Opioids are a tricky topic. There is no side-stepping that. While chiropractic is a profession that aims for drug-free, surgery-free care and the full expression of life without subluxations, it is a fact that opioids are a part of life for many of those under our care. Certainly, some can manage fine, while others may struggle with the side-effects these drugs bring. As America, and increasingly other countries, grapple with a crisis of opioid addition, overuse or misuse, it is critical that chiropractors understand what these drugs actually are and how they affect the body beyond the dulling of pain. As it turns out, there is a lot of complexity to this picture that we need to address.
So, opioids; what are they? When we think of opioids, we often think of strong painkillers. If we were to look in our homes, many of us would be able to find a rogue tablet or two somewhere in the back of a cupboard or box where we keep our medicines. You may not be able to pinpoint exactly when they were prescribed to you, or where the exterior box has gone, but it wouldn’t be surprising that they were there (how often have they come in handy in times of crisis!)
In the body, opioids are produced by the central nervous system and various glands around the body. They can function as hormones, released into the body’s circulation to act on distant targets, or as neuromodulators that act predominantly in the central nervous system. They are involved in many pathways including our reward and stress systems. They are also involved in pain modulation, which is what most people associate them with.
Due to their effective pain relief, opioids have been readily prescribed in response to acute and chronic pain complaints. Unfortunately, while relieving pain they are also potentially addictive in nature, due to their effect on the reward system in the brain. Beyond addiction, they have been associated with other negative side effects such as sedation, dizziness, nausea, vomiting, constipation, tolerance, and respiratory depression. These are the common ones. The more uncommon ones include delayed gastric emptying, immunologic and hormonal dysfunction, muscle rigidity or twitching [1].
A more surprising side effect is opioid-induced hyperalgesia (OIH). OIH is a state of being more sensitive to pain caused by an exposure to opioids [2]. Typically, OIH develops following chronic opioid therapy. Obviously, it does not arise in every case, however it remains a risk factor. It is important to note that OIH is different from becoming tolerant to opioids. Tolerance refers to progressively becoming less responsive to a medication and requiring a higher dosage to elicit the desired therapeutic effect. Tolerance is overcome by increasing the dosage of the medication, which often enhances other adverse side effects. OIH, as it is a form of pain sensitisation induced by the drug, typically worsens with increasing dosages. The type of pain experienced as a result of OIH may be the same as the original underlying pain or it may differ.
Let us pause a minute. I imagine you are asking yourself “Aren’t opioids meant to reduce pain, not increase it?” And yes, they are prescribed to relieve pain. And yes, there is a touch of irony in this topic.
As we know, the human body is adaptable [3]. The nervous system in particular, is continually changing and adapting to what is happening inside and outside of the body. It is this changeability that may be responsible for the enhanced perception of pain over time.
Although it sounds strange, an increase in pain sensitivity induced through the use of opioids has been repeatedly reported [2]. The existence of OIH in humans has been most thoroughly confirmed in the case of normal volunteers receiving opioids infusions. It does appear that the pain modality looked at, the way the drug is administered, and the specific opioid taken does influence the development of OIH. Still, it is a fascinating and under-reported aspect of opioid use that certainly bears a thought as the developed world battles an opioid crisis.
How does it happen?
Studies included in other reviews revealed that neuronal cell death may be a contributing factor to the development of both tolerance and OIH [4]. Other important mechanisms underlying OIH include both genetics and plastic changes in different regions of the nervous system [4]. It is thought that increased excitation of pathways related to nociceptive output to the brain lead to modulation and an increase in output [2].
While this seems like a lot to consider, there’s still more. A review published in Current Opinion in Ophthalmology included findings revealing the effects of prenatal opioid exposure on central nervous system development. Neuronal survival is affected and results in delayed maturation of white matter and decreased volume in certain brain areas. Children with prenatal opioid exposure were found to have delayed maturation of the afferent visual system, although this did recover over time [5]. Strabismus and nystagmus were also found to be more common in exposed children and seemed to persist.
Then we move on to the potentially profound endocrine effects of long-term opioid use, which has also been associated with hyperglycaemia and worsening diabetes [6]. In a cruel case of nature’s circular reasoning, hyperglycaemia decreases the anti-nociceptive properties of opioids – and as we know, nociception is all about our experience of pain [6].
Other endocrine effects can include inhibition of oxytocin, suppression of sex steroids mediated by suppression of LH and may be direct effects at the gonadal level. Significant suppressive effects on sexual behaviour. It should also be noted that men seem to have higher sensitivity to these opioid effects [6].
Where then does chiropractic enter the picture?
Chiropractic seems poised for an exciting trajectory in pain studies. Not only are we seeing case reports like the one we posted last week, where chiropractic care has been concomitant with reduction in reliance on opioids, other pain studies are showing fascinating results.
An exciting study was published in 2021 which investigated the effect of spinal manipulation on secondary hyperalgesia induced by capsaicin [7]. Pain pressure thresholds were significantly decreased in the placebo and control groups, indicative of secondary hyperalgesia, while no hyperalgesia was observed for groups receiving spinal manipulation. This research suggests that spinal manipulation may potentially prevent secondary hyperalgesia. This has significant implications for chronic pain sufferers, particularly in cases of central sensitisation.
Yet another chiropractic study showed increased cortical drive to muscles of stroke patients following chiropractic adjustment supports spinal manipulation, through the correction of vertebral subluxation, which indicated the facilitation of central neuroplastic changes [8]. This is massive, not just for stroke rehabilitation, but for the suggestion that neural plastic changes may occur in the brain of the person under chiropractic care. When that person has long term, chronic pain conditions, where the brain has certain learned responses such as hyperalgesia, this could potentially be life-changing. Further research is required to confirm this and establish the mechanisms and limitations, but it remains an exciting possibility.
What can we do?
While there is still much work to be done in researching what chiropractic care may offer, in concrete terms, when it comes to mitigating the opioid crisis, a 2020 paper published in the Chiropractic Journal of Australia had some worthy considerations [9]. The paper described how Governments, including Australia’s, have introduced plans to reduce the use and misuse of opioids using the following strategies:
- Prescription drug monitoring programmes,
- Promoting access to multidisciplinary teams; and,
- Rescheduling which medications are available over-the-counter
However, these measures are only the beginning. As we observe over in America, the crisis continues. Back pain continues to be the most common cause of pain and disability worldwide, and ineffectively managed. Although we fight against the pigeonholing of chiropractic as ‘only for back and neck pain’, this may be an important gateway into other conversations, such as immunology and neurology.
The paper suggests that for individual practitioners this may look like [9]:
- Expand on knowledge and management skills of acute and chronic pain, and be aware of current evidence-based clinical guideline recommendations.
- Be proactive in health promotion and patient education.
- Offer patients with non-cancer spinal pain evidence-based care and management strategies.
- Develop further knowledge and skills in working in multi-disciplinary settings.
- Be open to inter-disciplinary and multi-disciplinary communication.
- Support professional initiatives that promote better management of acute and chronic non-cancer pain.
- Support research through participation and/or donations.
While those under our care battle pain in the best way they can, and we offer them the best care we can — in order to help them rise out of that battle and express life more fully, it bears being well informed of the multifaceted challenges we face in respect to what is taking place in the health and lives of patients in relation to opioid use.
As chiropractors, it is essential that we become integral we become part of the answer in terms of solutions they are seeking, and equally to help them in the event that there is opioid use, excessive opioid use, or opioid misuse for the management of pain. It also demonstrates the necessity for further chiropractic research to understand how we can support patients experiencing addiction to opioid medication by intervening with a chiropractic care program.
To be part of the answer in supporting more chiropractic research, click here!
References:
- Benyamin R, Trescot AM, Datta S, Buenaventura R, Adlaka R, Sehgal N, Glaser SE, Vallejo R. Opioid complications and side effects. Pain Physician. 2008 Mar;11(2 Suppl):S105-20. PMID: 18443635.
- Lee M, Silverman S, Hansen H, Patel V, Manchikanti L. A Comprehensive Review of Opioid-Induced Hyperalgesia. Pain Physician. 2011;14:145–61.
- Angst MS, Clark JD. Opioid-induced hyperalgesia: A qualitative systematic review. Anesthesiology 2006; 104:570-587
- Mitra S. Opioid-induced hyperalgesia: Pathophysiology and clinical implications. J Opioid Manage 2008; 4:123- 130
- Lambert JE, Peeler CE. Visual and oculomotor outcomes in children with prenatal opioid exposure. Current Opinion in Ophthalmology. 2019. 30(6):449–53.
- Vuong C, Van Uum SHM, O’Dell LE, Lutfy K, Friedman TC. The Effects of Opioids and Opioid Analogs on Animal and Human Endocrine Systems. Endocrine Reviews. 2009 Nov 10 [cited 2022 Nov 9];31(1):98–132.
- Gevers-Montoro C, Provencher B, Northon S, Stedile-Lovatel JP, Ortega de Mues A, Piché M. Chiropractic Spinal Manipulation Prevents Secondary Hyperalgesia Induced by Topical Capsaicin in Healthy Individuals. Front Pain Res. 2021. 2:702429
- Muhammad Samran Navid, Imran Khan Niazi, Lelic D, Haavik H. Chiropractic Spinal Adjustment Increases the Cortical Drive to the Lower Limb Muscle in Chronic Stroke Patients. Frontiers in Neurology. 12.
- Shobbrook M, Amorin-Woods L, Parkin-Smith G. MITIGATING THE OPIOID CRISIS: AN AUSTRALIAN PERSPECTIVE ON THE ROLE OF CHIROPRACTORS (PART I): Chiropractors and Opioid Crisis I. Chiropractic Journal of Australia. 2020. 47(1):4–17.
