Complication Risk in Secondary Thyroid Surgery

Secondary thyroid surgery is rare, compared with primary thyroid surgery. However, secondary surgery has a greater risk of complications due to the formation of scar tissue as well as increased fragility of the tissues following the previous surgery. Several surgical techniques and strategies have been recommended to decrease the complication rate associated with secondary surgery. The aim of this study was to evaluate the complication rate in patients who underwent secondary thyroid surgery using a lateral approach and intraoperative nerve monitoring (IONM).

The data of 44 patients who underwent secondary surgical intervention after thyroid surgery performed for benign or malignant thyroid disease (Group 1), and of 44 patients who underwent primary surgery (Group 2) were compared. Lobectomy patients with a histopathological result of malignant disease, whom were applied completion thyroidectomy were excluded from the study. Secondary surgery was performed using a lateral approach. Access was achieved between the anterior edge of the sternocleidomastoid muscle and the strap muscles. In primary surgery, the thyroid lodge was entered through the midline. Standard IONM was applied in all cases. Hypocalcemia was defined as a serum calcium level of ≤8 mg/dL within the first postoperative 48 hours, regardless of clinical symptoms. Transient and permanent recurrent laryngeal nerve paralysis was evaluated based on the number of nerves at risk. The lobectomy was considered to be high-risk with the presence of recurrence, Graves' disease, substernal goiter, and application of central dissection.

The mean age of Group 1 and 2 was 49.9±14.1 years and 45±12.6 years , respectively (range: 22-90 years; p=0.69). Female patients constituted 90.9% (n=40) of the population in Group 1 and 75% (n=33) of the patient population in Group 2 (p=0.87). In Group 1, 11 (25%) patients, and 7 (15.9%) patients in Group 2 underwent surgical intervention due to the presence of a malignant disease (p=0.29). Bilateral intervention was applied in 26 (59.1%) patients in Group 1 and 28 (63.6%) patients in Group 2. The rate of transient and permanent hypocalcemia in Groups 1 and 2 was 34.1% (n=15) vs 22.5%, and 2.5% (n=1) vs 0%, respectively, without any significant intergroup difference (p=0.237, p=1). In Group 1, 71 lobes were operated on, and there were 72 in Group 2. All of the interventions in Group 1 (100%), and 31.9% (n=23) of those in Group 2 were high-risk, and there was a significant intergroup difference (p<0.0001). The rate of transient and permanent vocal cord paralysis were 4.2% (n=3) vs 2.8% (n=2) and 6.9 % (n=5) vs 0% in Groups 1 and 2, respectively (p=0.719; p=0.245).

When performed with a meticulous and attentive technique, secondary surgical intervention can be applied without increasing the incidence of permanent complications. Though there is substantial risk associated with all of these procedures, the rate of vocal cord paralysis was similar to that seen after primary intervention, and was thought to be related to surgical experience and technique, as well as the use of IONM.