The Sorcerer’s Apprentice
Few movies lodged themselves in my childhood brain the way Fantasia did. A psychedelic 1940s Disney animation set to a thundering score played by a maniacal Philadelphia Orchestra, it broke artistic ground as quickly as it laid it.
The scene that branded itself on my memory, though, was that of the Sorcerer’s Apprentice. Set to freshly composed symphonic torment, it follows Mickey Mouse playing understudy to a great magician (based on a 1797 ballad by Goethe, “Der Zauberlehrling”), and, with Mickey being too lazy, or perhaps too enterprising, to fetch the buckets of water that were part of his job description, he steals his master’s wizardly hat and conjures a spell to have a mop do the work for him. In a (mildly, now that I re-watch it for research) terrifying escalation, however, Mickey hacks at the mop with an axe to halt its autonomous and uncontrolled toil, against a seizure of blood-red backdrop, and with shadows billowing up like nightmares on the walls behind them, the mop replicates like a clone army, trampling over our poor mouse as he succumbs to the purgatory of his decision.
The reason I relate this disturbing memory to you is to try and illustrate what tends to happen when a simple question is posed in Emergency Medicine. Today’s columned cascade of questions arose during a discussion about the possibility of using intravenous dexamethasone to treat acute back pain. The question, ‘Is dexamethasone effective in treating acute back pain?’ then splintered into a thousand further questions. Let us watch them reproduce, without the soaring soundtrack.
Is parenteral dexamethasone effective in the treatment of acute back pain?
The totality of current evidence says probably no. There are a few small-scale studies desperately trying to prove the affirmative, but they are, as is so often the case, meager in numbers, negative on primary outcomes, single-centred, and non-replicable.
It is at this point, however, that the questions begin to split off.
How might dexamethasone work for back pain in the first place?
There’s got to be an inflammatory component, right? So surely there’s some biological plausibility in here.
And back up. We know it works when it’s injected directly around irritated and compressed nerve roots.
Although if we’re expecting to see some relief in the Emergency Department, that presupposes dexamethasone works pretty quickly. Do we really understand what we’re doing by giving dexamethasone?
It gets a little furry here. Although we were all taught steroids need to be transported into the nucleus to exert its conformational change and effect, we also know that steroids work in at least three ways: slow, quick and hey that’s weird.
Do we even know what we are trying to treat when we are providing analgesic options in acute lower back pain in the ED?
It is likely that the patients we see in ED with acute (not chronic) back pain have a cornucopia of pathological mechanisms resulting in the pain we are assessing. The most common likely mechanism is the sudden wrenching of the facet joints. Facet joints have a rich neural network around them causing, among many things, severe muscle spasm. But they also have a relatively poor blood supply, delivering not much of anything to them. There are other paths to pain, though. Herniated discs expose a hugely inflammatory core. Discs impinge upon nerve roots, causing neuropathic pain. Hitting the inflammatory pathways will only modulate some of these, and without the benefit of advanced imaging in the ED (appropriately) we will not sure how much of each of these are contributory.
But hang on, many of these acute injury patho-physiologies must have an inflammatory component somewhere, so isn’t the balance tipping in favour of trying steroids?
Horses need to be held here. Much of this is about the ‘acute injury’. We don’t give steroids for acute ligamentous sprains. We (definitely) don’t give steroids in acute brain injury. The risk-benefit profile must be way in the negative here. The side-effects/risks of steroids are well-known.
Counter to that, though, dexamethasone is superb at dampening down the inflammatory aspect of a mind-boggingly vast number of diseases. Perhaps inflammation is at the core of ALL of our ills?
Man, this could be true. Sore throats, swollen throats, viral neuropathies, bronchospasm, cerebral oedema, spinal cord compression, oxygen requiring COVID, arthritidies, uveitidies, colitidies, altitude sickness. All of them exquisitely responsive to dexamethasone. We give it when there’s too much thyroxine, we give it when there’s too little thyroxine. We give it in skin problems, eye problems, allergic problems, blood problems …
It is at this point that the questions begin marching over us, unyielding, heedless of the existential pain they might be inflicting.
What is it with the body that there are so many conditions that require exogenous steroids for treatment?
Is this a design fault?
What is the purpose of pain?
What is the purpose of life?
And you see where this is going. Nowhere good. Like Mickey Mouse, who opened a Pandora’s Box, to thoroughly mix story and myth, a seemingly benign question has become something horrifying.
So let us return to the original question. Parenteral dexamethasone for acute back pain in ED. Probably not justified. Perhaps the best treatment for back pain is avoidance – such as finding an alternative to back pain inducing activities, such as carting buckets of water.