The Safety of Chiropractic Adjustments and Spinal Manipulation

David I Graber, DC, DACBSP

Chiropractic adjustments are one of the safest interventions in healthcare. Of late, there have been several reports in the popular media and on social media that question the safety of spinal manipulation in general, and chiropractic adjustments in particular. Here are some common questions that have been asked, and some evidence-based answers.

How Safe Are Chiropractic Adjustments?

Patients have more of a risk of serious injury driving a short distance to their chiropractor’s office than from any manipulation performed on them in their chiropractor’s office. While the risks are low they are not zero.

In the research literature, chiropractic adjustments are known as chiropractic manipulative treatment (CMT), spinal manipulation (SM), or spinal manual/manipulative therapy (SMT). Adverse events (AE) are undesirable outcomes as a result of the procedure. The types of AE with SMT are classified as follows:

Mild: No impact on function, and usually lasts less than 24 hours.  These include headache, dizziness, bruising, increased stiffness, increased pain, nausea, and radiating symptoms (pain, numbness, tingling).

Moderate: Some function is modified but remains intact and may require an alteration in treatment, and lasts approximately 24 hours to 1 week. Those symptoms are as listed above, plus dislocation; loss of motion; breathing difficulties; visual disturbances; facial pain, numbness, or tingling; ringing in the ears; confusion or disorientation; vomiting.

Major/Serious: Loss of function and requires medical intervention, and usually lasts greater than 1 week. All of the above, plus transient ischemic attack, stroke, fracture, loss of bowel or bladder control, and coma.

Studies of the prevalence and extent of “adverse events” (AE) are as follows:

  • Benign AE are common, affecting 23–83% of adult patients. The onset was within the first 12 hours after treatment in ~ 95% of the cases of AE. These are mostly mild-moderate and transient, usually resolving within 24 -48 hours.
  •  The most common AE were increased pain, muscle stiffness, or headache for under 24 hours (~50% of the cases).
  • Dizziness, tiredness, feeling faint/lightheaded, or tingling in the arms might also be experienced following SMT to the neck.
  • A substantial proportion of post-SMT adverse events may result from natural history variation and nonspecific effects. Studies comparing actual SMT with sham SMT found the AE rate was only slightly higher in the actual SMT group than in the sham group.
  • Serious AE are rare and are estimated at 1 in 1,000,000–250,000,000 manipulations.
  • Spinal manipulation, mobilization, exercise, or stretching have the same occurrence of adverse events. It appears that any treatment that increases movement in people with spinal pain commonly produces transient symptoms.
  • AE are more likely in women, those with pain > 1 year, and those on disability (out of work).
  • AE are reported in groups that received manual manipulation and mobilization, as well as the activator instrument.
  • One study (Achalandabaso) demonstrated that there were no significant changes in any of the blood level markers of tissue damage produced after a lower cervical and thoracic SMT.

(Rubinstein,et al.,2008; Carnes, et al., 2010; Gemmell, et al. , 2010;  Walker, et al., 2013; Carlesso, et al., 2013;  Paanalahti, et al., 2014; Achalandabaso et al., 2014; Paige, et al., 2917; Swait, et al., 2017; Nielsen,et al., 2017; Coulter, et al., 2019; Rubinstein, et al., 2019).

What is the relationship between cervical manipulation and Cervical Artery Dissection (CAD)?

Based on the best current evidence, it appears that there is no strong foundation for a causal relationship between cervical SMT and CAD. There is also no strong evidence in the literature that manual therapy provokes CAD (Wynd et al., 2008; Whedon, 2015; Church E W, et al., 2016; Cassidy, et al., 2016; Chaibi and Russell, 2019).

Vertebral artery strains obtained during cervical SMT are significantly smaller than those obtained during range of motion testing, provocative testing, and by extension, many of the activities of daily life. These strains are much smaller than failure strains. Changes in the length of the vertebral artery are small with cervical SMT (Symons B, Herzog W., 2002, 2012, 2013; Gorrell, et al. 2022 ).

There were no significant changes in blood flow or velocity in the vertebral arteries after the various head positions during both manual and instrument cervical spine manipulation (Thomas, 2013; Quesnele, et al., 2013; Kranenburg, 2019; Moser, et al., 2019; Yelverton, et al., 2020; Kocabey, 2022).

In animal studies using pigs and dogs, examiners could not tear the vertebral artery or aggravate an induced tear with manipulation procedures (Licht, et al., 1999; Wynd, et al.,2008).

Current biomechanical evidence is insufficient to establish the claim that spinal
manipulation causes CAD. The manipulative thrust is unlikely to be forceful enough to cause damage to a normal artery, and that cervical spine movements put more strain on the vertebral artery than cervical SMT. Further, nonforce cervical SMT techniques were also found associated with vertebrobasilar dissection (VAD) and stroke.  This suggests that stroke, particularly VAD, should be considered a random and unpredictable complication of any neck movement including cervical manipulation (Haldeman, et al., 2002; Biller,et al. 2014).

There are case reports demonstrating an association between patients who have visited a chiropractor and CAD. The best overall evidence is the large population studies that find no evidence of increased association of VAD after SMT in comparison to other provider visits. The research shows that there is the same risk of ischemic stroke in patients who received chiropractic care compared to primary medical care by their PCP (Cassidy, et al., 2008; Kosloff, et al., 2015; Whedon, et al., 2015).

There is some evidence to suggest that prior cervical trauma may be a cause of an adverse cerebrovascular event following cervical SMT. (Engelter, et al., 2013). Motor vehicle accidents are considered the most common cause of traumatic vertebrobasilar ischemia, and the delay of onset of symptomatology may be months to years (Beaudry, et al., 2003; Haneline, et al., 2005).

Current thinking based on the research suggests that the most plausible explanation is that these patients may present themselves to the chiropractor with a pre-existing or ongoing/underlying CAD in progress. It appears that a progression to stroke occurs as a result of the natural history of CAD. The recognition of a developing and rare CAD event is extraordinarily difficult as the symptoms of CAD in the early stages are frequently neck pain and headaches (~80%), or are sometimes asymptomatic (Murphy, 2010).

The rarity of a CAD makes it complicated to study epidemiologically. The annual incidence of internal carotid dissection (ICAD) is estimated as 2.5–3 per 100,000 (around 0.0025% of the population); for vertebral artery dissection (VAD), as 1–1.5 per 100,000 or 0.001% (Schievinck, 2001). The likelihood that a chiropractor will be made aware of an arterial dissection following cervical manipulation is estimated at 1:8.06 million office visits (0.0000125%) (Haldeman, et al., 2001).

What is the safety of spinal manipulation in patients with herniated discs?

It’s important to recognize that there is no standardized SMT procedure or protocol. With a wide variation of applications listed together as SMT, it’s difficult to distinguish which approaches are more effective or riskier than others. Still, the research has shown the safety of SMT in patients with herniated discs is favorable.

Previous estimates of the risk of spinal manipulation causing a clinically worsened disc herniation or cauda equina syndrome in a patient presenting with lumbar disc herniation (LDH) was less than 1 in 3.7 million. Current research has not found evidence of excess risk for acute LDH with early surgery associated with chiropractic compared with primary medical care. A progression to radiculopathy seems to occur mainly as part of the natural history of the disorder, independent of manipulative treatment.  (Oliphant,et al., 2004; Hincapié CA, et al., 2017; Shokri, et al., 2018).

One very small study found the following characteristics in patients who presented with LDH exacerbation following SMT: older than 50-year old; repeated episodes of lower back pain with alternating sciatica; long-standing lower back pain and sciatica over a period of 5 years; MRI-documented severe disc herniation; and bilateral symptoms and signs (Huang, et al., 2015).

There is no evidence at this time to suggest that a cervical disc herniation (CHD) is necessarily a consequence of chiropractic care or spinal manipulation. While it is doubtful that CMT causes disc herniation, it is possible that CMT may aggravate a preexisting symptomatic or asymptomatic disc herniation. Again, the evidence suggests that CHD progresses to radiculopathy or myelopathy may occur as part of the natural history of the disorder, independent of manipulative treatment (Murphy, 2006; Rubinstein, 2008).

Manipulation of the cervical spine in the presence of HNP can be considered a safe and effective part of an overall management strategy for patients with radiculopathy. Joint dysfunction at the level of the disc herniation is the target of manipulation. No manipulation at the level of disc herniation is indicated without joint dysfunction. It is recommended to avoid extension which narrows the IVF, and consider using a traction-assisted SMT (Murphy, et al., 1999, 2006,2008; Petersen, et al., 2013)

Is it safe to adjust children?

The most exhaustive exploration of the safety of pediatric chiropractic care is the report by Safer Care Victoria (SCV) titled, “Chiropractic spinal manipulation of children under 12”. The report found:

Very little evidence of patient harm from spinal manipulation in the treatment of children under 12 years.

 3 reports of serious harm were reported relative to spinal manipulation – None of these events involved chiropractors, nor did they feature techniques used by chiropractors in Australia.

 Reasons given why evidence of harm was low:

– Spinal manipulation is rarely applied by chiropractors in the treatment of children under 2 years.

– Chiropractors utilize modified force techniques such that there is little likelihood of children receiving high velocity, low amplitude thrust spinal manipulation.

(State of Victoria, Australia, Safer Care Victoria, October 2019)

How can chiropractors minimize the potential for adverse events?

There are several strategies that chiropractors can do to lessen the risk of AE occurring or reduce their severity.

  • Take a Good History:
    • Many symptoms assumed as AE are often preexisting and unreported during consultation unless asked for.
    • In older patients look for certain co-morbidities that may require more attention:
      • Chronic coagulation defect
      • Inflammatory spondylopathy
      • Osteoporosis
      • Aortic aneurysm and dissection
      • Long-term use of anticoagulant therapy
  • Take a good history of spinal trauma, especially of the cervical spine.
    • Detect the signs and symptoms suggestive of stroke, such as the, “5 Ds And 3 Ns”:  diplopia, dizziness, drop attacks, dysarthria, dysphagia, ataxia, nausea, numbness, and nystagmus.
    • Be alert for the symptoms of acute, sudden, and unfamiliar pain/headache in the ipsilateral frontal, periorbital upper neck region in a younger patient under 55. The possibility of CAD should be considered however the majority of patients with this symptom will not have CAD. This is often reported as: “The worst headache ever”, “Thunderclap”, or in frequent headache patients as “A headache unlike any other”.
  • Be aware of contraindications to SMT, such as:
    • Congenital anomalies (e.g. joint fusion).
    • Recent or unhealed fractures.
    • Certain disease processes such as primary bone tumors, metastases, osteomyelitis, and rheumatoid collagen necrosis.
    • Worsening neurological function
    • Upper motor neuron lesion
    • Spinal cord damage
    • Unremitting night pain
    • Unremitting, severe non-mechanical pain
    • Evidence of suspected cervical artery dissection
  • Adapt your clinical approach to the following precautions:
    • Hypermobility syndromes and connective tissue disorders
    • Local infections
    • Osteoporosis/Osteopenia
    • Active or history of cancer
    • Inflammatory disease
    • High fear avoidance behaviors
    • Long-term corticosteroid use
    • Cervical spine trauma
  • Perform a good physical examination prior to administering any CMT. Include a neurological exam. A good concise one is the “2-minute Neurological Exam” as outlined by Dr. Donald Murphy and can be found here:
  • Explain possible benign and transient AE to patients, especially in the first few visits. AE are most prevalent at the beginning of treatment and diminishes thereafter in frequency.
  • If the history taking indicates possible VAD, then not only is cervical SMT contraindicated, cervical spine ROM examination is also contraindicated.
  • If there is no suspicion of vascular pathology or instability from the patient’s history and ROM testing, put the patient in a sustained pre-manipulative position for a few seconds and note if there are any negative symptoms such as muscle spasm or guarding, increased pain, radicular symptoms, dizziness, etc.
  • When in doubt, err on the side of conservatism. There are fewer problems delaying giving an adjustment than rushing in to do so.
  • Use care with extreme ranges of movement, especially rotation, with HVLA techniques. Avoid over-rotation.
  • Most patients (97.6%) reported success using strategies to mitigate benign AE’s. Patients perceived that stretching, either before or after SMT, was the strategy most likely to mitigate benign AEs from occurring. This was followed by education and/or massage after SMT. (Funabashi, et al, 2020)
  • If a significant AE occurs, do not attempt to re-adjust the patient. Monitor and stabilize them and decide if a referral for medical care is indicated.  If a referral is deemed warranted, do it immediately.

Properly applied chiropractic adjustments remain a safe procedure with a highly favorable benefit-risk ratio. Making them safer can only benefit our patients to ease their pain and suffering.

For more information and CE credit on this topic, go to the webinar from NECHS, Preventing Complications of Cervical Spine Manipulation:

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