A Neurological Look at Chiropractic

By: Kurt Vreeland, DC, DICAK, DABCN, DACAN, FACCN

Throughout the history of Chiropractic, a common theme in trying to alleviate patient suffering has been the correction of posture. Regardless of the particular technique practiced, there always seems to be a common denominator in the restoration of “normal” posture. Sometimes the problem is that we can’t agree as to what is normal. How many times have you seen an X-ray which, for all intents and purposes, looks “normal,” but the patient still complains of pain? The simple answer is that we really can’t compare one person to another regarding their structure or their neurological system. It would be like trying to compare different types of noses, or different types of hair color. What is a “normal” nose or hair color? Human anatomy may have similar characteristics, but their functional ability will be quite unique to the individual, like the natural talent of a world-class athlete. The human nervous system is no exception: like the color of your hair or the shape of your nose, it is a product of millions of years of genetic evolution. Therefore, the only comparator we have is the evaluation of one side of the individual to the other; right to left, front to back. We can only generalize from person to person.

se21#5 Vreeland new look old problem - Fig 1The nervous system controls bodily activities. This is achieved by controlling: skeletal muscle contraction, contraction of smooth muscle of the internal organs, and the secretions of the exocrine and endocrine glands in many parts of the body. Most activities of the nervous system are initiated by sensory stimulation received by mechanoreceptors; visual, auditory and tactile. The skeletal muscles are controlled from many different levels of the central nervous system (CNS), including the spinal cord, the midbrain, the basal ganglia, the cerebellum and the motor cortex.

The human neurological system is designed for only two things (Fig. 1):

  • Receive information
  • Transmit information

It is the cumulative effects of all the afferent “sensory” input that determines the amount of function; including pain and suffering. This central integrated state of the nervous system is similar to a dynamic “set-point” from which the body runs all its functions. However, habitual patterns can develop within this set point. Habituation, or condition, develops as a result of a constant repetitive firing pattern. This pattern becomes a “learned” behavior; right or wrong, appropriate or inappropriate. In other words, the body will adapt to just about anything.

se21#5 Vreeland new look old problem - Fig 2As Chiropractors we learn how to understand body language. We use tools like static palpation to elicit pain or to feel muscle tonicity, motion palpation to detect discrepancies in segmental movement, postural analysis to view structural and soft tissue stress points, leg length checks for reactive response to stimuli, manual muscle testing to perceive a relative strength, etc. For the most part, the information we receive by “reading” the body comes from the mechanoreceptors in and around the joints. These mechanoreceptors detect mechanical deformation of cells and tissues. The information is relayed to the somesthetic area (sensory cortex) of the brain (Fig. 2). From here the important sensory information is channeled into the proper motor region to cause the appropriate response. The response will always be appropriate for the information received.

It takes sufficient excitation of the mechanoreceptor above its resting threshold to activate a reaction or response. Once activated, the sensory input can cause an immediate motor reaction (deep tendon reflex). Its memory can be stored in the brain for minutes, weeks, or years (postural muscle tone).

So, how can anything go wrong? Relaying neurologic information is like transmitting a verbal message around a room full of people. As it gets passed from point to point, there is a chance for error, especially if one person has a hearing loss (receiving) or a speech impediment (transmission)—the structure is there, but the function is faulty.

Any aberrant information received or transmitted causes aberrancies in function somewhere in the body. This can, for example, manifest in the brain stem to cause a cascade of autonomic concomitants, such as circulatory change or nausea and vomiting. In fact, most, if not all, of the symptoms that a patient will present with are concomitant results of aberrant neurological firing. These concomitant “symptoms” may tend to lead one astray, for the site of the actual problem is usually far removed from the symptom. For example, tachycardia “may” be caused by an upper dorsal subluxation; the old Meric System. It “might” also be caused by a subluxation anywhere else in the body which results in aberrant information exchange in the brain stem to cause a cascade of autonomic events—one of which might be tachycardia. Most of the time the patient doesn’t even know that he or she has a problem “far removed from the symptom.”

Our sensory-motor system continually responds to daily stresses and traumas with specific muscular reflexes. Repeated again and again (for months and even years), this habitual muscle contraction—conditioned response—which we cannot voluntarily relax, may not necessarily be “re-set” by a few Chiropractic adjustments or soft tissue applications. The result is chronic stiffness, restricted range of motion, and pain.

One important question that arises is: Why does one patient respond so well, and yet another not so well with seemingly similar problems?

The answer becomes quite simple when one realizes that each person’s neurological system has inherent differences and the input (the treatment) may or may not be sufficient to correct or change the habitual neurologic pattern, or decondition the old pattern and recondition a new pattern. Now the question becomes: How does the treating physician maximize the global input of receptors, regardless of what the patient complains of? Since people stand and move about, some more than others, a most logical starting point is to look at where they contact the ground. This is the platform that keeps us erect in the earth’s gravitational field. A magnificent structure richly endowed with mechanoreceptors—the foot!

The sensory signals from the mechanoreceptors in and around the joints of the foot and from the footpads play a strong role in controlling foot pressure, rate of stepping, as well as postural and locomotive muscle responses. The locus of pressure on the foot pad determines the direction to which the leg will extend; pressure on one of the feet causes movement in that direction, an effect called the “magnet reflex.” A series of complicated reflexes involving the foot play an important role in the “cord righting reflex,” and the rhythmic stepping movements of gait. Everyone who has ever held an infant knows that if you support that infant so that the pads of the feet contact the ground there is a very powerful extensor response.

se21#5 Vreeland new look old problem - Fig 3Excessive pronation, the most common structural distortion of the foot, is a prime contributor to aberrant information transmitted to the CNS. Hyperpronation stretches the bone-to-bone ligaments with their type III mechanoreceptors which has an inhibitory effect of muscle innervated by the same cord levels (muscles in and around the pelvic bowl and lower extremity). Excessive pronation will also create uneven distribution of the footpad pressure, thus affecting muscle balance through the magnet reflex. One physical manifestation of this is excessive asymmetrical callus formation (Fig. 3).

The cerebellum is 99% dependent on information it receives from joint mechanoreceptors and muscle spindles. In turn, it sets and maintains the tone of the antigravity musculature, most powerfully the muscles of the back and neck. With any aberrant input, such as a fallen arch or pronated ankle, the cerebellum, through a purely reflex mechanism, will adjust the posture accordingly (Fig. 4). A common postural distortion pattern is:

  • Anterior cervical translation
  • Thoracic extension
  • Anterior pelvic translation

se21#5 Vreeland new look old problem - Fig 4In time, this aberrant muscle tension can alter the axis of rotation of spinal joints which leads to a decrease in motion with an increase in joint tissue breakdown and resultant increase in nociception input, i.e. pain. The symptom—pain in the back, neck or quite possibly anywhere else, which has motivated the patient to seek your help—may now be far removed from the problem.

It is evident that the feedback (from the foot to the cerebellum) and the feedforward (from the cerebellum to the antigravity musculature) must be intact, just as all other feedback mechanisms must be intact.

We have a most difficult and demanding job. We have to find and restore normal function. Recent advancements in neurophysiology allow us to explain our results in a more scientific way. Regardless of our technique or philosophy, the common thread in all of us is that we affect the central nervous system by restoring the “normal” transmission of neuronal information, both sensory input and motor output, to enhance normal appropriate function, thus relieving the pain and suffering of our patients.

In order to achieve maximum results, the doctor must maximize the probabilities of affecting the central integrated state. To consider the architecture and neurology of the foot and ankle will greatly enhance the probability of changing this central integrated state, just by the sheer number of times the foot hits the ground. Only by supporting all three arches of the foot can you maximize the full potential of these neurological receptors. Accomplishing this will just increase your chances of success, like receiving a whole lot of lottery tickets for one price. On the other hand, not considering the effects of global afferent “sensory” input, especially from the feet, on the total person, is like receiving only one lottery ticket for the same price. Here’s an opportunity to hedge your chances for a positive patient outcome.

Custom-made, functional orthotics by Foot Levelers are the most cost-effective neurological rehabilitative product available to our profession due to the frequency of afferent firing from the foot/ankle complex. It should be noted that these orthotics are the only ones I have found which provide support to all three arches of the foot. There are other rehab products that do affect neurologic input, like wobble boards, but they depend on patient compliance and do not address the most common pedal deformation (excessive pronation). The ease of Foot Levelers takes the problem of patient compliance out of the picture. Custom-made, functional orthotics will enhance your specific Chiropractic adjustments to ensure the highest probability of a successful patient outcome.

With this new understanding of the cause and effect in the neurophysiological system, take a new look at your patients’ feet. You will have a new edge on handling an old problem.

References

  1. Kandel, Schwarz, and Jessell. Principles of Neural Science, third edition
  2. Guyton. Guyton’s Physiology, 1993
  3. Willis, Grossman. Medical Neurobiology, third edition
  4. West. Physiological Basis of Medical Practice, twelfth edition

About the Author

Dr. Kurt Vreeland is a 1976 graduate of Logan College of Chiropractic. He has had postdoctoral training in Chiropractic neurology, applied kinesiology, Chiropractic orthopedics, physical therapy, and acupuncture. He is a Diplomate of the following: the International College of Applied Kinesiology; the American Board of Chiropractic Neurology; and the American Chiropractic Academy of Neurology. He is a Fellow of the American College of Chiropractic Neurology.

Dr. Vreeland has had experience as a Team Doctor for the U.S. Olympic Alpine Ski Team, the U.S. Olympic Ski Team, and the U.S. Olympic Nordic Combined Team. His articles have been published in the Collected Papers of the International College of Applied Kinesiology and Neuromuscular Therapy Update.