Most people who use a wheelchair prefer smooth pavement, but 16-year-old Kellisa Cain has always wanted the ground beneath her to be rocky, bumpy and “crazy,” her father said.

Kellisa, who lives in Jacksonville, Fla., with her mom, Lisa, her sister, Laurel, and her father, Chris, has hydrocephalus and cerebral palsy— conditions that have left her developmentally delayed, prone to seizures, and reliant on assistive devices. Doctors didn’t expect Kellisa would survive long after birth, but when she did, Chris promised her that despite any potential health complications in the future, he’d make sure she lived the most normal life possible. He also vowed to show her the world.  

Since then, the wheels of Kellisa’s jog strollers have touched the soil at Great Smoky National Park, the red clay at national parks in Sedona and the Grand Canyon, and the grass on an island off Lake Superior. She’s visited 47 of the 50 states that her father wants her to see by the time she is 18.

“We started out with just the wheelchair, and I’ll be honest with you: We were on trails we had no business being on in a wheelchair,” Chris, 44, told FoxNews.com. Outdoors, he said, Kellisa “comes alive.”

Defying the odds

“We’ve only ever seen one other kid in a wheelchair doing this stuff,” Chris said, “and it breaks my heart that other kids are trapped in their bodies and in their house. I want people to see Kellisa and know that it’s worth it.”

Kellisa’s twin sister passed away 27 days after birth, but doctors predicted Kellisa was the one who wouldn’t make it. The girls were born premature at 25 weeks and with twin-to-twin transfusion syndrome, which occurs when twins share blood supply from a single placenta. The recipient twin— in this case, Kellisa— is born larger and takes more blood from her sibling, who is called the donor twin and is the smaller of the two. During the pregnancy, Lisa almost died.

Kellisa spent the first 16 months of her life in the ICU, and her early childhood was riddled with doctor’s visits, surgeries— 22 to this day— and prescription medications required for epilepsy. Hydrocephalus and cerebral palsy, which are common comorbidities, are marked by an excess of fluid in the brain and muscle dysfunction, respectively. At birth, extreme pressure on Kellisa’s brain led to internal bleeding and post-hemorrhagic hydrocephalus of prematurity.

“Sixteen years ago, the majority of those kids did not survive— and she did survive,” Dr. Kim Dal Porto, Kellisa’s pediatrician in Jacksonville since she was 2, told FoxNews.com.

In extremely premature babies, that internal bleeding is common but doesn’t always result in hydrocephalus, as was the case for Kellisa.  To control hydrocephalus, she uses a nonprogrammable shunt, which is a device implanted in the head and connected to a tube that empties excess cerebrospinal fluid into the abdomen. Shunts are one of the most common treatments for hydrocephalus, and as she has grown, Kellisa has had about a dozen surgeries to either replace or adjust the device.

Having more than a dozen shunt surgeries by early adulthood isn’t uncommon among hydrocephalus patients, Mark Luciano, a professor of neurosurgery and the director of the Cerebral Fluid Center at Johns Hopkins University, who has not treated Kellisa, told FoxNews.com. He said while shunts have a 5 percent infection rate and implanting them can be life threatening, taking trips by car and plane usually isn’t a problem for hydrocephalus patients so long as the shunt is functioning properly.

Dal Porto said hydrocephalus posed more of a health threat to Kellisa as a child, but today her primary diagnosis is spastic cerebral palsy, which means her muscles are too tense.

“For that, for her whole life, [Kellisa] has had tons of physical therapy and occupational therapy,” Dal Porto said. She added that Kellisa sees a GI specialist due to the feeding tube she must use to drink fluids, as well as an orthopedist for her cerebral palsy, among other specialists.

David Hammond, Kellisa’s neurologist, told FoxNews.com that Kelissa takes Lamotrigine and Topiramate to help control her seizures. Those medications have helped ward off the prolonged episodes of seizing— called status epilepticus seizures— that she had more often when she was younger. Sometimes, Kellisa still has minor episodes when her arms and legs stiffen.

On trips when Chris and Kellisa are remote from a hospital, Chris keeps the seizure rescue medication Diazepam on hand to administer to Kellisa by rectum, but he’s only done this a few times, he said.

“As long as the seizures are controlled, we want our patients to live as normal a life as possible,” Hammond said.

Starting with baby steps

Dal Porto and Hammond said Kellisa fits the mold of a typical patient with hydrocephalus and cerebral palsy, but when asked to describe what makes her different from them, they use words like “expressive,” “optimistic” and “ambitious."

“She is very tuned into cues and what other people are saying and doing,” Hammond said.

To communicate with her family, Kellisa uses a combination of sign language and uttering simple words like “yes” to indicate how she feels and what she wants.

“I feel like she is living life,” Dal Porto said. “You feel like she actually is enjoying things. She’s got music she likes, singers she likes, and friends.”

Chris knew his daughter was destined for more than being cooped up indoors when they began their slew of excursions with mild hikes in Florida.

“We started with baby steps,” Chris said, “and she would giggle and laugh, and look up at me, and at some point she would say, ‘More,’ and sign language for more.”

Throughout Kellisa’s life, the Cains have gone through five different jog strollers, not counting the device they use now and that they ordered from France. The jog stroller, a Hippocampe chair, has three rugged wheels: two larger ones in the back on either side of the seat, and a smaller one in front. It has a handle so Chris can push her, or Kellisa can wheel herself.

Before getting the Hippocampe chair, Chris would adapt jog strollers he’d buy off the shelf, replacing tires until the structures would break.

“We would do stuff, and I would notice the bumpier and harder it was, the more she liked it,” Chris said. “It could be ruts, rocks, just anything. She liked that, and that would give me the clue and the motivation to do more, and we kind of progressed and grew with what we were doing together.”

Chris credits his daughter’s sense of adventure to zipping around the state of Florida by car to attend different doctors’ appointments. That included 69-mile one-way trips from home to Arnold Palmer Hospital for Children in Orlando about four times per week from the time Kellisa was 6 months to 2 years old. When the Cains relocated to Florida from Chicago when Kellisa was an infant, they sought warmer weather to avoid exposing Kellisa’s weak lungs to bitter Midwestern winters. But because they didn’t know what was in store for her health, they didn’t know she would need to see so many specialists.

Inspired by his own childhood desire to flee urban Chicago to hike outdoors, Chris admitted that when he promised Kellisa he’d take her across the U.S., he didn’t know whether it would be attainable.

“We didn’t know whether Kellisa was going to live minute to minute, but it was something big that we could focus on,” Chris said. “I needed to focus my mind on something other than all the alarms and doctors and nurses and surgeries, and I kind of got some peace with that.”

Of all 50 U.S. states, only Iowa, Hawaii and Alaska are left.

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Releasing Kellisa from her shell

The first trip Chris took Kellisa on was to the Grand Canyon and Sedona when she was 7 years old. Later, he took her camping in Michigan off Lake Superior, then on a 25K race across Big Bend National Park in Texas.  A few years ago, he took Kellisa and her adopted sister, Laurel, to Minnesota and Wisconsin for a 2.5-mile race over the states’ frozen lakes. Chris pushed Kellisa in her jog stroller while pulling Laurel in a sled.

The most challenging excursion for Chris and Kellisa so far has been the Bataan Memorial Death March in New Mexico. The 26.2-mile race includes going through ankle-deep sand, atop gravel and rocks, and up and over a mountain. Chris had done the race three times by himself before, but in 2012 and 2014 he tried it with Kellisa. Organizers gave him permission to do it with a modified stroller with Kellisa the first time. That year, the daughter-father duo completed 20 miles, but Chris opted not to keep her out in the unseasonably warm 90-degree weather because the heat could have triggered one of Kellisa’s seizures.

“It was one of the hardest decisions I’ve ever made,” Chris said of not finishing the race, “because she wanted to keep going, and she said, ‘More, more, more!’ and she was pointing to the people going ahead of us. It broke my heart, but I knew it wasn’t worth the risk.”

In 2014, they didn’t get to begin the race because Kellisa had a prolonged seizure in the tent where the two were camping at the starting line. At that point, Chris had to administer Kellisa’s seizure rescue medication.

“It was just bad timing,” Chris said. He plans to take Kellisa back to New Mexico next year for a third try at the race.

Hammond, Kellisa’s neurologist, said he’s never advised Chris against taking a particular trip with Kellisa, but only that he keeps her Diazepam on hand and to use the same judgment any loving parent would when doing an activity with his or her child.

He described Chris as a “very caring person” who wants to “give [Kellisa] every benefit he can.”

“This is a family who has become very experienced over the years in seizures and management of seizures,” Hammond said. “They’ve been given the principles and general approaches to apply in choosing safe activities and knowing what to do should a major convulsive seizure occur.”

While many families at home are skeptical of Chris’ decision to take his daughter on road and plane trips, it’s different in the racing community, Chris said.

“When we’re out in the regular public, [Kellisa] so desperately wants to say, ‘Hi,’ and a lot of people shy away,” Chris explained. “In the outdoor community, it’s just the opposite. They pat her on the back and say, ‘Good job.’”

Chris plans to take Kellisa to Iowa during the first half of next year, but he hasn’t yet mapped out that trip. He wants to do a combined trip to Alaska and Hawaii in summer 2016.

In Alaska, Chris plans to drive north of the Arctic Circle on a dirt road that reaches the Bering Sea, and in Hawaii he wants to drive her to the highest mountain that surpasses 13,000 feet.

“People, if they see and hear some of the stuff we do … people could have the tendency to say I’m dragging Kellisa along, but it’s the exact opposite: She’s dragging me along.”

“She comes out of her shell when she’s doing this stuff,” he said. “She comes alive.”