Surgical anatomy and surgical approaches of the third ventricle

Careful analysis of MRI images is mandatory before any surgical procedure i n the third ventricle This analysis should take in account the relationship of the tumor itself but also thr grade of hydrocephalus and the,main anato mical landmarks along the surgical approach. The first step is the access t o the lateral ventricle, which may be achieved via transcortical or anterio r transcallosal routes: these two operative procedures are detailed. The tr ansforaminal entry to the third ventricle may be easy if hydrocephalus has widened the foramen of Monro. In other cases, a subchoroidal (or interthala mo-trigonal) approach is necessary, and the division of the thalamostriate vein is sometimes required. In this series, the transcortical route has bee n favoured by neurosurgeons. The advantages and drawbacks of both transcort ical and anterior transcallosal routes are discussed. fie anterior interhem ispheric and pterional approaches are briefly evoked as they were used in v ery few eases of this series. The management of hydrocephalus is discussed.