Operative treatment of lesions in the region of the tentorial notch.

After a description of the topographic anatomy, the different approaches to the tentorial notch and the details of technique are illustrated by a few examples. The pterional approach permits surgical treatment of lesions in the supratentorial region of the anterior and middle third of the tentorial opening. Any approach to the infratentorial region can be enlarged and improved by incising and stitching back the free margin of the tentorium. The medial occipital approach is appropriate for space-occupying lesions situated medially in the ascending portion, that is in the posterior third of the free margin of the tentorium. Infratentorial tumours in the cerebello-pontine angle and in the prepontine region, with extension into the tentorial notch, are best treated through the lateral suboccipital approach. A subfrontal infrachiasmatic procedure is indicated in the case of suprasellar lesions with parasellar extension into the tentorial notch, if the anatomy of the optic chiasm allows it. The location of any particular lesion may call for a combination of different approaches.