J Neurol Surg B Skull Base 2015; 76 - P065
DOI: 10.1055/s-0035-1546693

Endoscopic Skull Base Surgery Kinetics: A Novel Approach to Instrument Motion Analysis

Angelique Berens 1, Jed White 2, Richard Harbison 1, Randy A. Bly 1, Kristen S. Moe 1, Manual Ferreira 3, Sharon Newman 4
  • 1Department of Otolaryngology, University of Washington, Washington, United States
  • 2Applied Biomechanics Laboratory, University of Washington, Washington, United States
  • 3Department of Neurosurgery, University of Washington, Washington, United States
  • 4 Department of Bioengineering, University of Washington, Washington, United States

Background: Minimally invasive surgery continues to gain ground across all surgical specialties. The importance of economy of motion for surgeon training, improved patient outcomes, and decreased operative time is discussed in the literature. CT navigation and trackable instrumentation give a potential platform for analyzing surgical motion (Woerdeman et al 2006). Endoscopic skull base surgery could be improved using technology to trace instrument trajectory, velocity, and excursion, recording and analyzing instrument motion to enable creation of a new model for sophisticated computer-aided preoperative planning.

Introduction: The purpose of this study is to develop and test a new model of recording and analyzing instrument motion during endoscopic skull base surgery. With the use of CT navigation tracking systems, surgeons and engineers developed a novel technique for recording the x, y, and z coordinates of trackable instruments relative to the patient's preoperative CT scan during surgical procedures on cadavers. The coordinates can be used to create a point cloud on the patient's preoperative CT scan, so further measurements of velocity and angle of movement are possible. Problems of perceived inaccessibility, inadvertent injury to critical neurovascular structures, and cerebrospinal fluid leaks are addressed to increase safety while decreasing morbidity. With this technology, there exists the possibility of defining standard pathways from an entry portal to the target lesion.

Design: A cadaver head underwent CT scanning, and was registered for surgical navigation. The surgical approach was recorded with navigation software (iNtellect Navigation software, Stryker Corporation, Kalamazoo, Michigan, United States), modified to record instrument position and rotation information at 8 Hz for the duration of the operative procedure. This software runs in the background without change to the surgeon's user interface.

Following data collection, image segmentation software (SegView, Seattle, Washington, United States) was used to create a 3D surface model of the cadaver head and the instrument tip coordinates were overlaid onto the model as a point cloud in a computer-aided design tool (Form-Z, AutoDesSys, Columbus, Ohio, United States).

Results: A method and software were developed to enable depiction and analysis of instrument motion in a point cloud distribution. The model functioned in documenting the location and velocity of endoscopic instrument motion. With this, the actual volume of the surgical pathway could be studied and standard pathways could be defined.

Discussion: Kinetic analysis of surgical instrument motion is an underdeveloped field. The techniques developed in the study will allow further optimization of endoscopic skull base procedures. This model is expected to define precisely the surgical pathway between the entry portal and target pathology for a variety of skull base approaches. This data will also be highly applicable in defining geometric requirements for the development of future portals and pathways for these complex surgical procedures.