Relationship between function recovery and the changes of mitochondria after facial muscles denervation

doi:10.3321/j.issn:1673-8225.2003.23.014

Abstract：AIM:To explore the relationship between the functional recovery of facial muscles and the changes of the structure of mitochondria and succinate dehydrogenase (SDH) of oris muscles after different degree of denervation. METHODS:Models of facial paralysis were obtained, all 72 guinea pigs were divided into 5 s-pinching group,15 s-pinching group and 30 s-pinching group respectively.Eletroneurogram (ENoG) was used to measure the average threshold differences of the facial nerves of the guinea pigs in each group.The mitochondria structures of oris muscle and positive products of SDH were observed with transmitting electron microscope after facial nerve injuries for 15,30 s respectively. RESULTS:The longer of pinching, the more of threshold difference, 5 s-pinching group (11),15 s-pinching group (10),30 s-pinching group (10). Difference of threshold values of each group was 0.443± 0.024, 12.174± 1.532, 15.720± 1.536, there was a significant difference between groups (F=461.560, P< 0.000 1).The average inhibitory time of nerve excitement conduction was (35± 17) min after pinching the facial nerve for 5 s. Recovery of blink reflex took the guinea pigs in 15 s-pinching group an average of(47± 15) days,and it failed to occur within 6 months in the 30 s group.Electron microscopic studies revealed broken mitochondria crista and decreased positive reaction granules of SDH in guinea pigs of 15 s-pinching group after 15 days,which recovered basically after 30 days.Bubble degeneration and decreased SDH granules could be found in guinea pigs of 30 s-pinching group after 15 days, and were slightly recovered 30 days later. CONCLUSION:The longer time the facial nerve is injured and the more serious the degree of denervation was sustained, the changes of the mitochondria including that of SDH would be more serious and more difficult to recover, so the facial nerve injury should be managed as early as possible.