Multiple Brain Tumor Nodule Resections under Direct Visualization of a Neuronavigated Endoscope

BACKGROUND: With neuronavigation-assistance, endoscopic neurosurgery has a variety of advantages for brain tumor resection. However, intraoperative neuronavigation has to be operated by frequently alternating a neuronavigation wand and moving the microscope back-and-forth on the surgical field while the microscope is being used for surgery, except when using stereo overlays in the operating microscope aligned to the operative scene. In our practice, our surgical endoscope was used as a sole optical device and was also calibrated as a virtual wand targeting to tumor nodules while the operation was being performed under its simultaneous visualization. This paper gives a brief description and technical report of applications of image-guided endoscopy in two cases with multiple tumor nodules. METHODS: A 0-degree, 4-mm rigid endoscopes (DCI; Storz and Co., Tuttlingen, Germany) and Voyager SX navigation system by Z-KAT (Marconi, USA) were used for both cases, a 32-year-old woman with multiple hemangioblastomas and a 46-year-old man with two recurrent astrocytomas. The endoscope has a digital video output, which was registered with reference calibration for rendered image-guided stereoscopic views. The neuronavigation screen was formatted to provide axial, coronal, and sagittal magnetic resonance (MR) images demonstrating the location and trajectory of the endoscope's tip. Endoscope angles of 0 degrees and 30 degrees were used interchangeably during surgery. For both posterior fossa tumors, an entry point on the skull was identified using "virtual endoscopy" to visualize the intracranial anatomy and lesions. RESULTS: A 3-cm linear skin incision for both cases was made at the entry point guided by the endoscope's video output and a 3-dimensional (3-D) rendered image on the navigation system. Three tumor nodules in the first patient, and two nodules in the second, were removed directly under navigated-endoscopic visualization on one monitor with 3D imaging-guidance images on the other side-by-side. CONCLUSION: The neuronavigated endoscope coordinates of the tip of endoscope, and the trajectory of targets, provide both 3D orientation and direct endoscopic visualization simultaneously, and present with the unique feature for solely endoscopic minimally invasive procedures, especially for multiple intracranial lesions.