Neuroendoscopy is a form of minimally invasive brain surgery that uses millimeter sized instruments and long, thin cameras to safely access deep brain structures. These procedures significantly reduce morbidity and blood-loss as surgeons operate though small, centimeter sized, incisions. However, the design of present instruments limit the scope of diseases that can safely be treated using these techniques. Specifically, present hand-held tools lack dexterity at their tip, which prevents surgeons performing the same range of maneuvers that are used in classic, open microsurgery.

This manuscript describes the development of hand-held wristed tube-shaft instruments designed to expand the dexterity of current neuroendoscopic tools. The specific tools described herein are designed to allow surgeons to perform a combined endoscopic third ventriculostomy (ETV) and endoscopic tumor biopsy (ETB) procedure from a single incision. This procedure requires surgeons to access two distinct targets located near the center of the brain, and completing this maneuver from a single opening in the skull is very challenging. Here, an analysis of this clinical problem has been simulated using three dimensional models generated from magnetic resonances (MR) images of patients from the Hospital for Sick Children. This analysis generates important design specifications for the development of dexterous neuroendoscopic instruments.

Following the work-space analysis, an investigation of the design and optimization of a tube-shaft joint mechanism is described, considering surgical task and work-space requirements specific to neurosurgery. This study has led to the development of a novel contact-aided compliant joint mechanism that addresses a significant design challenge encountered in neuroendoscopic tissue manipulation. Namely, the trade-off in joint stiffness and range-of-motion when developing tube-shaft compliant joints at the millimeter scale. Here, we present a novel notch design with an accompanying kinematics and statics model. These models are verified using experimental results of physical prototypes in addition to finite element models for the mechanism.

The joint design is incorporated into a hand-held neuroendoscopic instrument and the reach and function of the instrument is compared to the original simulation based design specifications. This work concludes with preliminary testing of the instrument using phantom models, and a description of the potential applications and future directions of the project.