Utility of frameless stereotaxy in the resection of skull base and basal cerebral lesions in children

Since 1991, we have performed nearly 300 Stereotactic procedures using the ISG viewing wand on a variety of cranial lesions in patients under 22 years of age. Of these, 38 procedures were performed on 34 patients for basal ce rebral and skull base lesions. Our patients ranged in age from 3.5 months t o 22 years with a mean age of 9.45 years. There were 18 females and 16 male s. Twenty-one patients had basal cerebral lesions located in the thalamus ( 10), basal ganglia (2), third ventricle (2), and hypothalamus (7). Thirteen patients had skull base lesions located within the anterior optic apparatu s (3), sella turcica (4), middle and posterior cranial fossae (4), and cran iocervical region (2). Preoperative CT and/or MRI scan images were taken as a volume acquisition and transferred to the computer workstation utilizing the ISG Wand software. This workstation was transferred-to the operating r oom where it was calibrated to a fare Surgicom arm which interfaces with th e patient and the three-dimensional radiological image. The ISG Wand was ut ilized to plan the scalp and bone flaps and to select the optional trajecto ry to lesion. The surgical approaches which were specifically used in this series with the ISG Wand included transcallosal (15), pterional (5), fronta l (3), subtemporal (4), transsphenoidal (3), temporal (3), tumor cyst shunt insertion (1), burr hole drainage (1), transoral (2), bifrontal (1)1 bifro ntal mid facial (1), and transnasal (1). Although brain shift occurred foll owing craniotomy and with brain retraction, the relative immobility of thes e lesions at the skull or cerebral base permitted an accurate targeting of all lesions with an error range of 1.0-2.5 mm throughout the entire procedu re. This relatively precise intraoperative feedback led to more accurate re cognition of tumor landmarks. It is the authors' impression that a more agg ressive resection of these lesions was achieved than could be without the d evice. We conclude that a frameless stereotactic device such as the ISG Wan d is particularly valuable in the approach to skull base and basal cerebral tumors in children.