Quantitative and Qualitative Muscular Changes after Selective Neurotomy

Tark, Kwan Chul; Ahn, Seong Joon; Roh, Tai Suk; Park, Beyoung Yun

Abstract

Disfigurement of body contour, caused by excessive muscular hypertrophy, can seldom be effectively and safely corrected by lipectomy, liposuction or combined partial myomectomy. This study was conducted to obtain basic knowledge for the development of a safe and effective method of treating patients with excessive and unwelcome muscle hypertrophy. Accordingly, we developed a new experimental rat model, consisting of the peroneal nerve and its target muscles - the anterolateral crural muscle group. After severance of 1/4, 1/2, and 1/1 of the peroneal nerve, functional parameters based on gross movement and electrophysiologic data were monitored. Changes in the external circumference and weight of the anterolateral crural muscle were documented and compared with control sides. Histologic and histomorphometric parameters of the muscle were also documented. Average takeoff latency in 1/4 and 1/2 neurotomy groups was increased to 130% and 154% of the control at 3 months, and 156% and 149% of control at 6months, respectively. Similarly, average peak-to-peak compound action potentials were 72% and 59% of the control at 3months and 57% and 50% of control at 6months. No definite gait disturbances were evident in the partial neurotomy groups. Maximal circumferences of the anterolateral crural muscle group were significantly reduced to 86%, 71% and 66% of the control in the 1/4, 1/2 and 1/1 neurotomy groups at 3 months (p < 0.001), and to 74%, 68% and 64% of the control at 6 months, respectively (p < 0.001). The corresponding weights were 76%, 62%, and 50% of the control sides at 3 months, and 70%, 56%, and 48% at 6 months in 1/4, 1/2 and 1/1 neurotomy groups. Histograms drawn showing the number of muscle fibers per mm2 in cross-sections, showed a total number of 239 +/- 52 in the control group; the size of muscle fibers was mainly medium to large. The more extensive the neurotomy, the greater the was the number of small angulated muscle fibers, up to a total of 1,564 +/- 211. Although more research work and clinical trials are required, we believe that selective neurotomy has the potential of being an effective tool for reducing muscle bulk, and avoiding apparent muscular dysfunction and complications.