Fluid optimization in neurosurgical patients has an important impact on preservation of cerebral perfusion pressure and minimization of cerebral oedema during and after the craniotomy. The investigators would like to know if crystalloids or colloids are equally useful for goal directed therapy in this patients. The investigators will record haemodynamic stability, volume loading and postoperative complications and compare two groups of patients. One group will be optimised with crystalloids and the second with colloids. The investigators will compare also hospital stay and mortality in the two groups.