Flexible Sheath for Neuroendoscopic Access
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Solution Overview
Problem
Conventional neurosurgical techniques using rigid sheaths for endoscopic procedures in the brain face limitations such as small instrument access, inability to use multiple instruments simultaneously, and constant pressure on surrounding tissue, which complicates procedures like tumor resection and increases the risk of collateral tissue damage.
Innovation Solution
A flexible sheath system is introduced, comprising a multipart rigid sheath assembly with an obturator for initial insertion, followed by a resilient flexible sheath that accommodates standard surgical instruments and allows for temporary deformation to reduce pressure on brain tissue, enabling multiple instrument use and angled maneuvers without constant displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid operating sheath with fixed small size is used, then the sheath provides structural stability and maintains a passageway, but it exerts constant pressure on surrounding brain tissue and limits instrument access
Solution Approach 1:
The patent replaces the conventional rigid operating sheath with a flexible sheath made of materials such as shape memory alloy, nitinol, or superelastic materials. This flexible sheath can deform to accommodate instrument maneuvers without exerting constant pressure on surrounding brain tissue, while still maintaining structural integrity and passageway stability during the procedure.
Solution Approach 2:
The sheath transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape and size. The flexible sheath allows temporary deformation when instruments are manipulated and returns to its original configuration, providing both stability and adaptability throughout the surgical procedure.
2Stability of the object's composition
If a rigid operating sheath with fixed small size is used, then the sheath maintains a defined passageway, but it accepts only very small instruments and prevents simultaneous use of multiple instruments
Solution Approach 1:
The flexible sheath can expand and deform to accommodate various instrument sizes and configurations. Unlike rigid sheaths with fixed dimensions, the flexible material allows multiple instruments of different sizes to be introduced simultaneously through the same passageway without compromising structural integrity.
Solution Approach 2:
The sheath dynamically adapts its internal space to accommodate different instrument combinations. When instruments are inserted, the flexible sheath deforms to make space, and when instruments are removed or repositioned, it returns to its original configuration, enabling versatile instrument access throughout the procedure.
3Stability of the object's composition
If a rigid operating sheath is used, then the sheath provides a stable tunnel, but instruments cannot maneuver significantly without moving the sheath and pushing/retracting surrounding tissue
Solution Approach 1:
The flexible sheath absorbs the mechanical stresses and forces generated during instrument maneuvers. When instruments are moved or angled within the sheath, the flexible material deforms locally to accommodate these movements without transmitting forces to the surrounding brain tissue, unlike rigid sheaths that force the entire structure to move.
Solution Approach 2:
The sheath provides dynamic compliance during instrument manipulation. It allows localized deformation when instruments are repositioned or angled, while maintaining overall tunnel stability. This dynamic behavior enables significant instrument maneuverability without compromising the stability of the surgical passageway or causing tissue displacement.
4Stability of the object's composition
If conventional rigid sheaths are used, then the sheath provides a fixed passageway, but it requires small drilled skull openings and limits the size of surgical access tunnels
Solution Approach 1:
The flexible sheath can be introduced through smaller initial openings and then expanded within the brain tissue to create a larger functional passageway. The flexible material allows the sheath to conform to the drilled opening size while providing a larger effective lumen for instrument access compared to rigid sheaths of the same external diameter.
Solution Approach 2:
The sheath transitions from a compressed state during insertion through the skull opening to an expanded state within the brain tissue. This dynamic size change allows small surgical access tunnels to accommodate larger instrument passages, effectively decoupling the size of the skull opening from the size of the functional surgical tunnel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexible sheath system provides a larger access pathway for neurosurgical instruments, allowing safe and efficient procedures by minimizing tissue disruption and enabling simultaneous use of multiple instruments, thus enhancing the precision and safety of neuroendoscopic surgeries.
Implementation Method 1
The flexible sheath is periodically deformable in response to biasing forces from surgical instruments, such that the periodic deformation relieves constant pressure on the surgical tissue
Data Source
AI summary
A flexible surgical sheath and multi-part insertion cannula for inserting the flexible sheath in a cranial surgical tunnel for gaining access to a ventricle or other surgical target. An obturator or other elongated insertion member drives a sheath assembly into a surgical recess, typically a hole drilled through the skull and brain of the surgical patient. The inserted sheath assembly includes two or more rigid sheath portions disposed around the obturator. The obturator has a tapered or angled tip for guiding the sheath assembly through the surgical tunnel to a target region such as a ventricle or other brain structure for which surgical intervention is sought. Following insertion, the obturator is withdrawn and a flexible sheath inserted in an insertion tunnel defined by the rigid sheath portions.