For neurosurgeons, practicing a procedure before diving into the real thing is kind of like a golfer taking a practice swing. That's the analogy offered by Alan Cohen, professor of neurosurgery at the Johns Hopkins School of Medicine. But using cadavers for this purpose has its limitations, namely the expense and an imprecise imitation of brain surgery itself. So Cohen and his team tapped 3D printing technology and some Hollywood special effects experts to craft a lifelike head for better surgery simulation, complete with the texture of the skull and brain tissue.

The versatility of 3D printing technology means that it is poised to impact all kinds of industries, but one field where it is already playing a big role is medicine. That's because with 3D modelling, scientists can create anatomically-correct body parts – if somebody needs a part of a knee, heel or jaw replaced, bespoke implants can be made to fit with unprecedented precision.

And it is also helping on the preparation side of things. Back in 2014, researchers at the University of Louisville 3D printed a model of 14-month-year-old's heart, allowing them to carefully plan for an upcoming surgery. In the same year, researchers in Australia developed highly-realistic 3D-printed cadaver body parts as a way of teaching anatomy.

The latest research project from Johns Hopkins follows a similar line of educational thinking, but with more of a hands-on approach. Cadavers are typically used for surgical training, but they are expensive, not always accessible, and Cohen says they don't properly mimic the delicacy and hand-eye coordination needed to carry out something called an endoscopic third ventriculostomy (EVT).

This procedure sees endoscopes inserted into the brain to treat a condition called hydrocephalus, by draining cerebrospinal fluid and relieving pressure. The tubes redirect this fluid back into regular, safe channels within the brain, and the procedure is described as minimally invasive. Still, Cohen calls it "Nintendo Neurosurgery" because it takes a special kind of hand-eye coordination that can't be fully recreated with a cadaver.

So he and his colleagues teamed up with 3D printing and special effects professionals to come up with an improved training tool. This led them to develop a full-scale model of a 14-year-old child's head, who was a real patient with hydrocephalus.

The head is said to be lifelike, in that it is full-size and features the touch and feel of the human skull and brain tissue. It also has a few fancy additions, including an electronic pump to replicate flowing cerebrospinal fluid and brain pulsations, and one version created even includes hair and eyebrows.

Trainee neurosurgeons were then enlisted to test the device, including 13 medical residents and four more senior neurosurgery fellows. When asked to rate the simulator, the participants gave it consistently high scores for both its lifelike aesthetics and effectiveness as a training platform. More testing is needed to assess whether or not it actually improves performance in real-life operations, but in their 3D-printed head the team already sees multiple advantages over traditional approaches.

"With this unique assortment of investigators, we were able to develop a high-fidelity simulator for minimally invasive neurosurgery that is realistic, reliable, reusable and cost-effective," says Cohen. "The models can be designed to be patient-specific, enabling the surgeon to practice the operation before going into the operating room."

The research was published in the Journal of Neurosurgery.

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