The Cincinnati region’s inventory of neuroscience institutes doubled Tuesday with the announcement that TriHealth and Mayfield Brain & Spine are partnering to spend at least $40 million to expand the medical specialty through the hospital system.

The announcement came three months after Mayfield ended its 35-year relationship with the University of Cincinnati College of Medicine, which now is building the UC Gardner Neuroscience Institute on Martin Luther King Jr. Boulevard in Corryville.

Leaders of TriHealth and Mayfield said Tuesday the plan is to build and staff facilities at TriHealth’s Good Samaritan Hospital, including new neuroscience intensive care and step-down units with new equipment.

From Good Samaritan, located in University Heights and less a mile away from the new UC institute, Mayfield and TriHealth could spread the research and clinical work to other TriHealth hospitals. The hospitals or emergency rooms include Bethesda North in Montgomery, Bethesda Butler, Bethesda Arrow Springs in Lebanon, Good Samaritan in Colerain Township and McCullough-Hyde Memorial in Oxford.

Mark Clement, TriHealth’s president and chief executive officer, and Dr. Andrew Ringer, Mayfield’s director of cerebrovascular surgery, said Tuesday that the two institutions had long discussed a more formal and expanded collaboration. The two men said the need for more neuroscience options grows as the region’s population ages.

“TriHealth has been on a journey, since its founding, to be less of a network of hospitals and more of an integrated system of care made up of hospitals, ambulatory facilities and physicians,” Clement said. “This relationship of Mayfield Clinic is intended to create a system-wide neuroscience service line delivered across our hospitals, depending on…