The Experimental Study Of Blast Injury Of Facial Nerve

Department of Oral and Maxillofacial surgery, Stomatological College, Fourth Military Medical University, Xi 'an, ChinaBetween 1945-1987, there were 214 local wars, with 100 million casualties and 25 million deaths. Since then, contrary to expectation, local wars have increased dramatically. With the increase in the efficacy of sophisticated weaponry, so the number of victims has increased, and local wars should claim more attention from the medical professions.Blast is one of the main causes of injuries or death in this era and is neglected or not fully described in the medical literature. Blast injuries cause a specific form of blunt trauma with a high mortality rate and many serious multiple injuries in general and specifically in the maxillaofacial region. In a war zone, the face more than other part of the body, remains uncovered and exposed to injury. The architectural?conception and anatomical variation of the essential skeletal construction of the middle- and lower-third of the face lead to different types of injury when exposed to a shock wave. So the studies on maxillofacial blast injury are not only important but also very necessary for medical practice. But now most investigation focus on the facial trauma caused by high-velocity missiles. In the few studies of maxillofacial blast injury, researchers used paper detonator as exploder. But it is difficult to confirm the explosive parameter and to forecast the explosive energy. So it is necessary to build a standard animal model for maxillofacial blast injury. Facial nerve is an important anatomic apparatus which has very important functions. But now the studies on facial nerve blast injury still have not published in medicalliterature. As the spontaneous recovery of traumatic facial paralysis is difficult, to thoroughly study the cytologic basis and the molecular mechanism on the pathology changes and recovery of traumatic facial nerve has been the key to recognize and solve the problem of facial nerve regeneration. Being a multifunctional polypeptide, TGF- P diffusely participate in the inflammatory reaction, immune regulation, signal transmission, and so on, and plays a significant role in nerve regeneration.Our study firstly established a standard animal model for maxillofacial blast injury by a new dynamite ball. We observed animals' maxillofacial injury after explosive and took skin, muscle and facial nerve at various time point in order to study the characters of blast injury. The nerve specimen was examined in detail under light microscope and electron microscope to confirm the changes of neuraxon, myelin, Schwann cell and fiber tissues after injury. We counted Schwann cell number and observed the expression of TGF- 0 in facial nerve at various time point in the histoimmunochemistrical way to investigate the relationship of Schwann cell and TGF- ?as well as the effect of TGF- P to nerve regeneration.The result indicated that: Exploding this dynamite ball 2mm away from rabbit's left face can lead to facial soft tissue injury and mandibular fracture while the animals still alive. These injuries can be repeated completely. Facial nerve paralysis occurred after exploding. We can observe facial nerve edema, hyperaemia, degeneration and swelling of Schwann's cell and infiltration of inflammatory cells. The major pathology in the wounds of facial nerves is severe indirect injury in nerve trunks. One day later, the facial nerve was found to be broken widely, but the neurilemma is still continuous. There were lots of inflammatory cells in the area of nerve injury. After 3 days, nerve fibers swelled and broke off. One week later, the inflammation began to scatter. The TGF- 3 antibody was positive 3 days later, and reached the tip after 7 days while Schwann cells increased greatly. And then the TGF- P expression decreased gradually. TGF- 3 mainly express hi myelin and correlate to the proliferation of Schwann cells and nerve injury changes.