The incidence of vocal fold motion impairment after primary thyroid and parathyroid surgery for a single high-volume academic surgeon determined by pre- and immediate post-operative fiberoptic laryngoscopy

Abstract

Background: Vocal fold motion impairment (VFMI) is a well-recognized complication of thyroid and parathyroid surgery. Preoperative counseling requires a thorough understanding of the incidence, risk factors, and value of early diagnosis of postoperative VFMI. Our objective is to describe the incidence of and risk factors for VFMI for a single high-volume academic surgeon, and to assess the utility of immediate postoperative fiberoptic laryngoscopy (FOL) in early diagnosis of VFMI.

Methods: Retrospective cohort study of patients undergoing primary thyroid and parathyroid procedures by a single high-volume surgeon at an academic tertiary care center. All patients underwent preoperative and immediate postoperative FOL. The primary outcome was incidence of VFMI, either temporary (<1 year) or permanent (1 year or more). The unit of analysis was number of recurrent laryngeal nerves (RLN) at risk. Risk factors for VFMI were analyzed using logistic regression, reporting unadjusted and adjusted odds ratios (OR and aOR) and 95% confidence intervals (CI).

Results: The study population comprised 1547 patients undergoing 1580 procedures for a total of 2527 nerves at risk, excluding the 27 nerves found to have motion impairment on preoperative FOL. Sixty-seven new incidents of VFMI were identified on postoperative FOL, with an additional six new incidents detected after voice complaints prompted FOL upon follow-up. Thus, the incidence of postoperative VFMI was 2.9% of RLNs at risk (73 of 2527). The sensitivity and negative predictive value of immediate postoperative FOL were 92% and 99.8% respectively. Permanent VFMI occurred in 9 cases (0.4%), 3 of which were from intentional RLN transection for malignancy. Odds of VFMI were significantly lower after parathyroidectomy (aOR = 0.1, 95%CI = 0.01-0.8 compared with hemithryoidectomy) and higher with central neck dissection (aOR = 2.4, 95CI = 1.0-5.9). Among cases of malignancy, odds of VFMI increased significantly with increasing T-stage (adjusted p_trend<0.001).

Conclusion: VFMI is rare and usually temporary after primary thyroid and parathyroid procedures, with increased risk associated with larger primary malignancies and the inclusion of central neck dissection. Immediate postoperative FOL is useful for early detection of VFMI that may allow for clear definition of temporary and permanent immobility rehabilitation especially if there is evidence to support early intervention.

Keywords: Complications; Hoarseness; Laryngoscopy; Palsy; Parathyroidectomy; Paresis; Recurrent laryngeal nerve; Thyroidectomy; Vocal fold paralysis.