Importance of the perforating arteries in the proximal part of the PICA for surgical approaches to the brain stem and fourth ventricle - an anatomical study

Objective

The purpose of this study is to examine the perforating arteries (PAs) in the proximal part of the posterior inferior cerebellar artery (PICA) for surgical approaches to the brain stem and fourth ventricle, and to stress their importance in microsurgical procedures.

Methods

Twenty-six adult cadaver obtained from routine autopsies were used. During the examination, the PAs and the segmental structure of the proximal part of the PICAs and their relation to the neighbouring anatomical structures were demonstrated.

Results

We classified the PICAs into 4 types on the basis of the distance of the middle point of the width of the caudal loop to the midline, and their presence or absence as Group A (symmetrical, anterior medullary type: 26.9%), Group B (lateral medullary type: 15.4%), Group C (asymmetrical type: 38.5%), and Group D (unilateral type: 19.2%). The number of the PAs in the tonsillomedullary segment and the caudal loop was higher than those originating from the other segments.

Conclusions

Approaches to the medial or lateral of the PICA should be made in a way that protects the PAs (avoiding retraction of the PICA). Otherwise the PAs will be damaged and as a result brain stem ischaemia may occur, which can have serious clinical outcomes.