From Rigid to Soft Robotic Approaches for Minimally Invasive Neurosurgery

TL;DR

The paper addresses the challenge of enabling minimally invasive neurosurgery within deep brain ventricles by reviewing rigid, soft, and hybrid robotic approaches for flexible endoscopy. It maps explicit surgical requirements for lateral and third ventricle access and evaluates how each robotic paradigm meets these constraints, highlighting safety, interfaces, and evaluation as central hurdles. The authors identify that rigid systems currently lead in capability and reliability, while hybrid continuum robots offer the most promising path toward safe, autonomous follow-the-leader navigation with high curvature and small form factors; soft robots provide safety insights but struggle with precise navigation and scale. The work lays a framework for design choices and regulatory-ready pathways, anticipating meaningful clinical translation in the $5$--$10$ year horizon through improved materials, actuation, and phantoms for robust evaluation.

Abstract

Robotic assistance has significantly improved the outcomes of open microsurgery and rigid endoscopic surgery, however is yet to make an impact in flexible endoscopic neurosurgery. Some of the most common intracranial procedures for treatment of hydrocephalus and tumors stand to benefit from increased dexterity and reduced invasiveness offered by robotic systems that can navigate in the deep ventricular system of the brain. We review a spectrum of flexible robotic devices, from the traditional highly actuated approach, to more novel and bio-inspired mechanisms for safe navigation. For each technology, we identify the operating principle and are able to evaluate the potential for minimally invasive surgical applications. Overall, rigid-type continuum robots have seen the most development, however, approaches combining rigid and soft robotic principles into innovative devices, are ideally situated to address safety and complexity limitations after future design evolution. We also observe a number of related challenges in the field, from surgeon-robot interfaces to robot evaluation procedures. Fundamentally, the challenges revolve around a guarantee of safety in robotic devices with the prerequisites to assist and improve upon surgical tasks. With innovative designs, materials and evaluation techniques emerging, we see potential impacts in the next 5--10 years.

Figures (10)

• Figure 1: Types of neurosurgeries practiced today and their origin.
• Figure 2: The ventricle system and surgical targets for different interventions. (A) Multi-port entry to access lateral ventricles and third ventricle. (B) Single-port entry with a flexible endoscope.
• Figure 3: Requirements for effective minimally invasive neurosurgery. Safety: physical contact pressure and friction should be avoided except at the surgical target; the device should be bio-compatible and minimise risk of infection. Usability: follow-the-leader should be automatic, control should be intuitive for the surgeon; the device must meet the task requirements in terms of curvature, degrees of freedom, scale and end-effector capacity.
• Figure 4: Rigid robots emphasise precise position control and predictability from rigid mechanisms.
• Figure 5: Rigid surgical robot examples (from Table \ref{['tab:my-table']}) (A)--(F): NeoGuide striegel2011determining, Tristable calme2022towards, ETV-ETB gao2019continuum, SMA mandolino2022design, Memoslide henselmans2017memo, Memobox culmone2022memobox.