Visceral Responses to Spinal Manipulation
Written by Editor   
Friday, October 14, 2016 12:00 AM

Spinal manipulation is generally accepted as one reasonable treatment option in the management of musculoskeletal disorders such as low back pain and neck pain. Some evidence also exists that certain visceral disorders benefit from spinal manipulation. However, the mechanisms by which spinal manipulation might alter visceral function, and so impact visceral disease, remain unclear. Therefore, in this paper, we review the currently available literature concerning visceral responses to the application of mechanical stimuli to the spine and paraspinal tissues.

While spinal manipulation is widely seen as a reasonable treatment option for biomechanical disorders of the spine, such as neck pain and low back pain, the use of spinal manipulation to treat non-musculoskeletal complaints remains controversial. This controversy is due in part to the perception that there is no robust neurobiological rationale to justify using a biomechanical treatment of the spine to address a disorder of visceral function.

This paper therefore looks at the physiological evidence that spinal manipulation can impact visceral function. A structured search was conducted, using PubMed and the Index to Chiropractic Literature, to construct of corpus of primary data studies in healthy human subjects of the effects of spinal manipulation on visceral function.

The corpus of literature is not large, and the greatest number of papers concerns cardiovascular function. Authors often attribute visceral effects of spinal manipulation to somato-autonomic reflexes. While this is not unreasonable, little attention is paid to alternative mechanisms such as somato-humoural pathways. Thus, while the literature confirms that mechanical stimulation of the spine modulates some organ functions in some cohorts, a comprehensive neurobiological rationale for this general phenomenon has yet to appear.

Notwithstanding substantial interest by manual medicine practitioners in somato-visceral disorders, there are relatively few basic physiological studies in humans to guide clinical practice. The corpus of somato-visceral studies is characterized by small cohorts of subjects, uncontrolled trials and one time pilot exercises with no subsequent follow-up. The field has been slow to adopt new technologies. Only recently have teams of researchers appeared with the sustained interest, expertise and resources to pursue meaningful programmes of research.

The greatest number of physiological studies has focused on cardiovascular function, with few investigations of other organ systems. There is a justifiable interest in autonomically-mediated phenomena. However, somato-humoural and non-autonomic neural mechanisms of spino-visceral interactions remain largely unexplored.