Results of laryngeal nerve monitoring during thyroid operations - Studies and value for clinical practice

Injuries of the laryngeal nerve still remain a source of morbidity for patients undergoing surgery for the thyroid gland. The incidence of permanent damage of the nerve varies from 0.5% to 2.7% depending on the series, but for special thyroid diseases like thyroid carcinoma or goiter recurrence the damage of the recurrent laryngeal nerve could be up to 25%. For that reason several methods of monitoring the movement of the nerve while stimulation have been proposed, Such as inserting a needle into the vocal muscles or working with a surface laryngeal electrode that is attached above the cuff of the tube. For neither of those methods of nerve monitoring severe complications were described. The purchase costs for all the equipment are between 25.000 to 30.000 DM. All the published data regarding monitoring of the laryngeal nerve have been only observation studies with no control group and for that reason the results of the studies could not be obligatory statements. Furthermore not every nerve palsy has been identified by the monitoring of the laryngeal nerve, this method has a sensitivity of less than 70%. Monitoring of the laryngeal nerve is a helpful clinical toot not only for training of surgeons but also during complicated thyroid surgery. Monitoring is especially useful for operations of thyroid carcinoma or revision procedures, But at the moment there is no randomised study available that shows any superiority of this new and expensive method over the standard therapy, therefore further studies are necessary. Until these studies exist the anatomical localisation of the nerve during surgical dissection is still the gold standard.