Training neurosurgeons in a rare hydrocephalus procedure, with a little help from Hollywood

ETV trainer

A 4-year-old has a progressively enlarging head and loss of developmental milestones: a clear case of hydrocephalus. He undergoes a minimally invasive endoscopic third ventriculostomy (ETV) to drain off the trapped cerebrospinal fluid.

This requires puncturing the floor of the brain’s third ventricle (fluid-filled cavity) with an endoscope — while avoiding a lethal tear in the basilar artery, which lies perilously close.

There are no good neurosurgical training models for this rare and scary operation.

“We semi-blindly poke a hole through the ventricle floor,” says Benjamin Warf, MD, director of Neonatal and Congenital Anomaly Neurosurgery at Boston Children’s Hospital. “To make the technique safer and to be able to train more people, it would be very helpful to make that hole in a way that’s less anxiety-provoking.”

Cadavers don’t properly capture the technical demands of the task. So currently, neurosurgical residents and fellows are forced to practice by performing a “seed-ectomy” on (wait for it…) a bell pepper.

That’s where some very high-end special effects come in. Boston Children’s Simulator Program, SIMPeds, collaborated with hospital neurosurgeons and a Hollywood special effects company, Fractured FX, to create several ultra-high-fidelity trainers. They include this ETV trainer, which captures the visual and tactile properties of the real operation:

Published by JNS Pediatrics on Vimeo with permission.

Reproducing reality

The trainer was based on MRI studies of another patient: a 14-year-old with hydrocephalus due to fourth ventricle outlet obstruction. It was built through a combination of 3D printing technology and casting processes, using special gels to simulate the feel of real membranes and brain tissue.

It also reproduces the pulsations of the basilar artery, brain ventricles and cerebrospinal fluid, making the operation feel like an ETV on an actual patient.

ETV trainer
At left, a simulated brain endoscopy view. At right, a 3D-printed brainstem and basilar artery with its branches and arachnoid membranes. (Click above and below to enlarge)

Even seemingly irrelevant details like the scalp were rendered in lifelike detail to keep the experience as realistic as possible for trainees. Its development was supported by a grant from the Boston Investment Conference.

ETV trainer

In a study published in Journal of Neurosurgery: Pediatrics in April, four neurosurgery fellows and 13 medical residents performed ETV simulations with the trainer. They consistently gave it high ratings for realism: On a five-point scale, the simulator averaged 4.88 for its effectiveness in training and 4.69 for its aesthetic features. Neurosurgeons were able to gauge trainees’ skill level (novice versus expert) based on how they performed during the simulations.

Going big with the ETV trainer

Before sharing the trainer more broadly, Warf plans to add more capabilities, together with a training curriculum.

“We have begun the process of expanding the ETV trainer into a more complete model that can be used for training in the use of flexible neuroendoscopy,” he says.

Future versions will also replicate ETV’s sister operation, choroid plexus cauterization (CPC). CPC burns the choroid plexus, the tissue that produces cerebrospinal fluid, in two of the brain’s four ventricles. This decreases the amount of fluid produced, boosting the success of ETV.

“The final model will greatly improve our capacity to prepare residents and fellows here in Boston, as well as trainees in our CURE Hydrocephalus program in Uganda, ahead of their experience in the operating room,” Warf says. “The ultimate goal is to enhance and accelerate training in ETV/CPC and other techniques with a model that is durable, reusable and affordable.”

In this TED talk, SIMPeds director Peter Weinstock, MD, PhD, explains how special-effects-augmented simulations can help surgeons “practice before game time”:

Learn more about the Boston Children’s SIMPeds Program.