Based on reports, Katsuyori Shibata suffered an injury during his main event match with Kazuchika Okada at NJPW’s Sakura Genesis over the weekend.
The injury was sustained when Shibata hit Okada with a stiff headbutt, which caused Shibata to start bleeding from the forehead.
NJPW issued a stated on their English website that Shibata was taken to the hospital after the match and that he was diagnosed with a subdural hematoma and underwent successful surgery.
A subdural hematoma is a collection of blood outside the brain and are usually caused by severe head injuries. The bleeding and increased pressure on the brain from a subdural hematoma can be life-threatening. Some subdural hematomas stop and resolve spontaneously; others require surgical drainage which Shibata required.
Here was the head butt in question: