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Frameless stereotactic brain biopsy procedures using the Stealth Station: indications, accuracy and results.

This study presents the results of 57 stereotactic brain biopsies using a frameless neuronavigation system, the Stealth Station. The supratentorial lesions had a mean diameter of 33 mm and a mean distance of 32 mm from the entry point at brain surface. In all cases the stereotactic procedure was planned in the preoperative 3-D magnetic resonance data set. In seven cases additional data for identification of eloquent brain areas was integrated from magnetoencephalography or functional magnetic resonance imaging. During surgery the samples were sent to neuropathological examination and the operation completed after the confirmation of pathological tissue. Using this method, in 56 cases a pathological tissue was obtained and a diagnostic yield of 98% was achieved. In two cases (3.5%) a new neurological deficit remained (hemiparesis and visual field deficit). The mean operation time was 92 minutes including examination of frozen sections. The results of our series demonstrate, that frameless stereotactic systems can also be reliably applied for biopsy of supratentorial lesions larger than 15 mm. Frameless stereotaxy in combination with intraoperative pathological confirmation is a safe and reliable method for stereotactic brain biopsy with a diagnostic yield comparable to frame-based stereotaxy.