A NEW METHOD FOR EXTRACTION OF CRANIAL FOREIGN-BODIES

Identification and extraction of penetrating cranial foreign bodies ca n cause problems in some cases. Small fragments localized deep in the orbit or cerebrum can be especially hard to detect. Severe bleeding an d traumatized anatomy can make orientation difficult. We used a new lo calizing device, computer-assisted surgery (CAS), to good effect in si x such cases. CAS is a localizing technique designed to assist the hea d surgeon during surgery, providing real-time position information. Th e method is based upon a three-dimensional volume model of the patient 's skull generated by preceding computed tomography imaging procedures (CT or MRI). Intraoperative correlation of a 3D-model and the patient 's skull allows for real-time position display of a surgical instrumen t on the monitor screen. Thereby the surgeon is able to localize even small foreign bodies without extensive exploration. In the case of mul tiple foreign bodies the surgeon calls up a simple documentation facil ity recording which of the visible fragments have already been extract ed. We successfully used the system for extraction of orbital foreign bodies in four and intracerebral foreign bodies in two cases. In a 4-y ear-old child with gunshot injury the bullet was located in the precen tral region and was easily extracted with the CAS system. In a 21-year -old man 39 glass fragments were extracted from the left orbit. In a 3 6-year-old man a bone fragment was dislocated to the apex of the orbit directly under the optic nerve. Location and extraction were achieved without damage to the orbital structures with the help of the CAS sys tem.