "often" necessary and 50 of 72 (69%) replied that chest radiography (CXR) was "always" or "often" necessary. There was no significant difference between CT and CXR ordering (P < .51). In contrast, magnetic resonance imaging (MRI) was described as "always" or "often" necessary in 28 of 71 (39%) of the surveys, significantly less than CT (P < .0001). There was no statistical impact of practice specialization on ordering of serum tests (P = .25) or imaging (P = .50 for CT; P = .46 for CXR; P = .45 for MRI). Following analysis of 1,510 vocal fold paralysis abstracts, 19 publications were found to be appropriate for an EBM review of serum testing with 15 available for review of radiographic imaging. Only one study presented level III evidence; the remainder were levels IV and V comprised of retrospective series and case reports. The evidence supporting serum or radiographic testing toward the evaluation of idiopathic vocal fold paralysis is given an overall grade of "C."

Serum and radiographic testing for the evaluation of vocal fold paralysis is supported by grade "C" evidence only. There are no existing prospective studies estimating the clinical impact of testing on diagnosis or patient outcome. Current practice, as estimated by a survey of the ABEA membership, is not well founded for serum testing and only by retrospective case series with regard to imaging. Further study into the nature of idiopathic vocal fold paralysis and outcomes assessment of diagnostic paradigms may improve clinical practice.