Tumoral lesions of the spine can represent great challenges for a surgical team. Many techniques have been proposed for surgical training as a learning process for young surgeons or for the simulation of complex procedures. A rapid prototyping technique has been presented recently as an option for these purposes 1 . Among prototyping forms the stereolithography, a technique developed in 1987 for aerospace industry stands out. It is based on models and graphic computation of images and create solid molds in resins, ceramic or metals 1,2 . As of the end of the 90's the first adaptations were accomplished for application in the biomedical area, substituting the drawings of graphic computation with images of a medical scanner such as computerized tomography (CT) and magnetic resonance image (MRI), whereby physical models of the human anatomy are built 3 . Several techniques of rapid prototyping have been developed, and all are based on the construction of anatomical representations in a threedimensional structure, elaborated layer by layer 1,4 . The technology is based on the photopolimeryzing of a resin through an ultra violet laser. A controller positions a vertical elevator, initially on a container full of photosensitive resin, so that just a fine liquid layer is on the platform 1,5 . When the laser reaches the surface of the resin, this is solidified and the first layer of the model is built. After this, the elevator goes down submerging the layer recently solidified. The process of scanning laser is repeated and a second layer is elaborated on top of the first. The process of scanning laser is repeated so that the whole model is built. The purpose of this work is to demonstrate the practical use of the stereolithography an auxiliary method for training and surgical simulation 1 . AbSTRACT -Many techniques have been proposed for surgical training as a learning process for young surgeons or for the simulation of complex procedures. Stereolithograpfy, a rapid prototyping technique, has been presented recently as an option for these purposes. We describe the case of a 12 years old boy, diagnosed with Ewing´s sarcoma in the cervical spine. After a surgical simulation accomplished in the prototype, built by stereolithography, the patient was submitted to a C4 corpectomy and to a C4 and C3 laminectomy with anterior and posterior fixation, a non intercurrence procedure. This technique is an innovative and complementary tool in diagnosis and therapy. As a result, it is easier for the surgeon to understand the complexity of the case and plan the approach before any surgical procedure. APLICATION OF THE STErEOLITHOgrAPHy TECHNIQUE IN COMPLEX SPINE SUrgEryKEy WoRdS: spine surgery, rapid prototyping, stereolithography. Aplicação da técnica de estereolitografia em cirurgias complexas da colunaRESUMo -Lesões tumorais da coluna podem representar um grande desafio para equipe cirúrgica. A estereolitografia é uma técnica de construção de peças anatômicas a partir de desenhos gráficos ou exames radiológicos. Apresentamos um paci...

Sodium disorders are the most common and most poorly understood electrolyte disorders in neurological patients. The aim of this study was to determine the incidence of sodium disorders and its association with different traumatic brain injuries. This prospective study was conducted in 80 patients diagnosed with moderate and severe traumatic brain injuries. All patients underwent cerebral computed tomography. Incidence of sodium disorders, presence of injuries in the first computed tomography after traumatic brain injury, and level of consciousness were analyzed. Patients that presented other potential causes of sodium disorders and systemic trauma were excluded from the study. The incidence of sodium disturbances was 45%: 20 patients presented hypernatremia and 16 hyponatremia. Refers to all patients with sodium disturbances 53% were detected in the first sample. We recorded at least one measurement <125 mEq/L in 50% of the patients with hyponatremia. A greater incidence of sodium disorders was found in patients with subdural, intracerebral hematoma and with diffuse axonal injury. The incidence of sodium disorders among the patients with diffuse lesions was greater than in the group of patients with brain contusion (P = 0.022). The incidence of sodium disorders is higher in patients with diffuse traumatic brain injuries. No association was found between focal lesions and proportion of sodium disorders.