Clinical Neurophysiology, February 2007, Vol. 118, No. 2, pp. 391-402.
Haavik-Taylor H, Murphy B; Human Neurophysiology and Rehabilitation Laboratory, Department of Sport and Exercise Science, Tamaki Campus, University of Auckland, New Zealand.
Cervical spine manipulation alters sensorimotor integration: A somatosensory evoked potential study
This article notes the following concepts:
1. “Spinal manipulation is a commonly used conservative treatment for neck, back, and pelvic pain.”
2. “The effectiveness of spinal manipulation in the treatment of acute and chronic low back and neck pain has been well established by outcome-based research.”
3. Spinal dysfunction will alter afferent input to the central nervous system.
4. Altered afferent input to the central nervous system leads to plastic changes in the central nervous system.
5. “Neural plastic changes take place both following increased and decreased afferent input.”
6. Both painful and painless joint dysfunction will inhibit surrounding muscles.
7. Joint dysfunction causes afferent driven increases in neural excitability (facilitation) to muscles that can persist even after the initiating afferent abnormality is corrected. (This suggests that a muscle afferent problem can persist even after the joint component of the dysfunction is corrected. The chronic component of the joint dysfunction may be plastic changes that cause long-term alteration of muscle afferentation.) This article clearly supports that the joint component, the muscle component, and the neurological component of a joint dysfunction complex is influenced by traditional joint-cavitation spinal adjusting.
8. The altered neural processing that occurs as a consequence of joint dysfunction provides a “rationale for the effects of spinal manipulation on neural processing that have been described in the literature.”
9. Spinal dysfunction alters the “balance of afferent input to the central nervous system” and this altered afferent input may lead to “maladaptive neural plastic changes in the central nervous system,” and “spinal manipulation can effect this.”
10. The clinical evidence for joint dysfunction that requires manipulation includes:
A. Tenderness on joint palpation.
B. Restricted intersegmental range of motion.
C. Palpable asymmetry of intervertebral muscle tension
D. Abnormal or blocked joint play
E. Sensorimotor changes in the upper extremity.
11. High velocity, low amplitude thrust spinal manipulation with the head held in lateral flexion, with slight rotation and slight extension “is a standard manipulative technique used by manipulative physicians, physiotherapists and chiropractors.” (This is important because this is the type of spinal adjusting that many chiropractors perform on cervical vertebrae. This article indicates such adjustments are “standard.”)
12. High-velocity manipulation causes significant cortical SEP amplitude attenuation in at least the frontal and parietal cortexes.
13. Passive head movements do not cause changes in cortical firing.
14. “A single session of spinal manipulation of dysfunctional joints resulted in attenuated cortical (parietal and frontal) evoked responses.” These changes “most likely reflect central changes.”
15. The cortical (brain) function of different individuals responded differently to spinal adjusting. (This indicates that variables other than the adjustment/manipulation itself can influence the cortical responses in a given individual)
16. The significantly decreased somatosensory cortical SEP occurred in all post-manipulation measurements, indicating “enhanced active inhibition” because the “cervical manipulations could have altered the afferent information originating from the cervical spine (from joints, muscles, etc.)”
17. “The passive head movement SEP experiment demonstrated that no significant changes occurred following a simple movement of the subject’s head. Our results are therefore not simply due to altered input from vestibular, muscle or cutaneous afferents as a result of the chiropractor’s touch or due to the actual movement of the subject’s head. This therefore suggests that the results in this study are specific to the delivery of the high-velocity, low-amplitude adjustment/manipulation to dysfunctional joints.”
18. “Displacement of vertebrae is signaled to the central nervous system by afferent nerves arising from deep intervertebral muscles,” and this is improved with adjusting the adjacent dysfunctional joint.
19. “Joint dysfunction leads to bombardment of the central nervous system with afferent signaling from surrounding intervertebral muscles.” Spinal manipulation reduces excessive afferent signals from adjacent intervertebral muscles which improves altered afferent input to the central nervous system. This changes the way the central nervous system “responds to any subsequent input.”
20. Episodes of acute pain following injury induce plastic changes in the sensorimotor system, prolonging the episode of pain and playing a roll in establishing chronic neck pain conditions.
“The reduced cortical SEP amplitudes observed in this study following spinal manipulation may reflect a normalization of such injury/pain-induced central plastic changes, which may reflect one mechanism for the improvement of functional ability reported following spinal manipulation.”
21. “Spinal manipulation of dysfunctional joints may modify transmission of neuronal circuitries not only at a spinal level but at a cortical level, and possibly also deeper brain structures such as the basal ganglia.” (WOW!)
22. Cervical spine manipulation alters cortical (brain) somatosensory processing and sensorimotor integration.
23. These findings may help to elucidate the mechanisms responsible for the effective relief of pain and restoration of functional ability documented following spinal manipulation treatment.
