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BACKGROUND: In facial reanimation surgery, higher donor facial nerve axonal load yields a superior outcome. Nerves supplying the zygomaticus major muscle are primary donors for the grafting procedure; however, their topography has not been studied in detail. This study identified potential donor nerves by quantifying axon loads of the zygomaticus major muscle through histological analysis of cadaveric specimens. MATERIALS AND METHODS: Forty-three hemifaces from 26 fresh human cadavers were studied. Branching patterns of nerves were classified according to their shapes. All branches of interest were sectioned and stained for an axon count. The potential donors were mapped into each tributary of nerves supplying the zygomaticus major. RESULTS: Branching patterns were categorized into five types: Y-type (28%), X-type (28%), H-type (19%), E-type (14%), and F-type (11%). The mean number of axons in the most superiorly and proximally located main branches was 1387.33 ± 406.59 in Y-type, 1021.42 ± 187.79 in X-type, 1222.75 ± 193.82 in H-type, 1496.17 ± 364.567 in E-type, and 1353.40 ± 256.07 in F-type (P > 0.05). A topographic relation between facial nerves supplying the zygomaticus major muscle and their mean axonal load was illustrated. The zygomatic/buccal branches were found within 5 mm from Zuker's point in 100% of X-, Y-, H-, and E-type and 75% of F-type specimens. CONCLUSIONS: Most proximal facial nerve branches supplying the zygomaticus major, arising at the anterior border of a parotid gland, contained over 900 axons in all five branching types. The primary subbranches may be used in selected cases if donor weakness is a concern. Further, our study provides evidence that demonstrates the precision of Zuker's point.

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OBJECTIVE: p38 member of mitogen-activated protein kinase (MAPK) family has been shown to participate in neuropathic pain and axonal regeneration after nerve injury. However, its role in axotomy-induced neuronal apoptosis remains unclear. This study was aimed to examine p38 phosphorylation in the dorsal root ganglia (DRG) and its role in DRG neuronal loss after axotomy. METHODS: Left sciatic nerve transection was performed in all rats. For the temporal study of p38 phosphorylation, the rats were sacrificed at 1 day, 2 weeks, and 2 months after injury. In the second experiment, the rats were divided into control and inhibitor groups receiving vehicle and p38 inhibitor (SB203580, 200 µg/kg/day intraperitoneally once daily), respectively, for 2 weeks. RESULTS: The p38 phosphorylation was increased in L4/5 DRG at 2 weeks after transection. Immunoreactivity of phospho-p38 was mainly observed in the cytoplasm of small neurons with additional nuclear localization in the axotomized neurons at 2 weeks. SB203580 could reduce the phosphorylation of p38 and its substrate, ATF2, including the upregulation of total caspase-3 expression in the DRG. Moreover, count of L4/5 DRG neurons revealed significantly decreased cell loss in the inhibitor than control groups (17·4% versus 32·5%). CONCLUSION: These data suggest the role of p38 in sensory neuronal loss after nerve transection. Future studies should be done to confirm the apoptotic role of p38 in this condition.

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BACKGROUND: Cisplatin is used as an anti-neoplastic agent against several cancers. Neuropathy is one of its major side effects that contributes to patients' intolerance to the standard regimen. Sex-related differences have been reported in nerve injury and neuropathies. However, there has been no study on cisplatin regarding this issue. OBJECTIVE: Compare various abnormalities in cisplatin neuropathy between sexes. MATERIAL AND METHOD: Two mg/kg of cisplatin was administered intraperitoneally twice a week for five consecutive weeks. Body weight, heat latency of hind paw and sciatic motor nerve conduction velocity (MNCV), pathological alterations in the sciatic nerve and dorsal root ganglion (DRG) including the level of NGF in the sciatic nerve were examined. Untreated rats of both sexes were used as controls. RESULTS: Weight loss, prolonged heat latency, and slow MNCV in the treated rats of both sexes with higher severity in males were showed. Furthermore, reduction in myelinated fiber diameter, myelin thickness, and myelinated fiber density was more severe in females, whereas, atrophy of neuronal cell body, nucleus, and nucleolus was more striking in males. The decreased level of NGF was similar between sexes. CONCLUSION: These data suggest the differences in various aspects of cisplatin neurotoxicity between sexes. However, future studies are needed to verify this issue in a clinical condition and clarify the underlying mechanisms.

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BACKGROUND: Paclitaxel, an anti-neoplastic agent effective against several solid tumors, has several side effects including peripheral neuropathy. So far, there are no effective treatments for this complication. Monosialic acid ganglioside (GM1) has been shown to protect neurons against injuries and degeneration. However, its efficacy in the treatment of paclitaxel-induced neuropathy has not been verified. OBJECTIVE: To evaluate the effect of porcine GM1 on neurophysiological abnormalities in rats receiving paclitaxel. MATERIAL AND METHOD: Fifty-four Wistar rats were divided into control, vehicle for paclitaxel (Cremophor EL), paclitaxel, and paclitaxel + GM1 groups. Paclitaxel 16 mg/kg/week for five consecutive weeks was given intraperitoneally. Treatment with 30 mg/kg 5 days per week of GM1 was started 3 days prior to the first dose and continued until 3 days after the last dose of paclitaxel. Tail and hind paw thermal thresholds including tail motor nerve conduction velocity (MNCV) were measured prior to and after the start of treatments. Histopathology of the sciatic nerve was also examined. RESULTS: Paclitaxel alone induced thermal hypoalgesia and reduced tail MNCV Less severe abnormalities were also found with the vehicle. GM1 appeared to prevent the development of hypoalgesia and ameliorated the decreased MNCV without any evidence of Guillain-Barre Syndrome. Mild endoneurial edema and axonal degeneration in the sciatic nerve sections were seen in paclitaxel treated rats. Microtubule accumulation and activated Schwann cell were also presented in the paclitaxel treated groups. CONCLUSION: These data suggest that porcine GM1 may be useful in the prevention and treatment of paclitaxel-induced neuropathy. However the adverse effect of Cremophor EL should be of concern.

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Morphometric analysis of nerve biopsy provides data of structural changes that are essential for early detection of peripheral neuropathy. Because of the laborious work associated with the total fiber quantification, various sampling methods have been introduced with controversial accuracy. Three-window sampling technique has been recently proposed to provide the accurate morphometric data of normal human sural nerve. However, its application in the diseased nerve has not been validated. This study, therefore, compared the morphometric data of nerve biopsies from 12 patients with various neuropathies obtained using this sampling method and those obtained by total fiber analysis. Total number, density, and diameter of myelinated fibers including myelin thickness and g ratio were analyzed. Intraclass correlation coefficients ranging from 0.95 to 0.99 indicate the high agreement between the data derived from the two methods in these parameters. This finding suggests the accuracy of the three-window sampling technique in the morphometric study of nerve with pathological alterations.

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