Epidural Injections: The Weakness in My Bones

I Gave Epidural Injections a Shot

I got my first epidural injection about five months into my chronic sciatica saga. Nothing I’d tried up to that point had been particularly effective, but the physician who referred me to the clinic gave me new cause for optimism. In his experience, he said, most patients would see some improvement after a course of three injections. Perhaps I wouldn’t be completely symptom-free, but he was sure the shots would bring my suffering down to a tolerable level.

I hit it off instantly with the doctor who gave me my injections. He was lively and quirky, and I remember thinking that under other circumstances, I would love to hang out with him after work. He brandished medical models of the spine, showing me where my sciatic nerve exited and how he’d approach the nerve. He told me about the doctor who had used himself as a guinea pig to determine which positions led to pressure on the sciatic nerve.

It’s hard to make friendly conversation while laying face-down on a table, with your pants pulled down on your butt, but I tried anyway. I admired the souped-up X-ray machine the doctor used to guide his needle. He smiled at that. He thought it was pretty cool himself.

I wanted the shot to fix me, or at least help me. I wanted it for the doctor’s sake, if not for my own. But alas, if the injection did anything, it made my symptoms worse. I walked around for the next two weeks feeling like my spine was a poorly constructed Jenga tower. There was an instability I had never felt before. It was as if one wrong move might cause my spine to fly to pieces, and I would come toppling down.

Over roughly the next year and a half, I would get eleven injections. They were a mixed bag. I felt as if with each shot, I was trading in my hand of symptoms for a fresh set. Once, I started getting regular cramps in my pinky toe. After another injection, I couldn’t walk for more than a few steps without getting massive cramps, but my stamina was more or less restored by the next shot. I only noticed a significant improvement once, and it was wiped away in the next round of injections.

It seemed like the doctor was nearly as frustrated as I was. When I would report, again, that the latest shot hadn’t work, he would try something different. He would approach the nerve from a different direction or change the placement of the next shot. But eventually, he ran out of things to try, and I focused on other treatment options.

At the time, I thought the injections were frustratingly ineffective, but I never considered them harmful. I’m sure this doctor did review the risks with me, but I brushed them off. I was willing to take on any fresh new hell if it meant getting rid of my sciatica.

It wasn’t until two years later, in September 2019, that I realized I was not a good candidate for a corticosteroid injection, and they may have done more damage than I realized.

Two for Three on the Female Triad

In September 2019, I started looking into an unrelated (I thought) health problem. I had been off birth control for nearly a year, and hadn’t had a single period. Come to think of it, I hadn’t had a single natural period in the past eight years, though I had been on birth control for much of the time.

As part of the workup, my doctor ordered a DXA scan to evaluate my bone density. I wasn’t expecting any problems – I took my calcium supplements, exercised, and lifted weights. I thought I was taking good care of my bones, and I expected a perfect scan.

When I got the radiologist’s report back, the bottom fell out of my stomach. It was right there, spelled out plainly in the two-sentence summary.

IMPRESSION: Low bone mineral density for chronological age, lowest Z-score is -2.2 in the L1-L4 AP spine, medical evaluation for secondary causes of low bone mineral density may be appropriate.

I had osteopenia.

And the truly scary thing was that the bone mineral density of my lumbar spine was significantly worse than the other areas quantified in the report. I was suddenly terrified that I was heading for a spinal fracture. As if my back wasn’t messed up enough!

The doctor who prescribed the DXA scan had also prescribed some blood and hormone tests, and the results of these removed all doubt – I had hypothalamic amenorrhea (HA).

Hypothalamic amenorrhea doesn’t seem to be a widely known condition, maybe because no one wants to spell it. But it’s basically an endocrine issue in which the hormonal signal to start the menstrual cycle never happens. “Hypothalamic” refers to the hypothalamus, a region of the brain that (among its other duties) releases hormones. And “amenorrhea” is just a fancy way of saying, “no periods.”

The cascade of hormonal changes involved are about as complicated as the name would suggest., and I’d be lying if I said I understood all the details. But basically, there are three underlying lifestyle issues. Sometimes one condition alone is enough to cause HA, and sometimes it’s a combination.*

1. Not eating enough
2. Excessive exercise
3. Psychological stress

*There are other medical conditions which can predispose a woman to HA, but this is a reasonably good in-a-nutshell explanation.

I was a bit surprised, honestly. HA is usually associated with athletes in sports where there is a lot of pressure to be thin (dancers, long-distance runners, gymnasts, and so forth). I like to exercise, but I have never been an athlete, and I considered myself unusually good at dealing with stress.

My BMI at the time was 16.7, which put me solidly in the underweight category, but my weight was stable and I had never had an eating disorder. I thought my diet and exercise habits were, if anything, excessively healthy. It was a shock to hear that perhaps my “healthy” habits had been leeching minerals from my bones this whole time.

Connecting the Dots: Epidural Injections, Hypothalamic Amenorrhea, and Low Bone Density

Around this time, I read Crooked: Outwitting the Back Pain Industry and Getting on the Road to Recovery for the first time. A few paragraphs in the “Needle Jockeys” chapter gave me my first glimmer of enlightenment.

Systemic glucocorticoid treatment in tablet form has long been recognized as a factor in bone mass loss, as well as a harbinger of increased risk of bone fracture. Although the FDA does not recommend oral steroids (methyl prednisolone, prednisolone, and prednisone) for the treatment of any type of low back pain or sciatica, epidural steroid injections, which involve the same class of medication, have conventionally escaped scrutiny.

The author then went on to recount a study which showed that in women over 65, each epidural steroid injection increased the risk of a vertebral compression fracture by 21%.

I started to wonder if bone density loss that was so pronounced in my lumbar spine might be related to the epidural injections I had received. So I went poking around on Google Scholar.

I found that the relationship between oral corticosteroids and bone density loss has indeed been well studied and is well established. These drugs interfere with the process by which existing bone is broken down and new bone is produced. The end result is that existing bone is broken down faster than it can be replaced, which leads to a loss in bone density.

I also learned that oral corticosteroids can mess with the hormone activity of the hypothalamic-pituitary-adrenal (HPA) axis – the same system that is disrupted in HA – and cause abnormal menstruation even in healthy women.

There is some evidence to suggest that when the same drugs are injected, they have a similar effect on bone density. However, the existing studies on corticosteroid injections have mainly focused on postmenopausal women, so any conclusions are highly qualified.

If you’re interested, this editorial accompanying a recent review did a good job spelling out the current evidence, and the pitfalls of jumping to conclusions.

As for the HPA axis connection, clinicians seemed to develop a greater awareness of the link between corticosteroid injections and menstrual irregularities even before the research was there to support it. Subsequent studies supported the connection, and these days it seems to be generally acknowledged.

Where Does That Leave Me?

So did the epidural injections accelerate the bone density loss in my lumbar spine? I couldn’t prove it in a court of law. Since I didn’t have a DXA scan until seven months after my last injection, I don’t know for sure if the injections were correlated with bone loss. Even if I could prove causation, I don’t think any doctor knows for sure what effect that will have on my fracture risk thirty years from now.

Still, I find the evidence convincing enough to think that I did not escape unscathed. We may not have a lot of evidence about how injections affect people with low bone density who are not older women, but given the risks when the same drugs are administered in other ways, I can’t imagine the shots helped me any.

My takeaway here is that even commonly prescribed drugs and routine procedures may have long-term risks that are not at the top of doctors’ or patients’ minds at the time they’re administered. I doubt I’ll see the doctor who injected me again in the next few years, let alone in the distant future when the bill for my bone loss comes due. If a doctor never sees the long-term effect, why would he think to worry about it?

And if anyone had good cause to assume bone loss was a concern, it was me, not my doctor. After all, no one knows my body better than I do. That may be a cliche, but it’s also true. My inner skeptic just got a little stronger.