Lisa Perrin
Your eight-year-old can't sleep because his legs ache. Your friend's five-year-old daughter wakes up crying in the middle of the night with the same complaint. After mom or dad massages their legs, the children are able to fall asleep and awake in the morning feeling fine. By adolescence, the sporadic night pains go away completely.
Commonly called "growing pains," this phenomenon—both very real and a medical mystery—has nothing to do with growing, says Barbara Ostrov, division chief of pediatrics and rheumatology at Penn State's Milton S. Hershey Medical Center.
If rapid growth is not the culprit, what is happening in those little legs that makes kids so uncomfortable?
"Actually, over the years nobody has really been able to understand what causes these symptoms and why it hits this age group so specifically," says Ostrov. "We do know that growth itself does not cause pain," she adds.
Doctors refer to this medical phenomenon as "non-specific limb pains of childhood" and estimate that 20 percent of children aged 2 to 12 report mild to severe pain in their legs at night. There is no swelling, redness or inflammation, all signs of something serious. There are no symptoms in the morning. "When different patients come in, you'll get the same histories," says Ostrov. "One child will be from Reading, another will be from York or Altoona and the history is exactly the same. It's a very clear, typical presentation. In most cases, the kid is fine in a half hour and wakes up in the morning as if nothing happened. And the pains always go away."
Children who experience these pains usually complain of feeling them in both legs anywhere from once a week to once per month. When children have limb pain three to four times a week, doctors typically order X-rays, blood tests or an MRI to rule out infections, inflammations, tumors, or other pathology. Says Ostrov, if those tests come back normal, she may suggest acetaminophen or ibuprofen before bed to help kids suffering from the most severe and frequent bouts of night leg pain.
Some studies indicate the causes of such pains share similarities with shin splints, pain along the shins that can be a sign of overused muscles, stress fractures of the lower leg bones, or muscle and tendon stress caused by flat feet. Notes Ostrov, this connection is consistent with parents' observation that when their kids have an especially physically active day, their night leg pains can be worse.
Another study, conducted at the Cleveland Clinic in 2004, measured the pain threshold of children who suffer from these pains and found they have an increased sensitivity to pain compared to a control group of the same age and gender.
Whatever their underlying cause, most of the time children with these types of limb pains have nothing to worry about, says Ostrov. The danger is if a parent or pediatrician doesn't carefully rule out more serious conditions if the child has persistent pain or atypical symptoms.
"Sometimes people attribute symptoms to 'growing pains' when it isn't that at all, which I think is potentially hazardous to the child's health," says Ostrov. While night pain in both legs with no other symptoms and no problems during the day is likely harmless, if children have pain in just one leg, pain present during the day, or other symptoms such as inflammation (along with skin heat or color change), this might indicate something more serious, says Ostrov. "Those to me are red flags that something else is going on."
Barbara Ostrov, M.D., is professor of pediatrics and medicine and division chief of pediatrics and rheumatology at the Penn State Milton S. Hershey Medical Center. Her email is bostrov@psu.edu.