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Supplementary Photographic Technique

A disadvantage in using air to outline the ventricular system is that only portions of the ventricular system can be demonstrated at anyone time. In aqueduct stenosis, the length of the affected segment must be determined, as some cases are due merely to a septum (d. Figure). Perforation of such a septum restores normal cerebrospinal fluid circulation (TURNBULL & DRAKE 1966). In the past composite drawings were used to demonstrate the pathology (LYSHOLM et coll. 1935). With the technique of 'addition' this can be accomplished on one film. This is done in the same manner used to photographically combine the encephalogram and angiogram (ROSEN et coll. 1970). Two films are chosen from an encephalography or a ventriculography. These films must be taken in precisely the same projection and with the same degree of magnification. The only difference is the location of air within the ventricles, cisterns or subarachnoid space. The equipment is the same as that used in our technique for subtraction (JENKIN et coll. 1970). This includes: (1) A contact printer using either multibulb or a single high intensity light controlled by a variable voltage rheostat.