Portrait of Casey Condon, a lacrosse player from Port Washington,...

Portrait of Casey Condon, a lacrosse player from Port Washington, who suffered a concussion in March and is being home schooled as she still can't go back to school. (May 12, 2011) Credit: Newsday / Karen Wiles Stabile

Casey Condon, a senior lacrosse player at Port Washington High School, chased after the ball that whistled through the air. She didn't see the other girl coming.

The sound of the impact was so loud that the coach of her team, Raquel Piraino, standing on the other side of the field, heard what sounded like a "football hit."

Condon slammed heads with the other girl. She picked herself up and, not displaying any overt concussion symptoms to her coaches, stayed in the game.

"I felt dizzy at first and in pain, but I guess I had a lot of adrenaline because I just got right up," said Condon, 17, of the March 24 incident. The other girl was not hurt. "I didn't think much of it."

The next day, everything changed when Condon was diagnosed by the school's athletic trainer with a concussion, said her mother, Carol-Anne Condon.

That was the beginning of her ordeal.

Condon has been at home since the collision. She will graduate this month, the last few months of her senior year spent away from her friends and the classroom. The constant headaches, sensitivity to light and overall sluggishness have been debilitating.

Carol-Anne Condon said that a medical examination a week after the collision showed that her daughter's brain had been "shaken like a snow globe." The medical advice was to let "the pieces settle" and do nothing strenuous.

The Condons have struggled to cope as their oldest daughter transformed from a very active teen to someone who avoids anything that might trigger another headache. That's meant no reading, texting, Facebook, or even walking her dog, Riley, Mostly, she just slept -- sometimes 21 out of 24 hours.

How long this lasts is anyone's guess. "It could be a couple months or a year," said her father, Ed Condon.

Carol-Anne Condon said she hadn't arrived at the game when the collision happened. After she drove Casey home that evening, her daughter went right to bed. Later that night, she complained about a headache. The next morning, she felt well enough to go to school.

But once she was in the classroom, the everyday noise started bothering her. Soon the team's trainer, Rick Zappala, was on the phone with Carol-Anne Condon talking about concussions.

Zappala said that Casey's was "probably the worst concussion case I've been involved with" in 32 years as a trainer. Her mother said Casey experienced everything from chronic migraines to a loss of appetite. She became lethargic and was struggling with her balance and short-term recall. Two days after the collision, when their daughter's symptoms did not improve, the Condons took her to the hospital to get checked out.

The family's next step was to bring Casey to a pediatric neurologist. They landed an appointment a week after the collision took place. And that's when the neurologist told the Condons to have Casey "completely shut everything down, rest the eyes and have no stimulation, not even reading," her mother said.

So she spent most of her day in a darkened room, away from her parents, her sister Erin, 15, and brother Edward, 13.

And in those rare times when Casey would join the family in a room, Carol-Anne Condon said everyone had to be mindful that even the slightest noise might trigger pain for Casey.

Casey described her personality as "sad" and "very irritable" in the days and weeks after the concussion.

Casey worked toward finishing the requirements for her diploma through home schooling. "One or two tutors come a day for an hour, but if I can only go for a half hour that day they understand," she said.

A few weeks ago she started feeling stronger and more confident. "At least now I can listen to a little music and I'm finding it easier to interact with people," she said.

Of course, it was frustrating that all of this was taking place when Casey's high school years were ending and she was waiting on word as to what college she would attend. She was accepted into eight schools and decided to go to Roger Williams University in Rhode Island, where she is not planning to play lacrosse. Her parents are crossing their fingers that she will be healthy enough to go to the university when she is due to enroll in July.

Last week, Casey felt strong enough to attend a school lacrosse game. She told her mother loud cheering was tough on her.

Port Washington's prom is June 24, and the Condon family is doing everything it can to make sure she can attend.The parents think they're going to have to go with her, and she may need to wear earplugs.

"She's missed out on all the fun of the last quarter of high school, all the cool stuff," Carol-Anne Condon said. "She's frustrated . . . She's an active child that was social and her life came to a screeching halt."