The ANS is comprised of the sympathetic and parasympathetic nervous systems. In physical therapy school, I was taught to look at the autonomic nervous system (ANS) as an up or down -regulator of homeostatic function. Its functions include pupil dilation, gut mobility, force of cardiac contractions, and much more. Early into my clinical practice as an Orthopedic Manual Physical Therapist, I did not perceive the connection between the sympathetic nervous system (SNS) and the musculoskeletal system. Entrapment of the sympathetic nervous system can be a contributing factor in anything from peripheral nerve pathology to chronic regional pain syndrome. Understanding the different components of the sympathetic chain can lead to better treatment strategies.
Anatomy & Function
The sympathetic nervous system lies just anterior to the costotransverse joints from T1-T12. Each region of the sympathetic nervous system corresponds with a region of the body. T3-T7 innervates the upper extremities, T7-T12 innervates the lower extremities, and the entire chain (T1-T12) innervates the trunk. In a healthy population, normal mobility exists in the SNS allowing information to flow uninterrupted. In the presence of chronic pain, the spinal inter-neurons may become more sensitive to stimuli. This phenomenon is known as central sensitization. The patient may develop hyperalgesia, allodynia, and have decreased pain thresholds. These symptoms are due to SNS dysfunction and can manifest in our musculoskeletal patients. No one understands the exact interaction between the sympathetic nervous system and pain, but we know there is a relationship. By altering the function of one, we can change the function of the other.
Patients who present with central sensitization can benefit from manual therapy. Since we know that each region of the SNS corresponds with a body region, manipulation or mobilization should be directed accordingly. A patient with hyperalgesia of the upper extremity will better benefit from a manipulation of the upper thoracic vertebrae. Contrarily, those with pain alterations of the lower extremity will benefit from a manipulation of the lower thoracic vertebrae. If the patient presents with CRPS, the patient may not tolerate the force of manipulation. Joint mobilizations of the respective area will suffice.
As therapists, people often need proper "validation" for performing a manipulation. Thoracic manipulations are very safe and mobilizing the SNS can help increase the pain threshold to provide a window of opportunity to maximize the effects of your treatment.