Accessibility and Resectability of Craniopharyngiomas

Abstract

Background: The degree of adherence of craniopharyngiomas to surrounding structures can not be fully assessed by means of preoperative neuroradiological examination. Reasonable extent of the radicality of tumor removal may be established only after its sufficient exposure during the operation. Aim and Methods: The results of morphological studies of 30 sectional cases of craniopharyngiomas of different topographical groups and the results of magnetic resonance imaging and operative findings in 102 consecutive patients operated during the years 1991 to 2006 were analyzed in order to find the principles of the choice of the most convenient surgical approach to craniopharyngiomas. Results: The trans-sphenoidal approach to primarily infradiaphragmatic (that is, intrasellar or intrasellar and suprasellar) craniopharyngiomas allows identification of the remnants of the pituitary at the bottom of a large and deep sella more readily than does craniotomy. The transcranial approach is necessary in intrasellar and suprasellar tumors of dumbbell shape, with parasellar growth, or of considerable size and relatively small sella. Partial prechiasmatic extension of the great majority of extraventricular suprasellar craniopharyngiomas allows tumor removal between the optic nerves, through the opticocarotid triangle, or laterally to the carotid via subfrontal or pterional approach. Removal of the extraventricular tumor through the lamina terminalis or the foramina of Monro may jeopardize hypothalamic structures of the floor of the third ventricle located on the upper surface of the tumor. The most common location of supradiaphragmatic craniopharyngiomas is partially inside and partially outside the cavity of the third ventricle. These intraventricular and extraventricular craniopharyngiomas are located behind the optic chiasm. Opening of the lamina terminalis allows good exposure and removal of the majority of these tumors as well as of rare purely intraventricular craniopharyngiomas. However, direct visualization of the superior part of a large or giant tumor reaching the roof of the third ventricle can be reached only after extending the exposure above the anterior communicating artery or by using a transcallosal or transfrontal approach. According to our experience, a suitable approach to giant intraventricular and extraventricular craniopharyngiomas is combined: one-stage subfrontal and transcallosal approach through one large unilateral frontal craniotomy. Conclusions: There is no universal surgical approach to either intrasellar and suprasellar or to suprasellar craniopharyngiomas. The relationships of the tumor with the surrounding structures (sella and the pituitary, optic chiasm, floor of the third ventricle) are variable and at the same time characteristic for different topographical groups of craniopharyngiomas which necessitate the choice of an appropriate surgical approach.