Continuous Intraoperative Nerve Monitoring in Thyroid Surgery: Can Amplitude Be a Standardized Parameter?

The objective of this study is to evaluate electromyographic waveforms related to vagus monitoring. We collected data from patients undergoing thyroidectomy with CIONM, regardless of vocal cord response amplitude initially measured. We divided data of 193 nerves into three groups, according to initial amplitude value: ≥500 µV (Group 1,110 pt.), between 100 and 500 µV (Group 2, 79 pt.), and <100 µV (Group 3, 4 pt.). ROC curve showed a high diagnostic accuracy of final amplitude absolute value in vocal cord paralysis detection in both groups (89 and 86%). An increase of vocal cord paralysis risk was associated with progressive amplitude reduction (Group 1: OR=1.05, CI=1.02-1.09, p=0.001; Group 2: OR=1.05, CI=1.02-1.08, p=0.002). Cut-off values for amplitude reduction with optimal sensitivity and specificity were -77% in Group 1 and -15% in Group 2. In Group 3 signals showed an amplitude <100 µV for all monitoring, with no loss of a recognizable signal and normal postoperative cordal functionality. The use of a strict amplitude signal cut-off value ≥500 µV could be too restrictive. Also, signal with baseline amplitude <500 µV may be considered equally adequate. Setting the alarm for a reduction of 77% in patients with initial amplitude ≥500 µV and of 15% for those <500 µV could make monitoring safe and an effective aid for surgeons. In conclusion, there are cases in which initial amplitude is lower than that considered as adequate by current literature but with well recognizable and stable EMG waveforms. How those cases should be approached and what should the surgeon's attitude be are a matter of discussion.

High-level expression and efficient purification of recombinant human long pentraxin PTX3 in Chinese hamster ovary cells.

PTX3 is a secreted multimeric glycoprotein which plays a key role in innate immunity by activating the classical complement pathway through specific recognition of the C1q subunit. A method is described for the high level expression of the recombinant human PTX3 in Chinese hamster ovary cells (CHO), adapted to a suspension growth in spinner flasks containing a serum-free chemically defined medium and producing about 50 mg of PTX3/L of culture. A purification procedure to produce a homogeneous protein preparation from the supernatant, by means of anion exchange, hydroxyapatite and size exclusion chromatography, is also reported. This three-step protocol allows us to obtain PTX3 with a recovery yield close to 70%, a purity degree exceeding 95%, and a final host cell protein (HCP) content lower than 150 ppm. The recombinant purified PTX3 retains its biological activity, as demonstrated by C1q binding ELISA assay, and displays a complex quaternary structure characterized by a high secondary structure content quite different from human short pentraxin C-reactive protein (CRP) and serum amyloid P component (SAP), as determined by circular dichroism, fluorescence analysis, and native and SDS-PAGE experiments.