Electromyography does not show adequate effectiveness in diagnosis of suprascapular nerve lesions caused by rotator cuff tear in rat model.

Abstract

Background: Suprascapular nerve lesions caused by rotator cuff tears have been widely reported. However, the accuracy of electromyography as a definitive diagnostic method for nerve lesions is controversial. This study aims to evaluate the diagnostic effectiveness of electromyography for nerve lesions following varying degrees of rotator cuff tears in rat models.

Methods: Twenty rats underwent bilateral rotator cuff tenotomy and were divided into four groups to simulate clinically relevant rotator cuff tears of different sizes. The supraspinatus tendon free ends in three groups were sutured at the tendon insertion site, the humeral head midpoint, and the coracoid process base. The fourth group underwent free retraction following supraspinatus and infraspinatus tendon transection. Nerve lesion incidence was assessed using in vivo electromyography under anesthesia and Neurofilament-Heavy immunofluorescence staining of the suprascapular nerve after sacrifice at 2 weeks postoperatively.

Result: The area under the receiver operating characteristic curve (AUC) for both single and combined electromyography indicators of nerve entrapment was < 0.7, indicating low diagnostic effectiveness. Immunofluorescence staining revealed a statistically significant positive correlation between nerve lesion incidence and tear size.

Discussion: Although widely used clinically, electromyography lacks sufficient diagnostic accuracy for suprascapular nerve lesions following rotator cuff tears. This underscores the need for surgeons to carefully evaluate suprascapular nerve integrity in such cases.