gms | German Medical Science

Introduction: Electromyography (EMG) of the vocalis muscle (TA) alone may not provide sufficient proof for a recurrent laryngeal nerve (RLN) lesion. A PCA-EMG can help in these cases. To get a better understanding of these discrepancies our laryngeal EMG’s were analyzed according to etiology.

Method: Between January 2008 and December 2015 136 patients with a paresis of less than 4 months duration received a laryngeal EMG examination including 67 PCA-EMG’s. 86 paresis were iatrogenic, 40 non-iatrogenic, and 16 related to malignancies along der RLN. EMG’s were evaluated according to proposed guidelines of the ELS working group for neurolaryngology.

Results: In new iatrogenic paresis damage to the TA was less pronounced than in non-iatrogenic paresis. The PCA damage showed no difference between the groups. In 75% of all new iatrogenic we saw a preferential damage of the PCA, only 11.4% were the opposite. In non-iatrogenic paresis this was less pronounced (42.9% preferential PCA damage, 14.3% preferential TA damage).

Conclusions: These resulsts could be explained by a higher mechanical stress for PCA nerve fibers in iatrogenic RLN lesions, a higher vulnerability of PCA nerve fibers or a selective protection of TA by the commonly used intraoperative neuromonitoring. Results should be revalidated in a bigger sample size of a multicenter study, e.g. in form of a European LEMG registry.