Stereotactic robot-guided biopsies of brain stem lesions: Experience with 15 cases

Background and purpose Biopsies of brain stem lesions are useful for histopathological analysis, which guide appropriate treatment. The frame-based stereotactic procedure is the gold standard technique for biopsies of the brain stem. For the past few years, a frameless stereotactic robot, the NeuroMate robot (Renishaw, UK) has also been used for brain biopsies. We report a retrospective study of 15 patients who underwent NeuroMate robot-guided biopsies of brain stem lesions to evaluate the efficiency and safety of the system. Methods From January 2004 to March 2006, 15 patients (five children and ten adults) underwent 17 biopsies of brain stem lesions. The lesions were located in the mesencephalon in two cases, in the pons in seven cases, in the pons and the medulla oblongata in five cases, and in the whole midbrain in one case. The biopsy procedure comprised four stages: image acquisition, preoperative planning, patient-to-image registration, and operative procedure. A transcerebellar approach was used in 12 cases and a double oblique anterior frontal approach in five cases. Results Two adults underwent a second procedure because the first biopsy was not contributive. There was no operative mortality. We observed two cases of transient morbidity and one case of permanent morbidity. Conclusions The frameless NeuroMate robot is an efficient and safe instrument for biopsies of brain stem lesions. We believe that the use of frameless stereotactic techniques for brain stem biopsies could increase the number of biopsies and therefore improve the diagnostic yield and accuracy of the technique.