Physiology, Viscerosomatic Reflexes

Excerpt

In 1907, an osteopathic researcher named Louisa Burns observed that "a very important, if not the only, pathway of viscerosensory impulses enters the spinal cord through its posterior roots." She went on to explain that "somato-visceral reflexes are less circumscribed and less direct than are viscerosomatic reflexes" and clarified that "normal visceral activity depends in part upon the stimulation derived from the somatosensory nerves…the possibility of recognition of abnormal viscerosomatic reflexes as an aid in diagnosis is inferred". She had been studying the mechanisms of reflex arcs in animal models to understand better the complex interactions between the viscera, spinal cord, and soft tissues. These landmark statements paved the way for extensive osteopathic study from the likes of future leaders in osteopathic education such as Wilbur Cole, DO, H. V. Halladay, DO, John Martin Littlejohn, MD, DO, William Smith, MD, DO, Irvin Korr, Ph.D., John Stedman Denslow, Ph.D., and William Johnston, DO, FAAO.

The result was an explanation of the phenomenon that would later be known as somatic dysfunction. Somatic dysfunction is defined as "impaired or altered function of related components of the somatic (body framework) system: skeletal, arthrodial, and myofascial structures, and related vascular, lymphatic, and neural elements." the acronym T-A-R-T may help clinicians remember the criteria for the diagnosis of somatic dysfunction: Tissue texture changes; Asymmetry; Restriction of motion; Tenderness (primarily used for specific osteopathic manipulative techniques, namely counterstrain). These criteria are commonly referred to as "TART changes".

One or more of the criteria are required to diagnose somatic dysfunction. It is important to note that tenderness is subjective and considered a controversial criterion. Similarly, the examining physician should consider a finding of focal tenderness concerning the entire clinical picture, developed by way of a thorough history and physical, before establishing a definitive diagnosis of somatic dysfunction. There are many causes of the aforementioned criteria, and thus, there are many causes of somatic dysfunction. Dr. Burns' research explained viscerosomatic reflexes as a contributing etiology. This article portends to explain the anatomical basis for viscerosomatic reflexes, detail their mechanism of development, outline their pathophysiology, and delineate their clinical significance.