As he climbed into an Uber in May 2018 bound for a Washington emergency room, Michael Zelin remembers thinking he’d be home in a few hours, after a doctor checked out his sore arm and prescribed a painkiller.

The previous weekend, Zelin had pushed a heavy double stroller containing two of his children around a 5K racecourse near his home. A day later, the 39-year-old real estate executive headed to a South Carolina resort where he played 36 holes of golf in two days.

He assumed he’d overdone it and strained the muscles in his right forearm. But when his pain intensified, a friend, Washington hand surgeon Noah Raizman, advised him to head to an ER in case his pain signified something more serious.

“My initial thought is that it’s probably a bad muscle strain,” Raizman recalled, “or that he might be getting a little rhabdo” from overuse. Rhabdomyolysis is an uncommon and serious condition that causes muscle breakdown and requires medical attention. The disorder has a multitude of causes including injury and overexertion.

So Zelin headed to Sibley Memorial Hospital, where Raizman is on staff.

“They started running all these tests,” Zelin recalled. “Then it turned a corner and the pain got really bad.”

Tests showed no signs of rhabdomyolysis. Zelin’s white blood cell count was normal, which seemed to point away from infection. The working diagnosis was tendinitis, an inflammation of the tendon that often results from overuse. But tendinitis doesn’t usually worsen so dramatically or so quickly. And Zelin’s forearm was becoming increasingly swollen.

An MRI scan performed about 3 a.m. was “torture,” Zelin recalled. Obtaining decent images required that his arm be kept straight and that he remain motionless.

“I was sweating and crying and finally said, ‘You have to stop this,’ ” he remembered telling the technician. “I had never been in so much pain in my life.”

Shortly before 5 a.m., Zelin’s wife, Lauren, called Raizman. Zelin had received double doses of morphine, which wasn’t allaying the pain, and was disoriented.

Raizman headed to the hospital. He said he was increasingly worried that Zelin was showing signs of acute compartment syndrome. The problem, often caused by a crush injury, occurs when pressure inside muscles builds, cutting off blood flow to the affected limb.

“With compartment syndrome,” Raizman said, “time equals muscle.” In 2014, PBS science correspondent Miles O’Brien developed acute compartment syndrome after heavy camera equipment fell on his arm during a reporting trip to the Philippines. O’Brien did not realize the injury was serious and continued working. A day or so later when he sought treatment, his arm had to be amputated just above the elbow.

When he arrived in the ER, Raizman performed a compartment pressure measurement test, in which a needle is inserted into a muscle. The result erased any doubt: Zelin’s pressure measured 70 mmHg, more than double the reading that indicates acute compartment syndrome. An emergency fasciotomy would be required to relieve the pressure, decrease the swelling, and, hopefully, save his arm.

But a key question lingered unanswered: What had caused the compartment syndrome in the first place?

Solution:

The first operation, which involved making an incision that stretched from Zelin’s right palm to his elbow, went well. Raizman said he was hugely relieved to see that the muscle looked healthy. A repeat procedure was scheduled for the next day to clean out and inspect the wound, which would need to be closed.

But the surgery alone did not solve the underlying problem, which posed an even greater risk than compartment syndrome.

A few hours after the first operation, while Zelin was recovering in the intensive care unit, he developed a fever, which began to climb. An infectious-disease specialist said that Zelin had developed an infection that would require high doses of several antibiotics to treat staphylococcus and streptococcus bacteria.

A few hours after meeting with the specialist, Lauren sought out the ICU doctor to tell him something she had forgotten to mention. Several days before Zelin’s arm started to hurt, she had been diagnosed with strep throat, a bacterial infection caused by Group A strep. Could the events be related?

The following day, tests revealed that the connection seemed likely.

Zelin was suffering from necrotizing fasciitis — popularly dubbed “flesh-eating bacteria.” The fast-moving infection, which kills about 30 percent of those who develop it, is most often caused by Group A strep and, less often, staph. It can lead to septic shock, which has an even higher fatality rate. In addition to high doses of intravenous antibiotics, multiple surgeries may be necessary to remove infected tissue.

After tests showed that Zelin’s infection was caused by strep, the couple’s three children were tested. All were infected, although none showed symptoms.

Raizman said that doctors theorize that Zelin overexerted himself playing golf, which probably caused slight muscle damage to his forearm. Group A strep was probably lurking somewhere in his nose or mouth and migrated to his arm, triggering necrotizing fasciitis. The infection caused so much swelling that it led to acute compartment syndrome.

It is a very rare scenario, but one that has been reported previously. In 2008, Ohio doctors published a study of 13 cases over a 57-year-period involving men who developed acute compartment syndrome caused by strep after a nontraumatic injury. Most were previously healthy.

After a fourth operation performed by a plastic surgeon to close the wound, Zelin went home, eight days after he had arrived in the ER. A catheter called a PICC line had been implanted in his chest to deliver the IV antibiotics he would need for the next six weeks.

Two months later, after physical therapy, Zelin had regained nearly full use of his arm and hand.

The psychological aftereffects have taken longer to resolve.

“I replayed it many times,” Lauren said. Raizman later told the couple that a delay of four to six hours would probably have cost Zelin his arm.

“This was the luckiest we could have gotten,” Raizman added. “I’ve never gotten to a case of necrotizing fasciitis so early and seen so little damage.

Raizman warned that any pain that seems out of proportion to an injury or that is worsening rapidly should prompt an immediate visit to an ER, not an urgent care center. “This is exactly what you should be going to an ER for,” he said.