Ceramic implant opens brain to ultrasound therapies

Engineers have created a ceramic skull implant that will allow doctors to deliver ultrasound therapies into the brain, an advance that could improve outcomes for patients with neurological diseases.

Ceramic cranial implant gives ultrasound access to brain (UC Riverside)
Ceramic cranial implant gives ultrasound access to brain (UC Riverside)

Developed by researchers at the University of California, Riverside, the implant will let doctors deliver ultrasound treatments on demand and on a recurring basis. A paper describing the research has been published in Advanced Healthcare Materials.

Guillermo Aguilar, professor and chair of mechanical engineering at UCR’s Bourns College of Engineering, and Javier E Garay, professor of mechanical and aerospace engineering in UC San Diego’s Jacobs School of Engineering, led the project.

Ultrasound can be used to treat a variety of brain disorders, including Alzheimer’s and Parkinson’s diseases. It can also be used to destroy cancer cells, dissolve blood clots during stroke, and open the blood-brain barrier for enhanced drug delivery.

The cranium, however, is usually between 2 and 8mm thick and relatively dense, so sound waves are either reflected or absorbed before penetrating the brain.

To help doctors deliver therapeutic sound waves into the brain, the team developed and tested a transparent, ceramic material that could be used to replace a portion of the cranium to allow easy, targeted transmission of ultrasound waves into the brain.

The material, a new variation of the ceramic material Yttria Stabilized Zirconia (YSZ), is non-porous, allowing non-focalised, low-intensity ultrasound waves to pass through.

According to UCR, ceramic materials are biocompatible, extremely hard, and shatter resistant, making them ideal for implants. The team previously developed a YSZ cranial implant material for laser-based therapies, which is in preclinical trials. The current material could be used to deliver ultrasound and laser-based treatments.

“These materials are already being used in dental crowns and hip replacements, and our team is working to extend their application to the diagnosis and treatment of a wide variety of brain pathologies and neurological disorders,” Aguilar said.

“Developing an optically and radio-frequency transparent cranial implant was already an exciting accomplishment, and we continue to work to make this implant a reality. Now, proving that ultrasound could be transmitted through the implant could expand its therapeutic capabilities even further.”

Garay said the findings could extend the application of zirconia.

“It is important to appreciate that the zirconia we developed works well for this application because we engineered it to have low porosity. Porosity, a common defect in ceramics produced by traditional methods, significantly deteriorates ultrasound transmission as we show in this paper,” Garay said.

The UCR Office of Technology Commercialisation has filed a patent application for the technology, which was developed in collaboration with researchers from Centro de Investigación y de Estudios Avanzados (CINVESTAV) del Instituto Politécnico Nacional (IPN), in México City.

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