Zamorano-Dujovny multipurpose neurosurgical image-guided localizing unit: experience in 866 consecutive cases of 'open stereotaxis'.

We describe the Zamorano-Dujovny localizing unit which consists of a ring-shaped headholder held on the patient's head by three or four variably placed fixation pins, thereby avoiding interference with the flap sites or craniotomy. The base ring is mounted intraoperatively on a special adapter that allows any patient positioning including supine, lateral prone, 3/4 prone, sitting, etc. Imaging studies, such as computed tomography, magnetic resonance imaging, x-ray, digital angiography, and digital subtraction angiography can be performed with the headholder anchored in place for multimodality image localization. Surgical draping can be done over the ring to provide a completely sterile field. An arc/quadrant localizing device can be mounted on any four alternative positions according to the neurosurgeon's preference. PC-compatible software gives the setting for any possible mounting. Intraoperatively the localizing unit can be used in a 'fixed' permanent setting or as a 'nonfixed' system to provide intraoperative three-dimensional orientation. Different types of instruments compatible with the unit extend its capabilities, such as 'bayonet'-type brain retractors (cylinders and speculum) that keeps the surgical corridor unobstructed from the arc. As an alternative, in the nonfixed setting, self-retaining arms are fixed to the base ring and brain retractors and conventional microsurgical techniques can be used without any mechanical obstruction.