A PROLONGED VAGAL LATENCY AT THE BEGINNING OF THYROID RESECTIONS PREDICTS AN INCREASED RISK FOR TEMPORARY AND PERMANENT RECURRENT LARYNGEAL NERVE PARESIS

AUTHORS:
F. Wild (Mainz, Germany) , J.I. Staubitz-Vernazza (Mainz, Germany) , A. Lederer (Mainz, Germany) , P.B. Musholt (Mainz, Germany) , T.J. Musholt (Mainz, Germany)
Background:
We hypothesized that - using intraoperative neuromonitoring (IONM) - a "prolonged" vagal latency at the beginning of (hemi)thyroidectomy is associated with an increased risk of recurrent laryngeal nerve (RLN) dysfunction when the patient's body height is taken into account.
Methods:
A single center retrospective data analysis of 1188 datasets for left and 1203 datasets for right thyroid procedures in 1490 patients was carried out. IONM data was merged with the respective clinical datasets recorded in the EUROCINE® registry. Onset latency of the vagus nerve at the beginning of a procedure (V1) was analyzed for a correlation with postoperative RLN paresis. The patient's height and other factors with potential impact on the vagal latency were analyzed to determine the threshold of a "prolonged" latency as indicator of nerve pre-damage.
Results:
A positive correlation between patient body height and the V1 latency was identified. A significant difference of the V1 latency for patients with recorded RLN damage in comparison to patients without nerve damage was discovered (left: p=0.0003951, right: p=0.018). A prolonged left V1 latency is about 2.9 ms longer than the height-adjusted "normal" latency (regression analysis) and is associated with a higher risk of RLN paresis.
Conclusions:
For the first time, it was proven that IONM latency is one of the indicators of an increased risk of RLN paresis in thyroid surgery. A table of "prolonged" left/right vagal latencies in correlation to patient body height is provided, alerting the surgeon to use extra caution or to change the operative strategy.