[Fractionated stereotactic irradiation of skull-base related tumours].

Abstract

The prognosis of the treatment of brain tumours depends on two main factors: biological nature and localisation of the neoplasm. Requirements of oncologic surgery can be met only partially if at all in neurological surgery of brain tumours. Resectability depends primarily on localisation of the neoplasms. The leading principle is preservation of fine neural structures, minimising morbidity from tissue resection with the goal of maximal tumour resection. As nervous structures and the target volume do not move in the intracranial space, large radiation doses unusual in traditional radiotherapy can be given either in one or in fractionated sessions to small targets (point-radiation) and a well-controlled radiation necrosis of the pathological tissue can be achieved. Management principles of treatment of skull-base related tumours are very similar due to high risks of functional morbidity evoked by surgical injury to the cranial nerves, brainstem structures, vessels of the Willis circle and those of the substantia perforata anterior and posterior, etc. Such tumours are neoplasms arising from the skull base, those infiltrating the cavernous sinuses, invasive pituitary tumours, those arising from the glomus jugulare, or located within the cerebello-pontine angle, etc. This manuscript intends to illustrate and prove the hypothesis by means of 4 cases that fractionated stereotactic radiotherapy (fSRT) is an important part of treatment armamentarium in the latter cases, as it is capable of exploiting both the advantages of traditional fractionated irradiation and that of the high conformality and selectivity of radiosurgery. It is capable of administering appropriate quantity of total target dose with a lower than limit dose on surrounding structures. The presentation proves that fSRT can be planned already in the phase of surgical indication as a "microsurgery-assisted radiotherapy".