Image-Guided Endoscopy: Description of Technique and Potential Applications

Marc R. Mayberg, M.D.; Eric Lapresto, M.S.; Edwin J. Cunningham, M.D.

Disclosures

Neurosurg Focus. 2005;19(1) 

In This Article

Abstract and Introduction

Object: Neuroendoscopic approaches to lesions of the central nervous system and spine are limited by the loss of stereoscopic vision and high-fidelity image quality inherent in the operating microscope. Image-guided endoscopy (IGE) and image-guided surgery (IGS) have the potential to overcome these limitations. The goal of this study was to evaluate IGE for its potential applications in neurosurgery.
Methods: To determine the feasibility of IGE, a rigid endoscope was tracked using an IGS system that provided nav-igational data for the endoscope tip and trajectory as well as a computer-generated, three-dimensional, virtual repre-sentation of the image provided by the endoscope.
The IGE procedure was successfully completed in 14 patients (nine with pituitary adenomas, one with a temporal cavernous malformation, and four with unruptured aneurysms). No complications could be attributed to the procedure. Compared with direct microscopy performed using anatomical landmarks, registration of the endoscope, and virtual image were highly accurate.
Conclusions: This procedure offers many potential advantages for central nervous system and spinal endoscopy. Advances in IGE may enable its application to regions outside the central nervous system as well.

Image-guided surgery has been widely applied for neurosurgical,[1,3,24] otolaryngological,[11,14] and other procedures.[8,28] This modality provides highly accurate real-time information to the surgeon regarding localization, trajectory, and depth of instrument end, and frequently enables less-invasive approaches to lesions of the brain, skull base, and spine.

Endoscopy has been applied to various neurosurgical procedures, including the resection of intraventricular,[25,30] sellar and parasellar,[15,18] intraspinal and paraspinal,[4,10] extraaxial intracranial,[2] and vascular lesions.[7,23] Pituitary tumors and other lesions of the anterior skull base and clivus are particularly well suited to transsphenoidal endoscopic surgery because of the ease of access through the nostril, the working space provided by the sphenoid sinus, and fields of view that are potentially wider and nonlinear compared with those offered by direct microscopy.[1] Nevertheless, transsphenoidal endoscopy sacrifices the stereoscopic view provided by direct microscopy, and orientation (especially midline) may be more difficult without exposure of anatomical landmarks. For these reasons, many surgeons prefer a transnasal, extramucosal approach in which direct microscopy is used,[27] because the morbidity related to this approach is comparable to that of endoscopy. Computer-generated virtual reality representations can be combined with real-world views to produce "augmented reality."[22] Currently, augmented reality applications in medicine are being developed for neurosurgery,[17] otolaryngology,[11] orthopedic surgery,[8] maxillofacial surgery, and general surgery.[6,29]

To address the relative loss of stereoscopic depth perception and orientation related to endoscopy, we combined IGS with rigid endoscopy to treat various intracranial and sellar lesions. We hypothesized that accurate localization of the endoscope's tip and trajectory would facilitate orientation and enable less-invasive approaches. In addition, coregistration of a computer-rendered 3D virtual representation of the endoscope's field of view would potentially augment depth perception and display healthy and diseased structures that are not directly visible to the endoscope.

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