His brain felt like a ripe melon "ready to blow up."

Former Maryland fullback Tim Cesa switched helmets four times during the 2006 season in search of one that would protect his head from additional concussions.

None of them helped.

After a series of five or six concussions over almost two seasons, Cesa's career ended with a final hit on the first play against Florida State on Oct. 28, 2006. Now, as a manager at R.J. Bentley's Filling Station, Cesa's only tie to the football program is through fans who pack the popular downtown bar.

It's the only connection he can handle while he finishes school.

Adam Waddell's football career at Johns Hopkins came to a screeching halt when he dived for a pass in practice last summer and didn't get up. What appeared to be insignificant contact with the artificial turf at Homewood Field became, by Waddell's estimate, the 10th concussion he suffered since seventh-grade flag football.

Cesa and Waddell serve as sobering reminders of the risk inherent in multiple head traumas. It's a lesson not lost on Maryland quarterback Jordan Steffy, who suffered his latest in a series of concussions Sept. 29 against Rutgers and has not started since. Steffy won't start in Friday's Emerald Bowl against Oregon State but has appeared in the Terps' past two games.

The medical community is still trying to understand the lingering aftereffects and long-term implications of mild traumatic brain injury. Players of all age groups - from peewee leagues to the NFL - are finally realizing the hazards of an injury that has been misdiagnosed and underreported for years.

In the interest of returning to the field, players are quick to dismiss symptoms that should set off alarms. Too often, they risk more trauma because of misperception or stubbornness.

Waddell, a quarterback who moved to wide receiver his junior year, came to the realization that each concussion he endured made him more vulnerable to the next. He says at least four of his concussions have been significant.

"I thought this was just something that happened in football, and I thought other kids were having it just as much," he said. "It wasn't until I came to Hopkins and had two decently strong concussions that they actually gave me some tests. Then I realized normal kids aren't going through what I'm going through. Normal kids aren't getting knocked out in a play, coming to real quick and continuing to play."

'You just can't stop it'

Steffy has had four concussions - two at Maryland, and two in high school. He was cleared to play four weeks after the last one but didn't get on the field for three more weeks.

"Everything we've always been taught as football players is to stretch it to the limits," Cesa said. "But this is one thing you just can't stretch to the limits. You have to get out while you can, or you're looking at a poor quality of life later down the road."

Why is it worth the risk for Steffy?

"Good question," Steffy said. "I don't know. There's such a fine line between fighting through something and being stupid. At this point, obviously yes, I've had several concussions and there's a risk, but I have faith in God. I've been praying, and I haven't felt that it's my time to stop yet."

He also has no way to decrease the chances of another one.

Said Cesa: "He can wear an army tank on his head. I wore every helmet we could buy. You just can't stop it. It's always going to be there."

Cesa won't go near the stadium and can't bear to watch the games. He lost interest in the sport, lost the direction in his life and fears some former teammates are facing the same downward spiral.

"In the end, the doctors don't know. [Maryland coach] Ralph Friedgen doesn't know. Even your teammates don't know," Cesa said. "You're the only one that knows how you feel. When I was telling everybody I was OK and I could play, I was the only one that knew I really probably shouldn't be playing."

The agenda of an injured player is to get back on the field as soon as possible. In Altoona, Pa., where Waddell grew up, he was no different. When he suffered a severe concussion in 11th grade, he had to pass prescribed tests to play again. One test was to run 800 yards without getting dizzy or nauseated.

"I was just trying to find a way to run the 800," Waddell said. "When you're young, you don't even realize what a concussion really is. You don't understand the implications of how severe a concussion can really be."

It wasn't until Waddell went to Hopkins that he got the message. In 2006, his sophomore season, he suffered concussions two weeks apart. The first time, he was knocked unconscious by a thrown ball while sitting out practice. The second came on helmet-to-helmet contact in a game and left him with blurred vision.

Both times, he was sent to the hospital for tests by Matt Bussman, Hopkins' associate athletic trainer.

"With Adam, his symptoms would resolve very quickly," Bussman said. "[But] each time you have a head injury, you are more susceptible. You kind of have to start adding them up."

Waddell and his parents huddled with experts. A team of Dr. Andrew Cosgarea, Hopkins' head physician; Dr. Brian Krabak, who worked with Hopkins sports medicine; and Dr. Andrew Tucker, the Ravens' head physician and a member of the NFL's concussion committee, studied his case.

They determined it would not be inappropriate for Waddell to play again. He was cleared Oct. 4 but knew another concussion would likely end his career.

The final one came during camp drills last August when Waddell struck his head diving for a pass. Bussman, standing a few feet away, thought Waddell had his wind knocked out at first. Then Bussman realized it was more serious. So did coach Jim Margraff.

"That's a hit that every other kid would've popped right back up with," Margraff said. "And he didn't. Common sense says he's reacting to these hits differently than other guys."

That night, Waddell phoned his parents with the news. Randy and Pam Waddell had little knowledge of concussions at first but learned more with each doctor's visit. When the call came this time, Waddell's father knew football was finished.

"It is scary, because what's the long term?" Randy Waddell said. "We honestly felt we got Adam [out] at a good time. ... I'm not the gambling type. If it happened again, I couldn't live with that."

'Unlike any other injury'

Cesa was a dean's list student his freshman year and took pride in his 3.6 grade point average. He made the transition from linebacker to fullback in 2005 and became the Terps' lead blocker.

Near the end of his redshirt sophomore season in 2005, he got his first few mild concussions. As Waddell did, Cesa thought it was typical.

"I'd hit somebody and then you're dazed and confused for a few minutes and then come back down to a normal state," he said. "I kept playing through them. The whole time, I'm thinking I'm a fullback, I'm a football player, this stuff happens, you're just getting shaken up a bit. At the same time, because of how little information is out there on them, I didn't know I was ending my career."

On Oct. 14, 2006, Cesa took a hit at Virginia that changed everything. After that, he couldn't hide the effects anymore. He couldn't run a regular play at practice without getting "dazed and confused."

There were little headaches that turned into migraines, followed by memory loss. One week after the hit at Virginia, after the homecoming game against North Carolina State, Cesa found himself in the locker room wondering what was going on. He was dizzy, and his head was pounding.

"The next week at practice, I could barely hit people," he said. "Of course, me being as stubborn as I am, I still went out and tried to play. I made it through like one series. After that happened, [Dr. Yvette] Rooks basically sat me down and said 'You're done for the year.'"

Rooks, who has been Maryland's primary care physician for the past decade, said athletes have to be free of all symptoms - no headaches, no sensitivity to light or ringing in the ears - not only at rest, but also during practice.

"Everyone is at risk, just like someone getting a leg fracture," she said. "If someone is cleared, they've passed the test. They can go back to their activities of daily living. I don't think we're putting them in harm's way; that's just the nature of the game."

In allowing a player to return, Rooks considers the severity and how long it has been since the last concussion. The number of concussions a person can tolerate is unclear.

"We don't know the answer in regards to how many is too many," said Craig Bennett, in his fourth season as Maryland's head team physician and orthopedic surgeon. "We know that once you've had one, you're going to be at increased risk for a period of time. The question is how long is that period of time? That's the million-dollar thing. What's clear is in [Steffy's] case, he has recovered from his most recent one. He's OK to go back. Is he at increased risk? Absolutely."

Steffy said he is prepared for the consequences.

"It's a risk, I know it, but at this point, I feel like I'm going to continue to keep fighting and what happens will happen," Steffy said. "They say I'm clear, so I'm going to go out and give it everything I have."

It's an option Cesa no longer has.

"It's unlike any other injury because it's your brain," Cesa said. "It's not a muscle, it's not a bone. Nothing heals. My head will never heal."

ken.murray@baltsun.com