Rats’ Ischiatic Nerve Injury Caused by Smashing: a Vascularization Study Célia Aparecida Stellutti Pachioni1, Nilton Mazzer2, Cláudio Henrique Barbieri3, Valéria Paula Sassoli Fazan4, Carlos Roberto Padovani5, Carlos Alberto Moro6, Carlos Alberto Aguiar

203 Received in: 03/29/06; approved in: 05/24/06 INTRODUCTION Peripheral nerves injuries show both sensorial and motor functional changes, and, if not appropriately treated, they can yield an important deficit, debilitating not only patients’ quality of life, but also state systems in those cases of early retirement as a result of functional disability (1). Peripheral nerve has a well developed microvascular system at the epineurium, perineurium and endoneurium. Its vessels are distributed along many nerve’s layers, and they are interconnected through numerous anastomoses (2). Nervous impulse transmission, as well as axonal transport, requires a continuous power supply provided by intraneural microvessels. Microvascular system has a large reserve capacity to offset local regional vessels’ motion or injury. At the epineurium, vessels longitudinally oriented exhibit a characteristic pattern, that is, vessels are present in all epineurium layers, which is superficially, as well, between fascicular bundles no nerve’s deep layers (3,4). The importance of peripheral nerves vascularization is due to the fact that peripheral nerves’ axons are vulnerable to ischemia because of the long distance existing between neuronal body and axon length (5). Several studies have proposed the use of experimental models for nervous injury by smashing in order to evaluate both injury itself and functional regeneration and recovery (6,7,8), but the vascular response in an acute peripheral nervous injury by smashing remains poorly known. Experimental peripheral nervous injuries at the ischiatic nerve may be provoked through a number of procedures, such as: smashing by compression, trans-section, stretching and freezing. Several factors such as magnitude, duration and mechanism of compressive trauma are important to determine injury degree (9). When a nerve is submitted to external pressure, an injury can result both from pressure and from ischemia. Ischemia happens when the smashing pressure exceeds capillary perfusion pressure (3,10). Therefore, the study of vascular changes in nervous injuries, particularly those caused by smashing, deserves investigation, since it could contribute to the improvement of treatment strategies for peripheral nervous injury.