Risk factors for permanent laryngeal nerve paralysis in patients with thyroid carcinoma.

OBJECTIVES: This study investigated the incidence of and risk factors for permanent recurrent laryngeal nerve paralysis for patients with thyroid malignancy.

DESIGN: Retrospective chart review.

SETTING: Tertiary oncology referral centre.

PARTICIPANTS: Records of 290 consecutive patients treated between 1997 and 2001 were reviewed. All patients who have had one or more operations. Patients with preoperative recurrent laryngeal nerve paralysis and patients who underwent thyroidectomy in conjunction with laryngectomy were excluded. The incidence of postoperative permanent cord palsy was calculated in relation to the number of patients.

MAIN OUTCOME MEASURES: Age, gender, thyroid functions, tumour localisations and size, multicentricity, thyroid capsule invasion, extrathyroidal soft tissue invasion, differentiation, histological type, co-existence of lymphocytic thyroiditis, total number of dissected and metastatic nodes, type of surgery, the place of surgery and number of operations were the risk factors investigated for permanent recurrent laryngeal nerve paralysis. Univariate and multivariate analyses were performed.

RESULTS: Permanent recurrent laryngeal nerve paralysis developed in 27 (9%) of 290 patients with thyroid carcinoma. Transient and permanent paralysis rates in total or subtotal thyroidectomy, completion thyroidectomy and neck dissection groups were 5/3%, 7/3% and 24/17% respectively. Cox regression analysis identified the type of surgery [adjusted relative risk (RR) = 2.1, 95% confidence interval (CI) = 1.1-4.0, P = 0.01], extrathyroidal soft tissue invasion (RR = 5.7, 95% CI = 2.0-15.7, P = 0.001) and number of metastatic nodes (RR = 1.6, 95% CI = 1.1-2.5 P = 0.01).

CONCLUSIONS: The factors related with recurrent laryngeal nerve paralysis post-thyroid carcinoma surgery are linked to special features of the tumour and to the type of surgery.