SAN FRANCISCO -- A Giants fan who was brutally beaten on opening day at Dodger Stadium is opening his eyes but remains in critical condition at San Francisco General Hospital, the medical center's chief neurosurgeon said Wednesday.

Bryan Stow has been weaned off one of five anti-seizure medications since arriving Monday from a Los Angeles hospital where he had been in a coma after being attacked in March, Dr. Geoff Manley said. Stow's brain also did not show any seizure activity during 30 hours of continuous monitoring in the hospital's intensive care unit.

Manley described these developments as positive but could not predict Stow's chances for recovery.

"We just don't know right now," he said. "We're treating him as if he will make a recovery. We're being very aggressive. We're leaving no stone unturned. But time will tell."

The goal over the next several weeks is to taper the remaining medications to better assess damage to Stow's brain, Manley said. Los Angeles doctors had placed Stow in a medically induced coma in what Manley called an "epic struggle" to control his seizures, which can result in further brain injury.

Stow, a 42-year-old paramedic and father of two, wore a Giants jersey to the March 31 season opener in Los Angeles and was attacked by two men in Dodgers gear in a parking lot after the game. No arrests have been made.

Los Angeles Police Chief Charlie Beck said Tuesday the Dodgers have offered an additional $100,000 for information leading to the suspects' arrest. The total reward being offered now stands at more than $200,000.

Detectives are looking into about 500 leads in their search for the attackers, Beck said.

Doctors were concerned about possible further injury to Stow's brain while he was being transported from Los Angeles to San Francisco General's internationally recognized brain trauma unit. But Manley said Stow suffered no complications on the trip.

The difficulty in predicting Stow's chances of recovery stems from doctors' limited understanding of the science of traumatic brain injury, which Manely said was comparable to researchers' level of medical knowledge about cancer and heart disease 40 or 50 years ago.