Chiropractic and Clinical Neuroscience

The first chiropractor, D.D. Palmer sought explanations within the field of 19th-century neuroscience to explain his clinical observations when applying spinal manipulation to his early patients. He developed a neuro-biomechanical model to explain these observations, and named it the Vertebral Subluxation. This model/paradigm seemed to suit the information about neuroscience known at the time. This model served the chiropractic profession well until demands in the 1930’s emerged for randomized controlled clinical trials (RCT) to prove the claims of health care practitioners, pharmaceutical and biotechnology companies. Developments in neuroscience also stagnated throughout the middle of the 20th Century.

By the 1990s scientific investigation of the nervous system moved to examine the brain and its connections by more complicated imaging methods and tools (MRI, fMRI, PET scans, Tractography, QEEG). Investigators began to realise that damage to the nervous system could not only come from severe trauma (major head injury, major blood vessel injuries such as stroke or aneurysm), significant disease (encephalitis, etc), or autoimmune inflammatory disease (MS, MND), but from much more innocuous injury (mild head injury in the form of concussion), metabolic disorders (nutritional and neurochemical disorders), low-grade viral infections, resulting in much “softer” but life-altering disorders. Researchers also began to observe the impact of the loss of sensory input (vision, hearing, smell, taste, gravity, somatic sensations such as proprioception) on the function of the brain. However, perhaps the most impactful discovery within the 20th Century was that the nervous system adapts and rebuilds through constant neuroplasticity (the making and breaking of connections within the nervous system).

Following decades of intensive brain research, it is now understood that the human brain localises the neural networks for many different functions into one or other of the cerebral hemispheres. Click on the pictures below to look at the papers, if you are interested. You can even read how each side of our brain motivates us to sit on different sides of a room, based on what we think we are about to see or hear!!

This led to Hemisphere Laterality or Brain Asymmetry Hypotheses. Researchers and clinicians began to observe more detailed changes in the way the brain, particularly each hemisphere, works under normal and stressed situations. It became apparent that sensory information from each half of the body was processed in subtly different ways by the two cerebral hemispheres.

Carrick hypothesised that, in some cases,  there might be both beneficial and deleterious nervous system effects of sensory input such as spinal manipulation, or other forms of manual therapy. He also postulated that the two hemispheres may process sensory-motor integration differently. Click on the image below if you are interested in reading the results of his study.

The results of Dr Carrick’s Ph.D. findings were controversial, and in effect, paradigm-changing for the chiropractic profession. His research suggested that chiropractors should be aware of both the powerfully beneficial and adverse effects of spinal manipulation. He suggested that chiropractors should be trained further in their post-graduate studies to assess whether a patient may need a more titrated approach when receiving manual therapy. Chiropractors provide a range of manual therapy options from gentle, long lever or light touch techniques, to more robust manipulative techniques. Dr Carrick’s early research provided some guidelines for these varying clinical approaches. Dr. Noone completed his clinical neuroscience training under Dr. Carrick. Dr. Noone employs a titrated sensory afferentation model, based on assessing the state of the receiving individual’s nervous system.

Dr. Carrick and his research teams are spending much of their time designing clinical research methodologies to investigate diagnostic and therapeutic hypotheses. In fact, this research is providing clinical therapeutic strategies other than manipulative therapy of the spine, when attempting to treat complex neurological conditions in a non-pharmacological (drug) or non-surgical manner.

A list of research publications by Dr. Carrick and others will be provided on this page in due time.

Abstract