The longitudinal arrangement of collagen bundles and the impressive amount of elastic and elaunin fibers should elicit considerable elastic properties to the FT. An altered elasticity mechanism has been proposed for TCS; further studies are needed with TCS patients to define whether the collagen structure, Type 1/Type 3 proportion, or elastic fiber content are altered, which could lead to new histopathological definitions of TCS, helping neurosurgeons in the difficult management of TCS patients with normal level conus medullaris.

Intracranial hypertension (IH) develops in approximately 50% of all patients with severe traumatic brain injury (TBI) and is more common in patients with intracranial hematoma (ICH) 1,2 . Therefore, it is very important to identify a suitable animal model to study and understand the pathophysiology of refractory IH to develop effective treatments.Many models of neurosurgical experiments in small animals, such as rats and cats, have been developed; however, compared to humans, they have smaller brain volumes and more distinct behaviors 3,4 . While there are existing porcine models, they simulate ICH by infusing autologous blood into the brain tissue and do not replicate intracranial lesions [3][4][5][6] . ABSTRACTObjective: Intracranial hypertension (IH) develops in approximately 50% of all patients with severe traumatic brain injury (TBI). Therefore, it is very important to identify a suitable animal model to study and understand the pathophysiology of refractory IH to develop effective treatments. Methods: We describe a new experimental porcine model designed to simulate expansive brain hematoma causing IH. Under anesthesia, IH was simulated with a balloon insufflation. The IH variables were measured with intracranial pressure (ICP) parenchymal monitoring, epidural, cerebral oximetry, and transcranial Doppler (TCD). Results: None of the animals died during the experiment. The ICP epidural showed a slower rise compared with parenchymal ICP. We found a correlation between ICP and cerebral oximetry. Conclusion: The model described here seems useful to understand some of the pathophysiological characteristics of acute IH. Keywords: experimental model, intracranial hypertension, transcranial doppler sonography. RESUMOObjetivo: A hipertensão intracraniana (HIC) ocorre em até 50% de todos os pacientes com traumatismo cranioencefálico (TCE). Por isso, é importante estabelecer um modelo animal adequado para estudar a fisiopatologia da HIC refratária, com a perspectiva de desenvolver tratamentos eficazes. Métodos: Os animais foram submetidos a um protocolo padrão de anestesia. A hipertensão intracraniana foi estabelecida através de insuflação de um balão. As variáveis HIC foram medidas com a pressão intracraniana (PIC) do parênquima, oximetria, epidural e doppler transcraniano. Resultados: A PIC epidural apresentou elevação mais lenta, comparada com a PIC parenquimal. Houve correlação entre a PIC e a oximetria cerebral. O registro da PIC, oximetria e índice de pulsatilidade foi realizado em todos os animais sem dificuldade. Conclusão: O modelo descrito parece ser útil para a compreensão de algumas características fisiopatológicas na HIC aguda.Palavras-chave: pressão intracraniana, ultrassonografia, doppler transcraniana, modelos experimentais.

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