The predictors of postoperative laryngeal nerve paresis in patients undergoing thyroid surgery: a pilot study.

OBJECTIVES: The objective of this study was to evaluate the factors predictive of postoperative laryngeal nerve paresis (LNP) in patients undergoing thyroid surgery. We also assess the implications of preoperative LNP on postoperative vocal fold status. STUDY DESIGN: Case series with retrospective chart review. METHODS: Charts of 17 patients who underwent thyroid surgery and had pre- and postoperative laryngeal electromyography (LEMG) were reviewed. LEMGs were ordered routinely in all patients undergoing thyroid surgery, not just in those with clinical findings suggestive of paresis. We collected data relating to pre- and postoperative laryngeal and thyroid evaluations and the details of the surgical procedure. We analyzed the prevalence of preoperative LNP and relationship of thyroid diagnoses, size of thyroid mass, and type of surgery performed with respect to the outcome of the LNP. RESULTS: All the 17 patients had a mild to moderate degree of unilateral or bilateral LNP preoperatively. However, only seven (41.2%) had vocal symptoms. After surgery, only five of these seven patients had voice complaints, and there were no patients with voice complaints among the group that had been asymptomatic preoperatively. Thyroid diagnoses included 11 cases of benign disease (64.7%) in which LNP improved in two, worsened in four, and remained the same in five; and six cases of malignant disease (35.3%) in which LNP improved in none, worsened in two, and remained the same in four. Predictors of worsening postoperative LNP on LEMG included the diagnosis of goiter (P=0.0005) and size of mass greater than 5cm (0.032). CONCLUSIONS: This study supports the notion that there is an intrinsic relationship between benign thyroid diseases and LNP that is probably related to local effects of the disease on the laryngeal nerves. All patients with the postoperative diagnosis of goiter worsened, and all patients with the postoperative diagnosis of adenoma showed no change on postoperative electromyography (EMG). Similarly, all patients with the diagnosis of thyroiditis alone improved, and there were no cases of improvement outside this group. Of the six cases of malignancy, four exhibited no change on EMG and only two worsened. The only reliable predictors of worsening paresis postoperatively are mass size greater than 5cm and diagnosis of goiter.

The prevalence of undiagnosed thyroid disease in patients with symptomatic vocal fold paresis.

OBJECTIVE: Vocal fold paresis has a multifactorial etiology and is idiopathic in many individuals. The incidence of thyroid-related neuropathy in the larynx has not been previously described. The purpose of this study was to evaluate the prevalence of previously undiagnosed thyroid disease in patients with laryngeal neuropathy and to compare this prevalence with that in a cohort of patients with a neurotologic neuropathy. STUDY DESIGN AND SETTING: Case series with chart review; tertiary care, otolaryngology practice. SUBJECTS AND METHODS: Charts of 308 consecutive patients with dysphonia and vocal fold paresis and 333 consecutive patients with sensorineural hearing loss, who presented for evaluation during a 3-year period, were reviewed. RESULTS: One hundred forty-six of 308 (47.4%) patients with vocal fold paresis were diagnosed with concurrent thyroid disease, whereas 55 of 333 (16.5%) patients with sensorineural hearing loss were diagnosed with concurrent thyroid disease (P<0.001, Pearson chi-square = 92.896; degrees of freedom = 5). Thyroid diagnoses among those with vocal fold paresis included benign growths (29.9%), thyroiditis (7.8%), hyperthyroidism (4.5%), hypothyroidism (3.6%), and thyroid malignancy (1.6%). CONCLUSIONS: Thyroid abnormalities are more prevalent in patients with dysphonia and vocal fold paresis than in patients with symptomatic sensorineural hearing loss, suggesting a greater association between previously undiagnosed thyroid abnormalities and laryngeal neuropathy than that between neurotologic neuropathy and thyroid disease.