MASSAGE THERAPY

Reflex Mechanisms of Massage Therapy, Part II

By Ross Turchaninov, MD

Why do stimuli from the stomach that are delivered to the central nervous system (CNS) radiate to somatic structures, and why in turn are the stimuli from reflex zones activated by the flow of motor impulses to the stomach? The phenomenon of convergence is responsible for this effect. The number of afferent sensory neurons delivering information from peripheral receptors to the spinal cord is greater than the amount of spinal neurons in the posterior horns of the spinal cord. The posterior horns accept and primarily process this information (see figure 2).

In other words, there is more than one sensory neuron in contact with each spinal neuron in the posterior horns of the spinal cord. In this instance, the information brought to CNS by sensory neurons from the stomach excites the entire neural plate of the spinal neuron. The sensory information delivered by sensory neurons from the peripheral receptors in the skin or skeletal muscles also excites the entire neural plate of the same spinal neuron. This stimulation by sensory stimuli from the stomach or reflex zones activates the lower motor cells in the anterior horns of the spinal cord. They generate motor input not only to the location of the original abnormality (the stomach, in our example), but also to the somatic structures innervated by the same segment of the spinal cord.

Figure 2. Convergence of sensory neurons on the neural plate of spinal neuron.Simpler mechanisms of reflex zone formation are applied in cases of somatic abnormalities. This mechanism is responsible for the reflex zones' formation along the pathway of irritated or compressed peripheral nerves. For example, the chronic irritation of the sciatic nerve by overtensed piriformis muscle will produce pathological symptoms through the entire lower limbs. In this manner, irritation of peripheral nerves in the upper part of the body will cause the formation of reflex zones in the lower extremities, supported by the affected peripheral nerve.

Finally, reflex zone formation can be caused by direct compression of the spinal nerve by a herniated disc. As a result of irritation or compression of the spinal nerve, various areas of pathological excitement develop in the spinal cord, especially in the lower motor centers in the anterior horns. Abnormal impulses flow from the spinal cord to the inner organs, and to other parts of the body that are innervated by the affected spinal nerve. Further development follows the same pattern of relation between reflex zones and inner organs or parts of the body as mentioned previously.

Let's now look at another important issue, and ask another important question: "What local events lead to the formation of reflex zones?" First, let's briefly review the physiology of excitation and the conduction of nerve impulses. A nerve impulse or "action potential" is a propagated electrical disturbance originating in the peripheral receptors or in the upper nervous centers; it is conducted through afferent, ascending sensory or efferent, descending motor neurons. Both ascending information to the central nervous system about any kind of peripheral receptors activation, and descending motor commands from the central nervous system, are delivered as a series of action potentials. Any single action potential is the result of changes in the conductance of sodium and potassium through the membrane of the nervous cells. Every action potential has a threshold. A threshold is the firing level of the action potential. This means that if applied stimuli are weak, they are unable to evoke an action potential. In this case, full action potential is replaced by a local response.

A local response is a weak electric excitement that stays within the stimulated receptor, rather than propagating along the neuron. As soon as the stimuli are strong enough, the action potential is generated and conducted through the neuron. This mechanism protects the nervous system from overflow with useless information. Normally, the threshold activation of peripheral receptors has stable electrical magnitude. The continuous radiation of motor impulses to the reflex zones in skin, connective tissue, muscles, or periosteum evokes unusual phenomena in these tissues. The magnitude of the threshold is reduced in all receptors located in these areas. As a result, receptors start to generate action potentials as a response to even the weakest stimulus, even those that normally had subthreshold levels and have never produced action potentials. (Korr, 1947). This phenomenon is called hyperirritability. The affected soft tissues respond by building up tension, especially in contractile elements. Vasoconstriction and local edema are formed, further diminishing blood circulation and decreasing tissue metabolism.

The decrease of the threshold of peripheral receptors, i.e. the condition of hyperirritability, is the starting point of reflex zone formation (Korr, 1947; Glezer, Dalicho, 1955; Kunichev, 1985; Shterngertz, Belaya, 1994; Loginova, 2000). Figure 3 shows how the action potentials are generated, both in the receptors of the normal parts of the body and in the areas of reflex zones.

Figure 3: Formation of action potentials in receptors in normal areas of the body and in reflex zones.In 1947, in a series of brilliant clinical experiments, Prof. I. Korr showed that hyperirritability is a key to understanding reflex zone formation. In his experiments, Korr inserted microelectrodes in muscles with clinical symptoms of hypertonic abnormalities, then exposed his subjects to different types of stimulation: physical activity, decreased and increased temperature, loud sounds, bright light, etc. When subjects were exposed to each of these stimuli (even visual and auditory) the skeletal muscles in the area of reflex zones reacted with increased tension, which was detected by electromyography. This caused the additional decrease of peripheral circulation in already-affected areas. Thus, as Prof. I. Korr showed, any type of sensory stimulation of the CNS causes the further development of reflex zones in the tissue which are no longer protected from theactivation of peripheral receptors by subthreshold stimuli.

A number of clinical abnormalities can be found found in the areas of reflex zones in the skin, connective tissue, skeletal muscles and periosteum. During diagnostic examination, the practitioner should detect all abnormalities and record them on prepared diagrams of the body. At the end of the diagnostic examination, the practitioner will have a complete picture of somatic abnormalities for the patient. Such an approach to diagnostic examination allows the practitioner to formulate the optimal treatment protocol.

I. Cutaneous Reflex Zones

A. Visual examination of the skin. Have bright light in the room for visual inspection of the cutaneous reflex zones. Look for areas revealing the following symptoms:

1. Local hyperemia, paleness or pigmentation. Hyperemia is sign of overactivity of the sympathetic of the part of the autonomic nervous system, insufficient venous drainage, or chronic inflammation. Paleness is sign of overactivity of the parasympathetic nervous system or insufficient arterial supply. Pigmentation usually accompanies skin aging. However, in some cases the excessive local pigmentation is a pathological symptom. The best example is pigmentation on the lower 1/3 of the leg in the patients with varicose veins.
2. Areas of hairless skin. In the areas of reflex zones, the practitioner can detect regions with lesser amounts of hair on the skin surface. The classical example of this symptom is areas of hairless skin on the legs of patients who suffer from thromboangiitis obliterans (i.e., Buerger disease).
3. Stretch marks. Long-lasting somatic abnormalities in the areas of cutaneous reflex zones can cause stretch marks. This symptom has limited clinical value when estimated alone. In the majority of cases, stretch marks do not have any direct connection with cutaneous reflex zones; rather, they are a result of accelerated growth during puberty, cellulite or pregnancy. However, stretch marks may play role in the diagnostic procedure when they are examined along with other local abnormalities in the areas of cutaneous reflex zones. They have more clinical value when detected in unusual locations or when the patient is male.
4. Glossy skin. Glossy skin is a symptom of peripheral edema.

B. Palpatory examination of the skin. Palpatory examination of skin is always conducted after visual examination. Conduct the palpatory examination after placing the patient in comfortable position. Let the patient relax for two-to-three minutes. The palpatory examination of the cutaneous reflex zones must be conducted in comparison to the opposite side of the body, if the process is unilateral, and in comparison with neighboring parts of the body if the process is bilateral. All palpatory examination of the skin must be done with light touch or pressure, because the practitioner examines the most superficial layer of soft tissues.

1. Coarse superficial epithelium. This is very valuable symptom. The sensation of skin roughness often accompanies the cutaneous reflex zones. In some cases, this roughness matches exactly the borders of cutaneous reflex zones. Patients, especially female patients, even complain about this symptom during consultation, noting that topical lotions did not bring any improvement.
2. Edema. Insufficient venous blood and lymph drainage will cause an accumulation of fluid in the subcutaneous tissue and skin.
3. Hyperthermia or hypothermia. See above, in the section on visual inspection.
4. Sudomotor reactions. Sudomotor reactions are increased or decreased sweat production in the areas of cutaneous reflex zones. A decrease in sweat production can be also detected in the areas of coarse superficial epithelium.
5. Hyperaestesia. Hyperaestesia is a condition in which a quick but light stroke over the skin surface is felt as a sharp pain. This is a clinical sign of neurological abnormalities in the skin.
6. Hyperalgesia. Hyperalgesia is a condition in which light pressure causes severe pain. This is also a clinical sign of neurological abnormalities in the skin.
7. Cutaneous trigger points. Cutaneous trigger points are one of clinical examples of hyperalgesia.
8. Paraesthesia. Paraestesia or a tingling sensation is a classical sign of neurological abnormalities in the skin.
9. Numbness. Numbness is also clinical sign of neurological abnormalities in the skin.