Elusive growing pains Health: Though recognized for 200 years, still nobody knows what causes this affliction among the young.

November 19, 1996|By Shari Roan | Shari Roan,LOS ANGELES TIMES

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 percent to 34 percent 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 recently at the American Medical Association meeting for science writers in San Francisco. His study was published in last month's 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 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.

"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, although there is no evidence that analgesics help and only limited evidence that massage or stretching will help.

Pub Date: 11/19/96

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