For veteran bowlers Rob and Ron Carter the perfect game is just around the corner.

So the twin brothers had no trouble convincing each other to head over to the Bangor-Brewer Bowling Lanes one day this summer even though they had vowed earlier to stay home and rest their aching bodies.

“There’s always the chance something great is going to happen – you might get your concentration back and really roll the score,” Rob Carter says.

The 51-year-old brothers, who are single and live together in a double-wide trailer in Orrington, developed a passion for bowling in high school. But the game became more than a pastime in 1988 when they were diagnosed with hereditary spastic paraparesis, a rare degenerative spinal cord disorder that makes it hard to walk and that ultimately could lead to complete immobility.

The Carters, who have a mild to moderate form of HSP, walk with a dragging motion because they have difficulty lifting their toes.

Their symptoms also include a decreased sense of balance, weakness in the legs and muscle spasms. Like many people with HSP, they experience back and knee pain, probably as a result of muscle weakness.

Since their diagnosis, the twins have come to approach bowling with a fervor that stems as much from a sense of urgency as a competitive spirit.

“If I’ve only got three years left to get more bowling in I’ve got to do it every day,” reflects Ron.

Told that exercise is vital to combat muscle stiffness and that once muscles deteriorate they probably can’t be rejuvenated, the brothers humorously invoke the motivational phrase that never was meant to be taken so literally.

“Use it or lose it,” Rob sums up.

Hoping to provide clues to the disease her sons apparently inherited, Lucy Beatham of Orrington has wracked her brains trying to recall if anyone in the family experienced the same symptoms. Her sons’ paternal grandmother once talked about an aunt who had “a lot of trouble” with her balance.

“Whether it’s the same thing, I don’t know,” she muses.

Everyone was stunned several years ago when Beatham’s youngest son, John Carter, 38, of Bucksport also was diagnosed with HSP. Since family members hadn’t been able to trace the disorder, they figured it must be something of a fluke, Rob says.

In fact, HSP is incredibly rare, with less than 10,000 documented cases in the entire country, according to the Carters’ physician, Dr. Kenneth Simone of Brewer Family Medicine.

Simone, who doesn’t know of anyone else in Maine with the disorder, says he is amazed that the twins’ symptoms continue to mirror each other’s.

“When one loses balance, the other does too. When one loses strength, the other does too,” he says. “When you have a disease that can cause five or six or seven problems, it’s almost uncanny how both diseases are so parallel.”

Diagnosed four years before his brother, Rob originally was thought to have amyotrophic lateral sclerosis, a progressive muscular disorder, also known as Lou Gehrig’s disease.

But after Ron began experiencing certain symptoms, doctors ordered more tests and subsequently changed their minds.

Although neither brother had heard of HSP, Rob considered the new diagnosis a reprieve.

“It was a relief to know it wasn’t certain death,” he says.

Others might have looked for a second opinion or a new kind of therapy.

“I just thought, hey, that’s the way it is,” Rob says.

Meanwhile, HSP not only put an end to the softball, baseball and basketball games the twins loved to play, but also spurred an early retirement from Grant’s Dairy where they worked for more than 30 years.

They miss having a job to go to each morning.

“I was looking forward to getting 40 years in with one company and building up my retirement,” Ron says.

With their condition deteriorating further every six months, the brothers can’t forget they’re living under a shadow.

“There’s no use chewing on it, we’ll just try to be mobile as long as we can,” Ron says. “We might have it bad, but there are always people who have it worse.”

And so the brothers’ days are measured in strikes and spares.

Each morning like clockwork they arrive at the bowling lanes on Wilson Street, grab a cup of coffee and embark upon a three-or-four-hour marathon that often does a job on their backs and knees.

But the inevitable physical toll doesn’t stop them from hatching an ambitious plan.

“We like to get 1,200 pins down – a 120 average for each string,” Rob says. “Before the disease we could do it if we wanted it and really went for it. Now it’s quite a bit tougher.”

A few days earlier, Ron had averaged a 104 game, but was pleased just the same.

“It’s about as good as I can do without pushing,” he says.

Gray hair carefully combed, t-shirts and jeans hanging loosely on their rail-thin bodies, the Carters look identical except for the mustache that Rob sports.

But their bowling styles are as different as night and day. Ron lets his legs do the work, bending his knees so they’re almost scraping the floor.

Meanwhile, Rob puts the power in his arm, standing straight and throwing the ball with a vengeance.

Always cognizant of their physical state, the twins are no less mindful of their mental dispositions.

“Your attitude goes down the bowling lane too,” Rob explains. “If you just get up there and have a good time you can do things you wouldn’t believe. But if you’re in a bad mood it’s hard to get a good score.”

Added Ron, “You’ve gotta have the right concentration. And you can’t let anything upset you.”

In their prime the brothers were a force to be reckoned with. Even now their competitive nature sometimes surfaces.

Ron took a moment from his own game recently to watch a group of strapping young men nearby unleash one thunderous ball after another.

“I wish I could show them what I used to be able to do,” he murmurs.

Although they have lost some agility, the brothers still exhibit remarkable endurance, said Charles Milan, owner of Bangor-Brewer Bowling Lanes.

Top conditioned athletes likely would find themselves lame if they bowled even half the number of strings the brothers undertake daily, says Milan, a former state bowling champion.

He admires the pair for another reason.

“They’ve always got a smile on their faces – you’d never know anything was wrong,” Milan says. “They’ve got a great attitude toward life. If everyone was like them there’d be no problems in the world.”

Creatures of habit, the Carters have dinner at their mother’s and stepfather’s home every afternoon. A game of Scrabble inevitably follows.

While a bowl of cold cereal will do for breakfast most of the time, on Wednesdays and Sundays it’s always hot cakes at MacDonald’s.

Never ones to socialize much, the brothers see no reason to change now, especially when their physical limitations make it even more difficult to be in a crowd.

Renting a video is much easier than stumbling all over people trying to exit a packed movie theater, they point out.

Making their way through the supermarket also is fraught with difficulty, according to the twins who no longer shop together.

“Part of it is that one of us limping around the store doesn’t draw as much attention,” Rob says.

Still, they always are happy to answer questions about their disability.

“We’d rather people ask than stand and snicker,” Rob says.

Having their story in the newspaper, the twins hope, will prompt a greater understanding about HSP.

People will figure, “‘Oh, those are the boys in the article – that’s why they’re moving like that,'” Rob says.