As research mounts up, it is becoming increasingly clear that neck pain has impacts far beyond pain and stiffness. A recent piece of research, partially funded by the Australian Spinal Research Foundation, has become the first to reveal that people with subclinical neck pain have slower visual and multisensory response times, and the differences caused by subclinical neck pain don’t improve on their own.
The research emerging up until this point has offered clear indications that neck pain has impacts on multiple areas of brain function and proprioception. Among the already-available research is work indicating:
- Proprioceptive differences in upper limbs [1]
- Negative impacts on cortical and cerebellar motor processing [2]
- Decreased mental response times for complex rotation tasks [3]
This latest study adds to that body of evidence, this time focusing on visual and auditory cues. It took place in Canada using volunteers recruited from a university student population, and saw 25 volunteers put through a 2-alternative forced-choice discrimination task. They were reacting to visual, auditory and combined audio-visual cues at a baseline measurement session and again four weeks later. The study design, and tools used to measure responses, ensured that there was minimal lag in logging response times, and that left-handed and ambidextrous participants were able to participate.
Researchers were working with the hypothesis that “individuals with SCNP [subclinical neck pain] would possess slower response times for both unisensory and multisensory conditions because of the ongoing effects of unreliable proprioceptive feedback from the neck [4].”
While the auditory stimulus data didn’t reveal a notable difference, there was a statistically significant difference in response times for visual and multisensory stimuli. Researchers said:
“These differences are not simply because of slower movement times in general, because previous studies of people with SCNP reported no difference in simple response times in this population but found that the SCNP group had slower response times in more complex tasks (mental rotation) [4].”
Response times for the visual stimulus in this study were slower by 48 ms baseline and 37 ms at week 4, when compared with the control group. This was found to be statistically significant, as was the multisensory stimulus response time that was slower for the SCNP group by an average of 52 ms at baseline and 47 ms at week 4.
For the purpose of this study, participants were required to not seek treatment until after the 4-week check in. This allowed researchers to see if the symptoms improved on their own. They did not.
Additionally, a recent study indicated an increased reliance on visual input in people with chronic neck pain [5]. This, combined with findings of impaired mental rotation abilities in SCNP patients [3], lead researchers to state:
“If patients with neck pain have an increased reliance on vision and their visual and multisensory processing response times are impaired, as indicated in the present study, it is problematic. Our study identified worse visual and multisensory reaction times in SCNP vs asymptomatic young adults, which was not compensated for by increased multisensory gain between the 2 groups, for both the standard t test and CDF analysis. The lack of change over 4 weeks suggests that left untreated, even subclinical neck pain can affect multisensory processing [4].”
This study has clear implications for chiropractic, which has not struggled to assert its role in assisting neck and back pain sufferers. As we saw in Kelly Holts falls risk study, there are also clear indications that chiropractic care may improve sensorimotor function and multisensory integration in older adults [6]. These studies are not without their limitations, and as the body of evidence continues to grow so to will the funds for research and the larger, more technical and costly studies will be able to be funded.
We can now clearly see that the ability of the brain to integrate sensory inputs is affected in those with recurrent neck pain, and that altered sensory input from the neck appears to interfere with the ability to integrate inputs from other sensory stimuli.
All this evidence points to something remarkably simple – Don’t wait for neck pain to improve on its own. Get to your chiropractor! That simple act may influence a lot more than just your neck!
References
[1] Haavik H, and Murphy B (2011), “Subclinical Neck Pain and the Effects of Cervical Manipulation on Elbow Joint Position Sense,” JMPT Vol 34, Iss 2, Feb 2011, pp. 88-97, https://doi.org/10.1016/j.jmpt.2010.12.009
[2] Daligadu J, Haavik H, Yielder P, Baarbe J, and Murphy B (2013), “Alterations in Cortical and Cerebellar Motor Processing in Subclinical Neck Pain Patients Following Spinal Manipulation,” JMPT Vol 36, Iss 8, October 2013 pp. 527-537, https://doi.org/10.1016/j.jmpt.2013.08.003
[3] Baarbe J, Holmes M, Murphy H, Haavik H, Murphy B (2016), “Influence of Subclinical Neck Pain on the Ability to Perform a Mental Rotation Task: A 4-week Longitudinal Study with a Healthy Control Group Comparison,” JMPT Vol. 39, Iss. 1, Jan 2016 pp. 23-30, https://doi.org/10.1016/j.jmpt.2015.12.002
[4] Farid B, Yielder P, Holmes M, Haavik H, and Murphy B (2018), “Association of Subclinical Neck Pain With Altered Multisensory Integration at Baseline and 4-Week Follow-up Relative to Asymptomatic Controls,” JMPT Vol. 41 Number 2. Feb 2018, pp. 81-91
[5] Harvie DS, Broecker M, Smith RT, Meulders A, Madden VJ, Moseley GL. Bogus visual feedback alters onset of movement-evoked pain in people with neck pain. Psychol Sci. 2015;26(4):385-392.
[6] Holt KR, Haavik H, Lee ACL, Murphy B, Elley CR. Effectiveness of chiropractic care to improve sensorimotor function associated with falls risk in older people: a randomized controlled trial. J Manipulative Physiol Ther. 2016;39(4):267-278.
