Vocal cord paresis and paralysis after thyroid and parathyroid surgery

BACKGROUND . Vocal cord paresis in 59% of cases is a result of surgical interventions on the organs of the neck and chest. However, thyroid surgery is the main cause of them (up to 49% of cases). Unfortunately, the most tragic complication — bilateral recurrent laryngeal nerve injury in 80% is associated with thyroidectomy. AIM . To determine the risk factors and causes of vocal cord paresis in patients after thyroid and parathyroid surgery. To analyze the clinical picture, catamnesis of postoperative vocal cord paresis. MATERIALS AND METHODS . The study included patients who underwent thyroid and parathyroid surgery. Laryngeal mobility was assessed in all patients before and after surgery (transcutaneous ultrasound, videolaryngoscopy). Surgical interventions were performed by 8 endocrine surgeons with mandatory visualization of the recurrent laryngeal nerve. In the late postoperative period videolaryngoscopy was performed in patients with vocal cord paresis every month. Patients monitoring was discontinued upon recovery of laryngeal mobility. RESULTS . In the study identified 2682 (100%) recurrent laryngeal nerves and diagnosed 169 (6.3%) unilateral vocal cord paresis. Preoperative vocal cord paresis (type A) was found in 0.5% of patients. Postoperative vocal cord paresis due to carcinoma invasion (type B) were noted in 0.5% of cases. Type “C” included inadvertent postoperative vocal cord paresis, occurring in 5.3% of cases. Factors such as sex, age, disease, chronic thyroiditis, increasing surgery, retrosternal location, and increased volume of the thyroid lobe did not elevate the level of postoperative vocal cord paresis (p>0.05). However, reoperation, progression of malignant processes and surgical technique influence the number of postoperative vocal cord paresis (p < 0.05). Vocal cord paresis was characterized by the following clinical properties: negative Valsalva test — 68.1%, choke on liquid — 46.0%, breathlessness — 7.4%, and the voice did not change in 24.5% of patients. Recovery of laryngeal mobility was observed in 67.2% of patients. In 97.1% of cases complete recovery of motor function was noted within the first 3 months after surgery. CONCLUSION . The clinical picture of vocal cord paresis in the early postoperative period ranging from asymptomatic forms to dysphagia and respiratory failure. Moreover, the symptoms and laryngoscopic findings are nonspecific (independent of the cause of recurrent laryngeal nerve injury), thus, not determining the prognosis for recovery of laryngeal mobility. However, in the long-term postoperative period indicators such as frequency of recovery, timing of recovery and volume of vocal cord mobility reflect three types of nerve damage — neurotmesis, neuropraxia, and axonotmesis.