Tibial and fibular nerves evaluation using intraoperative electromyography in rats

Abstract

Intellectual and scientific content of the study. ABSTRACT PURPOSE:To evaluate a new model of intraoperative electromyographic (EMG) assessment of the tibial and fibular nerves, and its respectives motor units in rats. METHODS:Eight Wistar rats underwent intraoperative EMG on both hind limbs at two different moments: week 0 and week 12.Supramaximal electrical stimulation applied on sciatic nerve, and compound muscle action potential recorded on the gastrocnemius muscle (GM) and the extensor digitorum longus muscle (EDLM) through electrodes at specifics points. Motor function assessment was performaced through Walking Track Test. RESULTS:Exposing the muscles and nerves for examination did not alter tibial (p=0.918) or fibular (p=0.877) function between the evaluation moments. Electromyography of the GM, innervated by the tibial nerve, revealed similar amplitude (p=0.069) and latency (p=0.256) at week 0 and at 12 weeks, creating a standard of normality. Meanwhile, electromyography of the EDLM, innervated by the fibular nerve, showed significant differences between the amplitudes (p=0.003) and latencies (p=0.021) at the two different moments of observation. CONCLUSION:Intraoperative electromyography determined and quantified gastrocnemius muscle motor unit integrity, innervated by tibial nerve. Although this study was not useful to, objectively, assess extensor digitorum longus muscle motor unit, innervated by fibular nerve.

Polyethylene glycol fusion associated with antioxidants: A new promise in the treatment of traumatic facial paralysis

“…There is no telling if the electrical stimulus used in the preoperative period was supramaximal or if the intensity was maintained or increased during the experiment, which could cause current leakage and an abnormally high CMAP in response . (3) The stimulating and measuring electrodes were on opposite sides of the surgical field, however, no standardized distance was established between them, which could produce abnormal CMAP results or contamination of electrophysiological answers by branches of the sciatic, sural, tibia, or fibular nerves . (4) The author evaluates CMAP amplitude but not duration or latency, which are also important when considering nerve function.…”

“…The author also reported that distal motor and sensory axon counts were higher in polyethylene glycol‐treated rats. However, in addition to all the problems mentioned in the paragraph above about methodology used for the functional evaluation tests, the authors used female rats that undergo hormonal changes that alters neural regeneration …”

“…9 (3) The stimulating and measuring electrodes were on opposite sides of the surgical field, however, no standardized distance was established between them, which could produce abnormal CMAP 9 results or contamination of electrophysiological answers by branches of the sciatic, sural, tibia, or fibular nerves. 36 (4) The author evaluates CMAP amplitude but not duration or latency, which are also important when considering nerve function. Therefore, although the electrophysiological results obtained by Bittner et al 5 (2012) can be criticized, the behavioral tests demonstrate a significant improvement in neural regeneration in the long term (>60% regeneration in 12 weeks).…”

“…The author also reported that distal motor and sensory axon counts were higher in polyethylene glycoltreated rats. However, in addition to all the problems mentioned in the paragraph above about methodology used for the functional evaluation tests, 9,17,[34][35][36] the authors used female rats that undergo hormonal changes that alters neural regeneration. 42,43 Regarding histologic evaluation, there was no difference found in the total axonal count or in axonal density when comparing groups (Kruskal-Wallis test; P 5 .702; Figure 2; Table 2) as described by Bamba et al 41 Nonetheless, the mean axonal diameter of the groups that used the polyethylene glycol-fusion protocol (groups B and D) was increased (groups A and C; Bonferroni correction test; P .001; Figure 2; Table 2) showing that polyethylene glycol-fusion interfered with demyelination.…”

“…Salomone 40 (2013), using the same animal model with 1 surgical procedure only, describes a mortality rate of 8.3%. Regarding CMAPs, despite most authors claiming that the earlier the better, [34][35][36][37] the absence of statistical differences in the results of all the histologic and functional variables when we compare groups using only microsutures (group A vs group C; control groups), which is, up to today, the gold standard for neurotmesis, 34,37,39,44 in the third and sixth week after nerve severance (Mann-Whitney test; P .488 in both cases) leads us to the conclusion that regarding very severe nerve lesions, surgical intervention in feasible 24 or 72 hours after trauma with no consequences on the final outcome.…”