At age 7, Marley Robinson is already thinking about a future when children like her won't have to consider multiple surgeries a routine part of their growing up.

“I'm going to be an inventor when I grow up,” she said, sitting erect in her power wheelchair in the kitchen of her Mystic home. “I want to invent rods that grow with you.”

Marley is a bright, sociable little girl who likes computer games, reading, the Red Sox, stuffed animals, being part of a trio of friends dubbed “The Three Stooges,” and watching her big brother play Little League. Last week, she underwent — for the sixth time — an unusual type of surgery. Several more await her over the next few years. Though the surgical route can be arduous, the positives clearly outweigh the negatives in giving Marley the kind of life her parents, Gabrielle and Karl, want for her, given her circumstances.

Marley has spinal muscular atrophy, a genetic disorder that causes muscle weakness throughout the body, but especially in the muscles that support the body's core, including the back, hips and shoulders.

Marley's muscle and motor development slowed considerably after she sat up at 6 months old, her parents recalled. She never walked. She started using a wheelchair at 18 months.

Doctors initially assured them she was just progressing more gradually than other children and would catch up. But ultimately, on the advice of a child-development specialist who had been visiting Marley through the state's Birth to Three program, the Robinsons insisted Marley have a blood test. The test confirmed she had type 2 spinal muscular atrophy.

Called SMA, the condition affects one in 6,000 babies and is one of the most common genetic disorders, according to the SMA Foundation. In people with SMA, a certain gene is missing or mutated. The gene is responsible for producing a protein essential for the healthy function of motor neuron cells in the spinal cord — the cells that send signals to muscles throughout the body.

Without the protein, nerve cells atrophy, and muscles become weak. Without treatment, the condition leads to scoliosis and other spinal cord deformities. Breathing problems and susceptibility to pneumonia are also common, because of weakness of lung muscles. About 25,000 people in this country have SMA.

There is no cure, but one important avenue of research is focusing on using human stem cells to make the motor neuron protein and injecting this into patients with SMA.

While scientists search for a cure, families like the Robinsons are left to choose between two main approaches to treatment. The one the Robinsons rejected would have put Marley in a body cast. Instead, they opted for the surgical insertion of growth rods, even with the risks of repeated surgeries, because they believed her quality of life would be better.

Though the surgical path is difficult, the Robinsons have become increasingly convinced they chose the better of the two options, particularly when they've talked to other SMA families and learned about SMA patients who've been using a body cast for decades. With her upright, active posture and the lack of cast apparatus confining her, it's been easier for Marley to be part of her peer group and maneuver herself around in her wheelchair to keep up with her classmates.

“We made the right decision,” said Mrs. Robinson. “I'm hoping that (hearing Marley's story) will help others who are considering the surgery.”

Dr. John Grayhock, pediatric orthopedic surgeon at Children's Memorial Hospital in Chicago and a member of the medical advisory board of the Families of SMA, said a body cast is still typically the way SMA patients are initially treated but, often, the cast fails to correct the curvature sufficiently, and patients have the growth rods implanted.

Wearing a body cast, also called bracing, has some significant problems, he said. The Robinsons saw some of these firsthand in the short time Marley wore one, before the decision to implant the rods was made, but when she still needed support. Cast wearers can also have frequent skin problems, and their lungs and other internal organs aren't in as good alignment compared with the rods.

“It's hot in the summer, and it's bulky,” said her father. “With the rods, she has more and better movement.”

The rod technology, Grayhock said, has been improved significantly over the last 10 years, so that there are more variations available to fit a specific patient's needs. They're called growth rods, or a growing rod system, because they telescope out as the patient grows, but each expansion must be done by the surgeon.

“Usually,” he said, “it's used in young kids when the curvature of the spine is more progressed. It maintains some flexibility of the spine.”

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“The rods are acting as an internal brace,” explained Dr. Brian Smith, chief of pediatric orthopedics at Yale/New Haven Hospital, who has implanted growing rod systems in about 10 other children around the state who have the same condition as Marley.

At 10 or 11, the age when girls have completed most of their upper body growth, Smith said, Marley will have what he hopes will be her final back surgery. He will fuse the vertebrae in her spine to keep her in an upright position, possibly leaving the growth rods in place.

Smith, noting that Marley must do lung exercises regularly, said, “We're trying to gracefully get her to the stage when we can do the fusion, because while the surgery has gone well, every time there are risks.”

In addition to the risk of infection that goes with all types of surgery, the procedure also poses special challenges for Marley because the required anesthesia can be difficult for someone with compromised lungs.

“The scariest part of the surgery is getting everything out of her lungs,” her father said.

In the five days she spent at Yale-New Haven after the surgery, she had respiratory therapy several times a day along with regular physical therapy sessions, and one night her sleep was interrupted by breathing problems.

But, thanks to her good attitude and her parents' dedication to keeping her life as normal as possible, Smith said, she's adapted well to the challenges. Though she'll always have to use her wheelchair, he said, he expects that one day she'll drive a car adapted for the handicapped and go to college.

“In a way, this is a great time for her to be living, with all of the technology that enables her to live a normal life,” he said, as he waited in the hall outside her hospital room Monday morning, while technicians took an X-ray of her lungs. “In her peer group, she's just a normal kid to them.”

After the X-ray, Marley sat up in bed looking through some get-well cards from her classmates at Northeast Academy in Groton, where she is a second-grader. She showed some visitors a construction paper booklet of photographs of her classmates made by the classroom aide. Nestled in bed with her was Frank, a stuffed cockatoo; Katie, a stuffed kitten; a stuffed dog lent to her by her 10-year-old brother, Cooper; and a well-loved blanket that has been with her since she was a toddler.

Her mother, Gabrielle, said that each surgery is a little harder than the last, because as she grows, Marley becomes more aware of what's involved.

“It's fatiguing, the buildup to it,” her mother said. “She gets nervous. But overall, she has an unbelievable attitude. She's so upbeat.”

Marley said she tries to take the realities of her life in stride and looks forward to being able to rejoin her friends at school, zipping around the playground in her wheelchair.

“I just try to think that it's not going to be too bad, once I'm asleep,” she said before the surgery.

A couple of days after the procedure last week, her mother said, after nurses were able to remove the four intravenous tubes in her body, Marley was comfortable enough to start speaking again.

“She started chatting and laughing,” her mother said. “We said, 'Marley's back.' ”

Go to Slideshows on theday.com for more photos of Marley.

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