Surgical Aspects of Ventriculography *

I IROIPOSE to deal with the surgical aspects of ventriculography, anid at the beginning I want to emphasize two principles whichi are fundamental first, the necessit-for a clinical diagnosis before ventriculography is attempted; second, the necessity of being prepared to perform at a momenit's notice any intracranial operation after ventriculographyl has been done. Ihe first principle ma) appear paradoxical, for if there be a clinical diagnosis, wh}y do a ventriculography? In the great majority of cases a clinical diagniosis can be macle, and the very absence of "localizing" signs localizes in some degree the lesion in certain regions of the brain. If clinical methods cannot tell us where a tumour is, they can nearly alwxays poinit to some of the places in xhich it is not, and the side and site of the preliminary puncture of the ventricle must be determined by some sort of clinical localization. Moreover, one or both of the lateral ventricles may be (lisplacecl, and the finding of them may depend on clinical rather tlhain anatomical clata. WNhen ventriculography is indicated, the ventricles are probably not normal. Again, it is wrong to pass a needle into a vascular tumour, and the clinical history apart from the clinical signs may give some indlicationi of the nature of the growtth. TIo perform ventriculography before, for instance, examining, the visual fields in cases where perimetry is practicable, may be a very culpable short cut. Formerly ventriculographv was done if the tumour could not be localized other-xvise. Now it is done, not only for that reason, but also to confirm the clinical diagniosis and to give more precise information about the site and the size of the growth. Otn the interpretation of the ventriculograms depend the size and situation of the operative exposure, andi these may determine the success of the operation. rhe seconid fundamental principle is preparedness-not merely for an emergency deconmpressioni, ventricular puncture, or dehydration, but for formidable procedures like removal of a pineal tumour or of a tumour of the third or fourth ventricle. \Vhen intracraniial pressure is high, there is a sort of balance between the various intracraniial forces. TIhe mere puncture of a ventricle will disturb this balance, and a tumour may slip or swell sufticientlv to exert fatal pressure on some vital area. If a simple puncture will do this, howv much more the introcluction of any foreign gas or fluid. One imiust be …