Forty-one-year-old Sandy Doak remembers that she was never athletic, couldn’t do sit-ups, and always had trouble finishing physical tasks. But, she says, “I never really thought I had anything wrong. I just thought I was awkward. I knew I was weaker than others. That had pretty much lasted most of my life.”
Sometimes she found herself the object of ridicule, which, while friendly, wasn’t exactly welcome. “The joke around my office when I was in my 20s was, ‘Let’s watch Sandy jump,’ and I’d jump, and my feet would not leave the floor, and we’d all laugh about it.”
A few years ago, at Doak’s office in St. Louis where she administers insurance claims for members of a carpenters’ union, a physical fitness expert visited and estimated everyone’s body fat percentage. Much to everyone’s surprise, since Doak is 5 feet tall and weighs 128 pounds, the test result said her body was 38 percent fat. There was only one way that could be the case, the fitness expert and she agreed: She had very little muscle. For Doak, it was a clue that something was really wrong.
For others, clues that something is wrong come much earlier and are harbingers of very severe problems.
By the time Jared Earlenbaugh of Reno, Texas, was 2 years old, his mother, Alexia Zuege, suspected something was wrong because he wasn’t running around like other children his age. In fact, he never ran at all and when he walked it was more of a “side-to-side waddle,” Zuege recalls. Falls caused a broken hip at age 3 and a broken collarbone at age 4.
Now a junior in high school, Jared uses a wheelchair, needs a ventilator to breathe, and can eat only through a feeding tube that bypasses his weak swallowing muscles.
Despite their different medical histories, Sandy Doak and Jared Earlenbaugh share a diagnosis, the genetic muscle disorder central core disease, or CCD. The disease takes its name from structures in the center of many muscle fibers that appear empty, or “cored.”
Varied symptoms, some commonalities
There probably is no such thing as a typical case of CCD, says Susan Iannaccone, director of pediatric neurology and the MDA Clinic at Children’s Medical Center in Dallas.
“There’s a wide variation. There’s a severe infantile and a more typical juvenile presentation, and there are adults who have it who are completely asymptomatic,” says Iannaccone, who also is a professor of neurology and pediatrics at the University of Texas Southwestern Medical Center.
“An infant with the severe form of the disease is going to be a ‘floppy’ infant and may have difficulty swallowing and breathing. These babies may require a lot of technological support early in life,” says Iannaccone. The condition of these babies frequently improves and their dependence on technology such as feeding tubes and ventilators decreases. But, Iannaccone says, there is no “100 percent certainty” of improvement.
Children who do improve generally reach their typical motor milestones, although these may be delayed, with walking achieved between 3 and 5 years of age. However, she cautions, “There’s a lot of variation on that theme.”
The juvenile presentation of CCD can also vary widely, she notes. Children may not have severe difficulties in infancy but may have some delays in meeting motor milestones and may not walk until they’re between 19 and 21 months old. (Seventeen months is considered the upper limit of the normal age range for walking, and most healthy children walk at around a year.)
Children with CCD who weren’t severely affected in infancy tend to be skinny, perhaps because they have to expend extra energy getting around and perhaps because their chewing muscles may be somewhat weakened. They may have an abnormal gait, with difficulty climbing stairs and getting up from the floor. “There may be some facial weakness and droopy eyelids,” Iannaccone says.
At the lowest end of the severity spectrum are some adults who are said to have CCD because of the appearance of their muscle biopsy samples, but who have minimal or no muscle weakness.
Despite the variations, there are some commonalities in CCD.
Muscle cramps seem to be a “common complaint across the board” for people with CCD, Iannaccone says. Also, CCD does not affect intelligence. “It’s purely a motor problem,” she notes.
Another important feature of this disease that has to be considered no matter how severe or mild the case is a susceptibility to a severe adverse reaction to general anesthesia. For more on this condition, see “CCD: Malignant Hyperthermia.”
‘Apples and oranges’
Brian Tseng, director of the pediatric neuromuscular service at Massachusetts General Hospital in Boston, where he also codirects the MDA clinic, says children are usually referred to him because they have weakness, low muscle tone or orthopedic problems, including abnormal positioning of the spine, feet or hips. The apparent bone problems, he says, are secondary to the muscle weakness, although you can’t always tell that at first glance.
Babies who come to him generally have very low muscle tone and may be seriously ill because of weak respiratory or sucking and swallowing muscles. “They’re vulnerable [to serious illness] due to respiratory and feeding issues,” he says.
But, Tseng notes, there are other children whose onset of CCD symptoms is in childhood or adolescence, and with these children, “you’re talking apples and oranges compared to the infant-onset form, even though their muscle biopsies may look very similar.”
The typical older child or adolescent who receives a CCD diagnosis may have been a somewhat floppy baby who reached his or her motor milestones, such as walking, a little bit late.
“They didn’t get medical attention until maybe their teens, when they began having trouble keeping up with their peers or couldn’t go on hikes or ride their bikes,” he says. “They have low muscle tone, mild weakness and may have muscle cramping during or after exercise.”
If a doctor carefully reviews the child’s history, Tseng says, the child “may have had some subtle problems earlier, but not enough for the parents to seek medical attention. The child was probably just a kid who compensated and settled into more sedentary activities. They’re generally all cognitively normal, and many are very bright.”
An even milder presentation of CCD can be seen in those who receive a diagnosis in adulthood, Tseng says. Some adults may come to the attention of medical professionals only after they have a child with symptoms of CCD or when they take part in a CCD research study as seemingly unaffected family members. Some may only have a spinal curvature or an abnormally high level of the muscle enzyme creatine kinase on a blood test, indicating some degree of muscle destruction is going on, but not necessarily enough for the person to notice it.
“This variation could be a fertile area to better understand the factors that enable some individuals with CCD to be less affected than others with more severe CCD,” Tseng notes.
Tseng says CCD is generally considered “nonprogressive” (doesn’t get worse), but he finds that’s true only about 90 percent of the time. “There are people who could once walk but then stop walking,” he says.
On the other hand, Tseng has seen some patients improve with time. “You have to be careful about generalizing, extrapolating from the literature whenever discussing an individual child or adult with CCD; each person is unique in amazing ways if you look carefully.”
Managing the disease
There are no specific treatments for CCD, but there are some things people can do to manage their disease and some precautions they should take.
Avoiding an episode of malignant hyperthermia during surgery is number one on the list for Iannaccone.
“The first thing I tell parents is that their child should never have any surgical procedure outside a pediatric specialty hospital, and that includes dental procedures,” says Iannaccone, who also recommends a medical ID tag that indicates the patient’s diagnosis and the contact information for his or her doctor.
Muscle cramps and pain are troublesome for many people, Iannaccone says, and they can be prevented to some extent with stretching exercises. “Cramps are usually in the weight-bearing muscles, the calves and thighs,” says Iannaccone, who recommends patients consult with a physical therapist before doing stretching at home.
Iannaccone also recommends consultations with a nutritionist to make sure patients are getting enough fluid, potassium and calcium, because a lack of any of these can contribute to cramping episodes.
For muscle pain, she recommends the anti-inflammatory medication ibuprofen, which can be purchased over the counter, and also encourages massage and warming of the muscles (such as in bathwater).
“We always write recommendations for schools that include the fact that the child should be allowed to stop and rest if they’ve having cramps or feel tired,” says Iannaccone, who says she encourages patients to listen to their bodies and respond to those messages.
“In junior high and high school, they often need extra time to get between classes, and they may need two or three sets of books so they don’t need to carry books around.”
Although she doesn’t have data to prove it, Iannaccone says she believes that, for people with CCD, “pain is not gain.”