Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4532_Библиотеки_им_академика_М_И_Перельмана

While the pathogenesis of traumatic fi stulas is intuitive, spontaneous leaks recognize a multifacto­rial origin: intracranial pressure, brain pulsation, cranial base pneumatization, and arachnoid pits (the so-called four P’s of fi stula formation) are thought to play a major role. The presence of elevated intra­cranial pressure may cause a gradual distension of the meningeal sac and the formation of a cephalo­cele through congenital defects of the skull base or a natural avenue of least resistance such as the sel­lar diaphragm. Eventually, the meninges break down and CSF leak occurs. The fi stula can be considered as a pressure relief valve, and the leakage is very diffi cult to be controlled until intracranial pressure is restored to normal values. Brain pulsation may be responsible for thinning and erosion of the bone of the skull base and the development of a cephalocele through a con­genital or traumatic defect. In hyperpneumatized pa­ranasal sinuses and temporal bones the skull base is very thin and may have different paths of least resis­tance for the development of a fi stula. The presence of arachnoid villi in communication with basal men­ingeal veins along the skull base cause the “pitting”