The relationship between the number of parathyroid glands preserved and hypoparathyroidism is not well understood. We sought to determine the number of parathyroid glands that need to be preserved to prevent hypoparathyroidism.

A variety of electromyography (EMG) recording methods were reported during intraoperative neural monitoring (IONM) of recurrent laryngeal nerve (RLN) in thyroid surgery. This study compared two surface recording methods that were obtained by electrodes on endotracheal tube (ET) and thyroid cartilage (TC). This study analyzed 205 RLNs at risk in 110 patients undergoing monitored thyroidectomy. Each patient was intubated with an EMG ET during general anesthesia. A pair of single needle electrode was inserted obliquely into the TC lamina on each side. Standard IONM procedure was routinely followed, and EMG signals recorded by the ET and TC electrodes at each step were compared. In all nerves, evoked laryngeal EMG signals were reliably recorded by the ET and TC electrodes, and showed the same typical waveform and latency. The EMG signals recorded by the TC electrodes showed significantly higher amplitudes and stability compared to those by the ET electrodes. Both recording methods accurately detected 7 partial loss of signal (LOS) and 2 complete LOS events caused by traction stress, but only the ET electrodes falsely detected 3 LOS events caused by ET displacement during surgical manipulation. Two patients with true complete LOS experienced temporary RLN palsy postoperatively. Neither permanent RLN palsy, nor complications from ET or TC electrodes were encountered in this study. Both electrodes are effective and reliable for recording laryngeal EMG signals during monitored thyroidectomy. Compared to ET electrodes, TC electrodes obtain higher and more stable EMG signals as well as fewer false EMG results during IONM.

Background: The indications and extent of cervical lymph node dissection in papillary thyroid carcinoma (PTC) are still being debated. The aim of this study was to analyze the patterns of cervical lymph node metastasis in the lateral and central compartment and related factors and suggest the optimal extent of lateral and central neck dissection for PTC patients with clinical lateral lymph node metastasis.Methods: We retrospectively analyzed 72 patients with unilateral PTC who underwent therapeutic lateral neck dissections with concomitant total thyroidectomy and central neck dissection between January 2001 and December 2009.Results: The 72 patients underwent 79 sides of therapeutic lateral neck dissection. The most frequent metastatic level in the ipsilateral lateral compartment was level IV (75.0%), followed by level III (69.4%), level II (56.9%) and level V (20.8%). Multiple level metastases were common (77.8%) and were correlated with tumor size (≥ 10 mm). The central compartment lymph node metastasis rate was 87.5%, including 26.4% of contralateral central compartment metastases.Conclusion: In PTC patients with clinical lateral lymph node metastasis, the optimal extent of lateral and central neck dissection should include levels II, III, IV and V as well as the bilateral central compartment.