"Because of what happened my brain swelled up so much they had to remove part of my skull," Gunner says.
The California Interscholastic Federation, or CIF, oversees high school athletics. Injuries like Sandberg's are why the organization is restricting certain metal composite bats. Marie Ishida is the CIF executive director.
"If the ball leaves the bat at a slower speed, hopefully there will be less of a chance of a pitcher or defensive player from being injured," Ishida says.
The CIF may also require all softball and baseball pitchers to wear protective headgear beginning in 2012.