A new method of localize the choroid point of the PICA and the venous copular point on the lateral projection of vertebral angiography.

The location of the choroid arterial point as well as of the copular venous point with reference to a line, dealing with the anatomical structure at the level of the cervicooccipital joint, was found to be a quick and accurate method for the diagnosis of tonsillar herniation. The application of this method has the advantage of giving the location of the choroid arterial point, and a control of the venous time of arteriography by the location of the copular point.