Neuronavigation. Computer-assisted neurosurgery

The use of stereotactic methods for the resection of subcortical lesions is heavily advoacted in clinical neurosurgery introducing the term "neuronavigation". Though being an unequivacally elegant technique for the localisation and delineation of pathological lesions in the central nervous system neuronavigation has not been validated by any prospective randomized controlled trial. The method is prone to significant errors as to the intraoperative localisation based upon preoperative threedimensional images. The maximum error can be up to 2.6 cm depending on the extent of the so-called brain shift. In comparison classical frame based stereotaxy has a mean error of +/-1 mm and remains the gold standard for the exact threedimensional localisation of a given lesion. The value of neuronavigation is evident for small deep seated vascular lesions. For metastatic tumors or skull base tumors the usefullness is rather marginal because alternative therapies are available with proven and equivalent efficacy and reduced morbidity on one hand, and because of the anatomy of the tumor which makes neuronavigation unnecessary. For the currently most common application of neuronavigation, i.e, surgery of gliomas, no significant improvements of therapeutic results can be expected from neuronavigation. The biology of gliomas limits any mechanical approaches.