Study of electron microscopical structure and taste function of regenerated chorda tympani nerve after severance during middle ear surgery

1. 中耳手术切除鼓索神经后，将近端残端与远端残端在颞肌筋膜上不缝合吻合。即使造成神经间隙缺损，近端和远端切割端几乎在原始位置放置在颞肌筋膜上，没有神经移植。在中耳胆脂瘤二期手术中，重建鼓膜粘膜下层可见再生神经。1 .鼓室索神经再生发生率为46%（33/71）。33例再生鼓室索神经患者中，61%（20/33）恢复味觉功能。另外87例中耳手术中耳索神经切断的患者中，有24%（21/87）的味觉功能恢复。二期术中发现鼓室索神经再生，味觉功能恢复的病例，用数码显微镜观察菌类乳头的分布和大小，并将其形态记录在存储卡上。真菌状乳头分布分为三组。(1)舌部两侧乳头分布无明显差异。双方在分配上有差异。(3)舌断侧真菌状乳头完全退化。35例味觉功能恢复的患者，1组31%，2组69%。另一方面，味觉功能未恢复的87例患者中，61%归为2组，39%归为3组。这些结果表明，中耳鼓索神经断裂后，鼓索神经在中耳再生，这些再生的神经纤维到达真菌状乳头，重新获得味觉功能。少

1. Method of nerve repair and incidence of regenerated chorda tympani nerveAfter the chorda tympani nerve was severed during middle ear surgery, the proximal and distal stumps were anastomosed without suture on the temporal muscle fascia. Even if a nerve gap defect was created, the proximal and distal cut ends were placed on the temporal muscle fascia almost in the original position without nerve graft. During the second stage surgery of middle ear cholesteatoma, regenerated nerve was detected in submucosal layer of the reconstructed eardrum. Incidence of regenerated chorda tympani nerve was 46% (33/71 cases).2. Functional result using electrogustometry and filter-paper disk method after severance of the nerveIn 33 cases with regenerated chorda tympani nerve, 61% (20/33 cases) had taste function. In other 87 cases whose chorda tympani nerves were severed during middle ear surgery, 24% (21/87 cases) showed recovery of taste function in eather electrogutometry or filter-paper disk method … More .3. Morphological study of fungiform papillae (distribution and size)In cases in which regeneration of the chorda tympani nerve was detected during the second stage of the surgery and taste function recovered, distribution and size of the fungiform papillae were observed using digital microscopy and their morphology was recorded in memory card. Distribution of the fungiform papillae was divided into three groups. (1)There was no difference in distribution of papillae between both sides on the tongue. (2)There is a difference in distribution between both sides. (3)The fungiform papillae was completely degenerated on the severed side of the tongue. In 35 cases whose taste function recovered after severance of the nerve, 31% was included in group 1 and 69% was in group 2. On the other hand, in 87 cases in which taste function did not recover, 61% was included in group 2 and 39% was in group 3.These results indicate that, after severance of the chorda tympani nerve, the chorda tympani nerve regenerate in the middle ear and these regenerated nerve fibers reach to fungiform papillae and re-obtained taste function. Less