"He's acting like an old man," my patient's mother said as she locked eyes with her previously healthy 3-year-old.  "Over the past three weeks, he's been walking more slowly and is refusing to eat his meals sitting down. He wants to eat standing up," she told me.

But lately, she said, things had become even worse.

"Now he just wants to be picked up and is refusing to walk," she continued, "but he's getting too big for me to do that."

I asked about fevers, trauma, travel, and appetite. No problems to report.

"We live with my father, whom he adores, and I think he's mimicking some of his mannerisms," the mom disclosed.  Without a fever or history of trauma, I had to rely on a thorough physical exam to try to piece together this unusual presentation.

As I lifted him onto the examining table, he winced a little as if I were hurting him. I sat him on the edge of the table to listen to his heart. But right away, he lay down on his back and wouldn't sit up. As a pediatrician for almost two decades, I learned long ago to get a physical exam done any way I can. So I tilted my body sideways to look in his ears and mouth, and then was able to complete the rest of the exam, which was completely normal. As I lifted him down from the exam table to stand on the floor, he slowly shuffled over to his mother, just like an old man.

I had an uncommon diagnosis in mind, but would have to order an X-ray and some blood work to confirm.

Solution:

In 1974, anthropologists discovered a nearly complete skeleton that predated Neanderthals and Homo erectus named Lucy. Lucy lived more than three million years ago and her remains helped scientists establish that humans became bipeds, that is, walked upright, much earlier than previously thought. Walking allowed humans to use their hands for more than just climbing. As our brains became larger, inventions such as tools, weapons, and Teslas could be made to advance our species.

With gravity and time, many adults get back pain and can't walk as fast as they did in their youth. But to see this in a 3-year-old? Something wasn't right.

This young patient's blood work showed his sedimentation rate (a measure of inflammation in the body) was six times more than normal, and his white blood cell count was elevated, a common sign of infection. His X-ray showed that the intervertebral disc between his fourth and fifth lumbar vertebrae was narrowed. Diagnosis: discitis.

Discitis, or inflammation of the intervertebral discs, occurs in 1 out of 100,000 children. It is found in younger children, it is thought, because they still have blood supply to this area, something that disappears by the time kids are old enough to go to school. Usually bacteria, such as Staphylococcus aureus, seed the blood supply and infect the disc, causing inflammation and pain when walking, sitting, or any activity that irritates this area. The average age when this condition occurs is 2½ years, and symptoms go on for an average of three weeks before a diagnosis is made. The most common symptom: refusal to walk.

This child was admitted to the hospital for two weeks of intravenous and anti-inflammatory medications. Within a few weeks, he was walking more like a preschooler and less like his beloved grandpa.

Daniel R. Taylor, D.O., is an associate professor at Drexel University College of Medicine and director of community pediatrics and child advocacy at St. Christopher's Hospital for Children.