Neurological effects of spinal manipulation: What do we know?

Introduction: Spinal manipulation (SM) is a key therapeutic procedure of chiropractic healthcare and a component of osteopathy, physical therapy, Traditional Chinese Medicine and other healthcare professions. It is most commonly used to address musculoskeletal pain and [ublished evidence indicates it has relative efficacy in the management of low back pain, neck pain and headaches of cervical spine origin. Multiple international clinical practice guidelines recommend non-pharmacological management of pain and SM is included as guideline concordant care.
Despite its relative clinical efficacy, the mechanism of action of SM is not well established. Local, articular and fascial changes may be responsible for some clinical effects but there is emerging information suggesting SM affects neurological processes. The goal of this narrative review is to assess the literature for evidence for neurological effects of SM.

Methods: A narrative review followed a literature search of the following databases: CINAHL with full text, MEDLINE with Full Text, PubMed, Springer Nature Journals, Directory of Open Access Journals, Science Direct, Gale OneFile: Health & Med and Google Scholar using keywords including: ("Spinal Manipulation"[Mesh] OR "Spinal Manipulative Therapy" OR "Manual Therapy" OR "Chiropractic Adjustment") AND ("Neurophysiology"[Mesh] OR "Nervous System Physiological Phenomena"[Mesh] OR "Pain Threshold"[Mesh] OR "Proprioception"[Mesh] OR "Autonomic Nervous System"[Mesh] OR "Electromyography"[Mesh])

Results: A review of the literature suggest that SM may impact neurological processes including,
(1) moderating pain by reducing central sensitization and activating descending inhibitory pathways; (2) affecting cortical activity by influencing how the brain processes sensory input and motor control, (3) Autonomic Nervous System output by shifting sympathetic or parasympathetic tone; (4) proprioception and sensorimotor integration, and (5) neuroplastic changes which may explain modification of motor control and pain. Most neurological effects in the published studies reviewed are short-term and clinical impacts are not well understood.

Discussion: There is evidence that SM directly impacts central and peripheral nervous system functions. Clinical observations of the efficacy of SM to address back and neck pain as well as some types of headaches may be explained by neurological effects of the intervention.Mechanisms remain speculative and not fully appreciated.

Robb Russell, D.C. is a graduate of San Diego State University and Los Angeles College of Chiropractic. He practiced privately from 1982 until 2012, joining Southern California University of Health Sciences (SCU) in 2012 and serves as Assistant Vice President & Clinical Chief of Staff at SCU Health. Since 2014 he has held an appointment as an attending chiropractic doctor within the Veterans Administration (VA) Integrated Clinical Practice Residency at VA Greater Los Angeles Healthcare System. He has authored articles published in peer-reviewed, scientific journals, made presentations at healthcare conferences on six continents and has co- authored chapters in two books.