Craniotomy around the Occipital Condyle : How to drill the Lateral Part of the Foramen Magnum, Jugular Tubercle, and the Occipital Condyle(SPECIAL ISSUES : Essential Standard Techniques of the Microsurgery)

Abstract

Methods for safe dr111ing in a cralliotomy aI ・ ound the occipital condyle are mentioned and the differences in 亡 he operative view between before and after removal of each borly eiement are discussed ． In the field obtained just after craniotomy ， the latera1 rim of the foramen magnum （ posterior part of the jugular tubercle）obstructs the view toward the anterior part of the posterior fossa ． Drilhng of this area ， carried out by fol1Qwirlg the pQsterlor condylar emissary vein and imaging the sigmoid − magnum triangle ， exposes tke lower cerebellopontine angle and the region ventral to the brainstem ． In order to drill down the high jugular tubercle ， dril ！ ing of part of the occipital condyle is also required to make room to reach the tubercle toward its summit ， as the dura covering the posterior part of the tubercle is hard to elevate 、 Additional drilling of the posterior part of the occipita ！condyle makes a wider space available ， especialIy around the vertebral artery ． Therefore ， a specifically tailored operation should be scheduled for each case ， considering which bony part is to be rernoved ． （