Research Review: Chiropractic Care and Sensorimotor Function Associated with Falls

April 30, 2018
By , DC

Study Title: Effectiveness of chiropractic care to improve sensorimotor function associated with falls risk in older people: A randomized controlled trial

Authors: Holt KR, Haavik H, Lee ACL, et al.

Publication Information: Journal of Manipulative & Physiological Therapeutics 2016; 39(4): 267–278.

Introduction

Falls are a significant cause of injury, loss of quality of life, and even death in older adults1 and make up more than 80% of injury-related hospital admissions in individuals over 65 years of age2. They are also the leading cause of death due to injury in older adults2. The risk of falls increases with lower limb muscle weakness, gait deficits, balance deficits, a recent history of falling, or in individuals over 80 years of age.3 Most falls are caused by accident and environment-related factors (31%), gait and balance disorders (17%), or dizziness and vertigo (13%).3 A growing body of scientific evidence has suggested that chiropractic care may have an influence on sensory and motor systems and therefore may impact some of the neuromuscular risk factors associated with falls.4 This study looked at the impact of usual chiropractic care on measures of sensorimotor function associated with the risk of falls in older adults over a 12-week period.

Pertinent Results

The chiropractic care group showed significant improvements in joint position sense error, sound-induced flash illusion, and choice stepping reaction time (CSRT) when compared to the control group. The chiropractic care group also showed greater improvements in the physical component of health-related quality of life between the 4- and 12-week assessments. No significant differences were seen between groups in the postural stability test; however, the inability of most participants to complete the test at baseline forced the researchers to switch to a pass/fail version of the test, which may have affected the results. No serious adverse events were reported in either group.

The CSRT test did not show significant improvements in the chiropractic group until 12 weeks. This is important, as it indicates that longer-term chiropractic care may be required to have significant effects on some aspects of sensorimotor function.

While no definite conclusions can be made, the authors suggested a number of possible mechanisms to explain the changes seen in this study:

  1. Neuroplastic processes in the central nervous system may be affected by chiropractic care due to altered afferent input as a result of improved/altered spinal function.
  2. Chiropractic care may influence pain, and in turn affect cognition, specifically attentional focus and physical function.
  3. Chiropractic care may have led to changes in muscle strength or muscle activation patterns.
  4. Placebo effect may have played a role.

Clinical Application and Conclusions

Improvements were seen in joint position sense error, CSRT, and the sound-induced flash illusion in older adults receiving 12 weeks of chiropractic care. These outcomes have been associated with risk of falling,6 which makes it possible that chiropractic care may have a role to play in fall prevention in older adults. However, the clinical significance of the changes shown is not clear and needs further research. The physical component of quality of life showed clear improvements in older adults receiving chiropractic care and no significant adverse effects were reported, showing that chiropractic care was beneficial to this group. The authors should be commended for conducting this interesting investigation on older patients, an age group that is drastically underrepresented in clinical research.

Study Methods

Twelve chiropractic practices agreed to participate and were included based on convenience and geographical location. Sixty participants were eligible and enrolled in the study (56 completed the study – 28 in each group).

Inclusion Criteria

  • Chiropractors registered with the New Zealand Chiropractic Board, with a permanent practice, and availability for new patients.
  • Adults 65 and older and living in Aukland.
  • Individuals who could understand the study information and consent process.
  • Individuals who wished to receive chiropractic care.

Exclusion Criteria

  • Individuals who were wheelchair-bound.
  • Individuals who were unable to remain standing unassisted for a minimum of 1 minute.
  • Individuals who had received spinal manipulation within the past 6 months.
  • Individuals who were considered at risk for suffering an adverse event due to chiropractic care based on their clinical history.

Originally, 30 participants were allocated to the chiropractic care group and 30 to the usual care “control” group (28 in each group finished the trial). Groups were similar at baseline demographically, medically, and for history of falls. The chiropractic care group received 12 weeks of treatment, with the specifics of their care left up to the treating chiropractor. Over the 12 weeks, the average number of visits in the chiropractic care group was 21.9 and ranged from 2 to 33. A variety of techniques were used, including high-velocity, low-amplitude, table assisted, and instrument-assisted adjustments. The usual care group continued with any usual health care they required or wished to obtain over the 12 weeks.

Outcome Measures Utilized

  1. Joint Position Sense: This was the primary outcome measure and was evaluated at the ankle. Individuals would stand with 1 foot on a swiveling platform that allowed them to rotate the platform to place their ankle into plantar/dorsiflexion or inversion/eversion, and 1 foot on a stable base. Individuals started with their ankles in neutral and were then asked to select an ankle position within their comfortable functional range of motion, then return their ankle to a neutral position, and finally reproduce or match the target position. Ankle joint position error was obtained over 20 trials (5 each for inversion, eversion, plantar flexion, and dorsiflexion, presented in random order).
  2. Choice Stepping Reaction Time (CSRT): Individuals started standing on a platform with 2 panels in front of them, 1 in front of each foot, and 1 beside each foot. Each panel could be illuminated independently, and the participant was asked to place their corresponding foot on the illuminated panel as quickly as possible. Timing was calculated over 20 trials, with 5 trials per panel presented in a random order. This can provide a broad composite measure for the neuropsychological and sensorimotor factors important for formulating and initiating compensatory steps.5
  3. Postural Stability: Individuals stood on a computerized balance platform set to create an “eyes closed on an unstable foam surface” testing condition. In this study, a large number of individuals were unable to complete the baseline assessment. As a result, a binary pass/fail assessment was used instead.
  4. Multisensory Processing: Individuals were assessed using a custom-built Macroderma Sound-Induced Flash Illusion System.6 A visual stimulus was flashed for 12 milliseconds either as a single stimulus or with a 190-millisecond stimulus onset asymmetry. In conjunction with the visual stimulus, an auditory single beep was played with the first visual stimulus or two beeps were played with the second beep presented with the second visual stimulus. Individuals were asked to report whether they saw 1 or 2 flashes. If the illusory state was successful, the individual would report 2 flashes when they were actually presented with 2 beeps and 1 flash. Forty illusory presentations randomly interspersed among 160 control presentations were used. Susceptibility to the sound-induced flash illusion seems to be related to the individual’s ability to combine multisensory input into a single percept.7 Older adults with a history of previous falls have been shown to be more susceptible to the illusion than younger individuals or older adults who had no history of falls.6
  5. Health-Related Quality of Life: The Physical Component Summary (PCS) and Mental Component Summary (MCS) scores from the SF-36 were included in this study and the summary scores were calculated using New Zealand population norms and U.S. factor coefficients.8

Outcomes were assessed at baseline, 4 weeks, and 12 weeks. Participants were also asked about injuries, hospitalizations, or perceived adverse events due to care at these times.

Study Strengths / Weaknesses

Strengths

  • Throughout the trial, all research assistants remained blinded to group allocation.
  • This is one of the few trials to use an intervention of more than 1 session. The 12-week follow-up period is more robust than the usual single intervention design, representing a more “real-world” course of clinical care.

Weaknesses

  • The use of convenience sampling may have resulted in selection bias.
  • The extra attention received by the chiropractic group could have resulted in placebo effect or performance bias.
  • The postural stability measures used in this study have been shown to have issues with sensitivity to change, responsiveness, and floor and ceiling effects. The subjects may have experienced a practice effect as well, whereby they became better at the testing procedure simply by repeating it.
  • Significant improvements were seen in a number of the outcomes between 4 and 12 weeks. It is unclear if further improvements would have been seen beyond the 12 weeks.

Dr. Thistle is a practicing chiropractor, educator, international speaker, knowledge-transfer leader, entrepreneur and medicolegal consultant. He is the founder and CEO of RRS Education, a continuing education company providing weekly research reviews, informative seminars and convenient online courses for chiropractors, physiotherapists and osteopaths around the world. He has lectured as a part-time faculty member at the Canadian Memorial Chiropractic College in the Orthopedics Department for 13 years. For questions, contact [email protected] or to learn more about RSS Education, visit www.rrseducation.com.

References

  1. American Geriatrics Society. Guideline for the prevention of falls in older persons. American Geriatrics Society, British Geriatrics Society, and American Academy of Orthopaedic Surgeons Panel on Falls Prevention. J Am Geriatr Soc 2001; 49: 664-672.
  2. Kannus P, Khan KM, Lord SR. Preventing falls among elderly people in he hospital environment. Med J Aust 2006; 184: 372-373.
  3. Rubenstein LZ, Josephson KR. The epidemiology of falls and syncope. Clin Geriatr Med 2002; 18: 141-158.
  4. Haavik H, Murphy B. The role of spinal manipulation in addressing disordered sensorimotor integration and altered motor control. J Electromyogr Kinesiol 2012; 22: 768-776.
  5. Lord SR, Fitzpatrick RC. Choice stepping reaction time: a composite measure of falls risk in older people. J Gerontol A Biol Sci Med Sci 2001; 56: M627-632.
  6. Setti A, Burke KE, Kenny RA, et al. Is inefficient multisensory processing associated with falls in older people? Exp Brain Res 2011; 209: 375-384.
  7. Statistics New Zealand. Population clock. Available at: http://www.stats.govt.nz/tools_and_services/population_clock.aspx [Accessed 18/9/2013, 2013].
  8. Frieling MA, Davis WR, Chiang G. The SF-36v2 and SF-12v2 health surveys in New Zealand: norms, scoring coefficients and cross-country comparisons. Aust N Z J Public Health 2013; 37: 24-31.