CHANGES OF SONOGRAPHIC, MAGNETIC-RESONANCE TOMOGRAPHIC, ELECTROMYOGRAPHIC, AND HISTOPATHOLOGIC FINDINGS WITHIN A 2-MONTH PERIOD OF EXAMINATIONS AFTER EXPERIMENTAL MUSCLE DENERVATION

This study compares sonographical, histopathological, magnetic resonan ce imaging (MRI), and electromyographical (EMG) findings following acu te muscle denervation, We performed an experimental denervation of the supraspinatus and infraspinatus muscles on 35 New Zealand white rabbi ts by segment resection of the suprascapular nerve. The sonographical appearance of the supraspinatus muscle was followed and documented at short time intervals within a 2-month follow-up period, The sonographi cal, histopathological, and MRI changes due to denervation suggest a r egular pattern, Apart from the reduction of the muscle diameter, there were considerable sonographical signs of denervation with an increase of echointensity and inhomogenicity of echotexture that appeared on d ay 14 after injury, and progressed continuously with time. MRI reveale d a remarkable increase in signal intensity 3 weeks after denervation and reproducible T2 times. Pathological spontaneous activity on EMG co uld also be detected from day 14 after injury Conventional histopathol ogical staining methods (H&E, NADH, ATPase, basic and acid phosphatase ) confirmed denervation and absence of reinnervation. The first nonspe cific histopathological changes were seen 11 days after denervation in the form of moderately atrophic fibers, Typical histopathological sig ns of denervation appeared 3 weeks after nerve dissection. In summary, EMC, ultrasound, MRI, and histopathology each showed first abnormalit ies after about 2 weeks. In addition to EMG, sonography and MRI can do cument the course of muscle atrophy and mesenchymal abnormalities in n eurogenic muscle lesions.