Feature | August 21, 2013

Robot Treats Brain Clots with Steerable Needles

For the last four years, a team at Vanderbilt University has been developing a steerable needle system for “transnasal” surgery

August 21, 2013 — The idea that surgery to relieve the pressure caused by hemorrhaging in the brain is a perfect job for a robotic system is the basic premise of a new image-guided surgical system under development at Vanderbilt University. It employs steerable needles about the size of those used for biopsies to penetrate the brain with minimal damage and suction away the blood clot that has formed.

The system is described in an article accepted for publication in the journal IEEE Transactions on Biomedical Engineering. It is the product of an ongoing collaboration between a team of engineers and physicians headed by Robert J. Webster III, assistant professor, and Kyle Weaver, assistant professor of neurological surgery.

For the last four years, Webster’s team has been developing a steerable needle system for “transnasal” surgery: operations to remove tumors in the pituitary gland and at the skull base that traditionally involve cutting large openings in a patient’s skull and/or face. Studies have shown that using an endoscope to go through the nasal cavity is less traumatic, but the procedure is so difficult that only a handful of surgeons have mastered it.

Webster’s design, which he calls an active cannula, consists of a series of thin, nested tubes. Each tube has a different intrinsic curvature. By precisely rotating, extending and retracting these tubes, an operator can steer the tip in different directions, allowing it to follow a curving path through the body. The single needle system required for removing brain clots was actually much simpler than the multi-needle transnasal system.

The brain-clot system only needs two tubes: a straight outer tube and a curved inner tube. Both are less than 1/20th  of an inch in diameter. When a computed tomography (CT) scan has determined the location of the blood clot, the surgeon determines the best point on the skull and the proper insertion angle for the probe. The angle is dialed into a fixture, called a trajectory stem, which is attached to the skull immediately above a small hole that has been drilled to enable the needle to pass into the patient’s brain.

The surgeon positions the robot so it can insert the straight outer tube through the trajectory stem and into the brain. He also selects the small inner tube with the curvature that best matches the size and shape of the clot, attaches a suction pump to its external end and places it in the outer tube.

Guided by the CT scan, the robot inserts the outer tube into the brain until it reaches the outer surface of the clot. Then it extends the curved, inner tube into the clot’s interior. The pump is turned on and the tube begins acting like a tiny vacuum cleaner, sucking out the material. The robot moves the tip around the interior of the clot, controlling its motion by rotating, extending and retracting the tubes. According to the feasibility studies the researchers have performed, the robot can remove up to 92 percent of simulated blood clots.

“The trickiest part of the operation comes after you have removed a substantial amount of the clot. External pressure can cause the edges of the clot to partially collapse making it difficult to keep track of the clot’s boundaries,” said Webster.

The goal of a future project is to add ultrasound imaging combined with a computer model of how brain tissue deforms to ensure that all of the desired clot material can be removed safely and effectively.

For more information: www.vanderbilt.edu

Related Content

coherex Wave Crest LAA Occluder

Coherex WaveCrest Left Atrial Appendage (LAA) Occlusion System.

News | November 24, 2015
November 24, 2015 — Biosense Webster announced it has acquired Coherex Medical Inc., a privately held medical device
Feature | Cath Lab| November 24, 2015
November 24, 2015 — The U.S.
Boston Scientific, Watchman FLX, LAA closure device, CE mark, first European implants

Image courtesy of Boston Scientific

News | Left Atrial Appendage (LAA) Occluders| November 20, 2015
Boston Scientific announced the first implants of the Watchman FLX left atrial appendage closure (LAAC) device
News | Cath Lab| November 10, 2015
TherOx Inc. announced it has received U.S. Food and Drug Administration (FDA) Investigational Device Exemption (IDE)...
Sponsored Content | Videos | TCT| November 05, 2015
DAIC Editor Dave Fornell offers his choices for the most innovative new interventional cardiovascular technologies pr
Sponsored Content | Videos | TCT| November 05, 2015
Tom Watson, clinical analyst for MDBuyLine, and DAIC Dave Fornell discuss some of the technology trends at the 2015 T
CSI, OPTIMIZE study, peripheral orbital atherectomy system, peripheral artery disease, PAD

Diamondback 360 orbital atherectomy system. Image courtesy of Cardiovascular Systems Inc.

News | Atherectomy Devices| November 03, 2015
Cardiovascular Systems Inc. (CSI) announced last week that the first two patients have been enrolled in its OPTIMIZE,...
StopAfib.org, atrial fibrillation, AF-related stroke, patient engagement materials

Infographic courtesy of StopAfib.org

News | Stroke| November 03, 2015
In recognition of World Stroke Day, the patient-focused organization StopAfib.org launched a diverse set of materials...
Overlay Init