Spector J G, Lee P
Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, Missouri 63110, USA.
Ann Otol Rhinol Laryngol. 1998 Feb;107(2):141-8. doi: 10.1177/000348949810700210.
The minimum number of regenerating facial nerve myelinated motor axons that are required to innervate and activate the mimetic musculature is not known. We compare rabbit facial nerve regeneration following complete transectional injuries of the buccal division to the evoked and behavioral muscle activities of the quadratus labii superioris muscle of the rabbit in three experimental models: end-to-end direct anastomosis (N = 4), 8-mm autologous nerve grafts (N = 8), and 10-mm silicone chamber implants (N = 40). Data are presented as total numbers of regenerating myelinated axons that traverse the surgical repair and innervate the fascicles of the transected distal nerve stump, as well as the percentage of regenerating neurites, as compared to the preoperative normal controls. Five weeks after neural repair, direct end-to-end anastomosis regained more myelinated axons across the reconstructed defect (2,632 +/- 1,232; 67%) than silicone tube implants (2,006 +/- 445; 51%) or autologous cable graft repairs (1,660 +/- 1,169; 42%). However, only a small percentage of myelinated fibers innervated the intrafascicular region of the distal transected neural stump in direct anastomosis (948 +/- 168; 24%), silicone tube implants (670 +/- 275; 17%), or autologous nerve grafts (445 +/- 120; 12%) in rabbits that regained evoked and behavioral mimetic muscle activity. All rabbits with direct anastomosis and neural cable grafts regained motor activity, despite the fact that 66% of regenerating motor neurites in cable graft repairs and 54% in direct anastomosis were collateral sprouts that did not contribute to effective muscle activity. In 17 rabbits with neural regenerates within the silicone tube implants that did not regain mimetic activity, the mean number of regenerating myelinated motor axons across the defect was 504 +/- 419 (13%), and the mean number of axons that innervated the distal transected nerve stump fascicles was 277 +/- 128 (7%). Therefore, the minimal number of motor axons that is required to activate the quadratus labii superioris muscle is 12% of the original motor axon population of the normal buccal nerve division.
支配并激活表情肌所需的再生面神经有髓运动轴突的最小数量尚不清楚。我们在三种实验模型中比较了兔颊支完全横断损伤后面神经的再生情况与兔上唇方肌的诱发肌肉活动和行为肌肉活动：端端直接吻合术（N = 4）、8毫米自体神经移植（N = 8）和10毫米硅胶室植入（N = 40）。数据以穿过手术修复部位并支配横断远端神经残端束的再生有髓轴突总数呈现，以及与术前正常对照相比的再生神经突百分比。神经修复后5周，端端直接吻合术在重建缺损处恢复的有髓轴突比硅胶管植入（2,006 +/- 445；51%）或自体电缆移植修复（1,660 +/- 1,169；42%）更多（2,632 +/- 1,232；67%）。然而，在恢复诱发和行为表情肌活动的兔中，在直接吻合术（948 +/- 168；24%）、硅胶管植入（670 +/- 275；17%）或自体神经移植（445 +/- 120；12%）中，只有一小部分有髓纤维支配远端横断神经残端的束内区域。所有接受直接吻合术和神经电缆移植的兔都恢复了运动活动，尽管在电缆移植修复中66%的再生运动神经突和在直接吻合术中54%的再生运动神经突是侧支芽，对有效的肌肉活动没有贡献。在17只硅胶管植入内有神经再生但未恢复表情活动的兔中，穿过缺损处再生有髓运动轴突的平均数量为504 +/- 419（13%），支配远端横断神经残端束的轴突平均数量为277 +/- 128（7%）。因此，激活上唇方肌所需的运动轴突的最小数量是正常颊神经分支原始运动轴突数量的12%。
