The Big Mystery
For a malady that’s been recognized for almost 200 years, it’s a little surprising that no one has been able to figure out what causes growing pains in children.
Doctors know enough, however, to have established that the term “growing pains” isn’t really an accurate description of the sporadically achy limbs that so many children, ages 6 to 12, complain about. But, given no clear understanding of the phenomenon, the term has stuck around for better or for worse.
“The term is a great misnomer,” says Colin Macarthur, a Canadian researcher who recently studied the problem while working at the Hospital for Sick Children in Toronto. “People have tried to use other terms, such as ‘benign leg ache in children,’ but these terms haven’t caught on.”
Children usually experience growing pains as a sensation deep in the muscles of the legs. The shins, calves, thighs and the area behind the knees are the most common sites of discomfort. The pain usually occurs in the late afternoon or evening and is sometimes intense enough to awaken children from sleep. The pains can last from a few minutes to an hour.
Once the aches begin, children typically experience them intermittently over a period of 18 to 24 months. Various studies have suggested that from 4% to 34% of all children complain of growing pains.
No one understands just what triggers the sensation, says Macarthur, who presented a physician survey on growing pains last week at the American Medical Assn. meeting for science writers in San Francisco. His study is published in the October issue of the Archives of Pediatric Adolescent Medicine.
“The cause of growing pain is unknown, but it’s definitely not growth. From the ages of 3 to 12, a child’s rate of growth is on the decline. And the sites of maximum pain are not the same as the sites of maximum growth,” he says.
Indeed, if growing pains were linked to growth, babies would be howling all the time. Children grow 7 to 10 inches in their first year of life. From ages 1 to 2, the rate slows to 4 to 5 inches. From age 2 until puberty, the average growth rate is 2 to 2 1/2 inches per year. (In puberty, growth rates accelerate again to about 3 to 5 inches a year depending on the child’s gender.)
Researchers have suggested several hypotheses to explain growing pains, Macarthur says. One theory is that fatigue causes the pain.
“The idea is that children exert themselves during the day and they have this pain at night,” he says. “The other hypotheses are poor posture and that the pains are emotional. But there is no evidence for either posture or emotions causing it.”
One study explored the idea of fatigue by having children do stretching exercises late in the day. Stretching exercises can increase blood flow to the limbs and decrease fatigue in the muscles. The children who did the stretching exercises seemed to have less pain. But, Macarthur notes, the study was not scientifically sound enough to say with certainty that stretching alleviates growing pains.
The lack of solid research on the topic means that doctors and parents are guessing as to the best approach to comfort children, he says. The syndrome can cause great anxiety in parents and even leads to repeat doctor’s office visits.
“Although the condition is common, there are very few published data on how physicians manage and treat growing pains,” Macarthur says.
In his recent study in Toronto, Macarthur surveyed 181 pediatricians, pediatric orthopedic surgeons and pediatric rheumatologists. Pediatricians were twice as likely as the specialists to order diagnostic tests, such as blood tests and imaging tests, even though there is no evidence that the tests are valuable.
“Most of the medical literature recommends that physicians order limited tests,” Macarthur says. “The rationale is to rule out serious disease and reassure parents. But the chance of a serious underlying condition is remote.”
The best strategy may be to recommend analgesics, such as acetaminophen, and massage or stretching exercises. Macarthur’s survey showed about one-third of doctors took this approach, although there is no evidence that analgesics help and only limited evidence that massage or stretching will help.
“This is a diagnosis of exclusion. If a child has unilateral pain, increasing pain, joint pain, swelling, redness or signs of a systemic illness [such as fever], then other tests might be ordered,” he says.
The older a child is, the more likely a doctor might explore other causes of the pain. But, Macarthur notes, even growing pains in a child older than 12 are unlikely to be caused by something else. “Growing pains have been known to go on into adolescence.”
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The Pain With the Wrong Name So-called growing pains, a common complaint among children 6 through 12, are usually not serious but may cause parents to worry. These are the common characteristics:
* The pain is not constant or severe.
* Pain is felt in both legs (although not necessarily at the same time).
* Pains are not just in one spot.
* The pain is not in a joint.
* There is no fever, swelling or redness.
* The child doesn’t limp.
* Pain may be alleviated by analgesics and massage.
Source: “The Portable Pediatrician’s Guide to Kids” (Harper Perennial).
