“The truth underlying it is that doing an injection is faster and results in higher reimbursements, compared to other ways of managing the same pain,” said Dr. James P. Rathmell, chairman of anesthesiology, perioperative and pain medicine at Brigham and Women’s Hospital. It was Dr. Rathmell who first brought the issue to the F.D.A. and oversaw a panel charged with recommending guidelines on safety.

“The use of injections has increased dramatically, yet the prevalence of back pain has remained relatively unchanged,” Dr. Rathmell said.

Doctors can choose among several types of epidural steroid injections. Depo-Medrol has a major share of the market. Epidural steroid injections in the cervical (neck) area and mid-back are considered the most dangerous.

They work like this: A steroid is injected into the epidural space within the spinal canal. Most of the injuries occur if the needle misses its target and directly injures nerves or places the drug into the spinal fluid or arteries, depriving the spinal cord of blood.

A review of F.D.A. records show that there were 2,442 serious problems reported from Depo-Medrol injections from 2004 through March 2018, including reports of 154 deaths. Pfizer declined to comment on the deaths, pointing to the product’s warning label: “Serious neurologic events, some resulting in death, have been reported with epidural injection of corticosteroids. Specific events reported include, but are not limited to, spinal cord infarction, paraplegia, quadriplegia, cortical blindness, and stroke.”

In West Virginia, the heart of the opioid epidemic, anesthesiologist Dr. Brian Yee said more general practice physicians are referring patients to his clinic for epidural steroid injections and other procedures, like spinal cord stimulation, than in past years.

Dr. Yee believes spinal injections are valuable if administered properly. But he worries that weekend classes aren’t sufficient training.