The 18-year-old Lincoln High School senior hit by a car while running in the Portland to Coast High School Challenge relay apparently sustained a stroke from the crash, according to the girl's mother.

Arlene Green said her daughter, Chelsee Jean Caskey, also has a tear in her carotid artery, making surgery for other injuries risky. She said doctors discovered the stroke.

Court documents obtained by KGW reveal that police believe a driver who struck and critically injured a teen runner in the Hood to Coast Relay was high on meth and marijuana at the time.

Chrystal Marie Meyer, 20, from Rainier, was arrested Sunday night and transported to Multnomah County Jail, said Oregon State Police Lieutenant Gregg Hastings.

Meyer pleaded not guilty Monday to charges of assault, reckless driving and driving under the influence of intoxicants. Court records alleged she was on methamphetamine and marijuana at the time of the crash.

Chelsee Caskey, the Lincoln High School student struck Friday night, is expected to survive, according to family.

Just after 9 p.m. Friday, the 18-year-old Caskey was running on the northbound shoulder of Highway 30, near Rocky Point Road, when she was struck from behind by a northbound Kia Rio, police said.

Her mother believes it's a miracle Chelsee survived.

"She's gonna make it. It's going be a lot of hard work," Arlene Green told KGW.

Caskey's head hit the windsheild and she was carried on the hood of the car until it crashed through a fence, authorities said.

After the collision, the Kia Rio continued about 50 feet down an embankment.

MySpace photo

Chelsee Caskey

Both Caskey and Meyer were transported to Legacy Emanuel Hospital.

Caskey was listed in serious condition in the hospital's intensive care unit. She suffered a broken leg, broken ribs and serious internal injuries.

Troopers said she was wearing a reflective vest and using a runner's headlamp. Caskey was running for the Lincoln High School Hood to Coast Relay team.

Meyer suffered minor injuries, according to Hastings.

More: Statement from Hood to Coast organizers

Hood to Coast organizers said this was the first accident of its kind in the relay's 27-year history.

Also: Hood to Coast pictures, results

The Associated Press contributed to this report.