Sensor technology: sensitive spatula protects the brain

Brain surgery is arguably the most complex procedure in the operating room as surgeons can quickly cause unintentional damage. The culprit are not just surgical cuts (incisions) a surgeon needs to actively make, but might also be passively used instruments. This includes spatula-like retractors used to manipulate tissue and/or hold it in place. Sensor technology is designed to offer assistance in this case and alert the surgeon.

In this COMPAMED-tradefair.com interview, Prof. Markus Seidel and Marcus Löffler talk about the use of spatulas in brain surgery, discuss the risks and explain how they can be avoided.

Prof. Seidel, Mr. Löffler, we are talking about the development of a sensor-equipped, surgical brain spatula. What is the purpose of this surgical instrument?

Prof. Markus Seidel: The first step when it comes to surgical procedures in deep brain regions is to gain access. The surgeon makes an opening in the skull, while tissue around the surgical site must be pushed to the side and held in place. Surgeons typically use a brain spatula for this. This device is a malleable metal strip that is shaped by the surgeon and then fastened to maintain access to the brain.

Marcus Löffler: The spatula can cause so-called traumatic retractions in the tissue. Positioning the spatula with too much pressure or prolonged excessive pressure on the tissue may cause injury or lack of sufficient blood flow to the tissue. The consequences can sometimes be more severe than those affected by the actual procedure. We aim to prevent these types of secondary injuries by measuring the forces the spatula exerts on the tissue and alerting the neurosurgeon.

What exactly do you want to measure in this scenario?

Seidel: On the one hand, we want to measure the applied pressure when the spatula is put in place and alert the surgeon if too much pressure is being exerted in an effort to relieve it. On the other hand, we also want to track the continued pressure on the tissue during the intervention, allowing the surgeon to monitor and assess it.

Today’s brain spatulas have been used as surgical tools for many years. Neurosurgeons know how to use them and are very aware of their limitations and risks. Our idea is to use sensor technology to provide another tool for this type of assessment. The goal is to make it easier for the surgeon to determine when the instrument needs to be removed or repositioned.

What is the greater risk of this surgery – if the pressure is too much or if it is being exerted too long?

Seidel: Both aspects play a role. Several studies show that the brain tissue tends to adapt when the spatula is positioned with slightly more pressure. That being said, the surgeon must always avoid pressure spikes – meaning short, strong forces acting on the brain tissue. Meanwhile, other studies indicate that the spatula restricts blood flow when applied with light pressure and left in place for a prolonged time.

Can you envision other medical technology applications for this technology?

Löffler: We have also discussed the use of spatulas in surgery and how they facilitate access to surgical sites with our medical counterpart Prof. Dirk Winkler from the Department of Neurosurgery at the University Hospital Leipzig. Spine surgeons face similar challenges and the question is whether it is also possible to limit any secondary injuries by monitoring and visualizing the amount of exerted force and stress in this setting. As you can see, this set of problems is by no means limited to brain surgery.

What are the next steps in this project?

Löffler: Right now, our industry partner, Micro-Hybrid Electronic GmbH in Hermsdorf, is developing the hardware. I am sure we can soon proceed to conduct the first tests and develop the data analysis software. We then want to use the first prototype to study the possibilities and limitations of the sensor-based spatula.

Seidel: We have already set up a test site here in Zwickau to conduct automated measurements. Later on, we want to study the forces exerted in animal models.

Löffler: This will once again be done in collaboration with the Department of Neurosurgery at the University Hospital Leipzig. As of now, the project will conclude by the end of 2020. The upcoming tests will reveal other possibilities and options that might result from these assessments.