V. THE CONNECTIONS:

TRACING SYMPTOMS TO ORGANIC DISEASES

In the preceding chapters, we have looked at the neurological and structural changes that have affected the development of the human species. We have seen that the interrelation between muscles and muscles, joints and joints, and bones and bones have come about as a result of the phenomenon of adaptation through the course of human evolution. In fact, the interrelation between the different structures of the body is not limited to associations between similar tissues but also extends to dissimilar structures such as the interrelation between the skin and the underlying muscles. When painful and damaging stimuli are applied to the skin, the body responds by a strong contraction of the muscle(s) to withdraw that part of the body from the stimuli. This quick involuntary motor reflex is a defense mechanism called "flexor reflex."

Sensations of pain and temperature, as well as any other modality of sensation, will elicit a response in the central nervous system. Some of the primary reflexes, like the sensation of pain and temperature (which are associated with the lateral spinothalamic tract), will take place at the spinal cord level. At this level, the incoming sensory neurons will synapse with internuncial neurons in the dorsal horn. Internuncial neurons will then synapse with the motor neurons whose axons will exit through the ventral root and go directly to the voluntary muscles associated with the skin area where the painful or burning stimuli originated. If the pain sensation is extreme, many more muscles and even the entire body will become involved in the quick reflex of withdrawing from the painful stimuli. Other modalities of sensation, such as light touch, may elicit a weaker and localized flexor reflex.

Not all sensory neurons will synapse with internuncial cells. Sensory neurons for proprioception, vibratory sense, and fine touch (stereognosis) will not synapse in the spinal cord. Axons will pass immediately into the dorsal white columns and ascend all the way up to the medulla oblongata and terminate in the nucleus gracilis and nucleus cuneatus (see Figure 1-1).

The second-order neurons arising from the nuclei gracilis and cuneatus cross over to the other side of the medulla by way of the internal arcuate fibers. These fibers form an ascending bundle, the medial lemniscus, which has no collateral branches and terminates directly in the ventral posterolateral nucleus of the thalamus. In the thalamus, second-order neurons synapse with third-order neurons, whose fibers ascend to the post-central gyrus via the internal capsule (Somatic Sensory Area - 3, 1, 2). At the level of the medulla, there exist some cells in the rostral parts of the nuclei gracilis and cuneatus which give rise to fibers that terminate in the dorsal accessory olivary nucleus. The dorsal accessory nucleus, as well as the medial accessory and part of the principal inferior olivary nucleus, projects fibers that end in the cerebellar vermis. These fibers, which are integrated into the spino-olivocerebellar pathway, reach the cerebellum through the contralateral inferior cerebellar peduncle and are mostly concerned with the relay of flexor reflex stimuli.

The accessory cuneate nucleus, located lateral to the cuneate nucleus in the medulla, receives afferent sensory fibers from spinal ganglia just as the cuneate nucleus does. The fibers from the accessory cuneate nucleus relay uncrossed information to the cerebellum from muscle spindle receptors, golgi tendon apparatus, and cutaneous receptors.

Modalities of sensation are also transmitted through the spinocerebellar pathway (see Figure 1-4). The cells of the dorsal nucleus of Clarke, located at the base of the dorsal horn from L2 to C8, give rise to the uncrossed fibers of the posterior spinocerebellar tract and the crossed fibers of the anterior spinocerebellar tract. The posterior and anterior spinocerebellar tracts supply the cerebellum with proprioceptive information from receptors located in the muscles, joints, and tendons as well as information from touch and pressure receptors that are found in the overlying skin. Impulses transmitted by these tracts help control posture and the movement not only of limb muscles but also of abdominal, dorsal, and thoracic muscles.

As we can see, sensory nerve endings from muscles, tendons, joints, and cutaneous receptors are all interrelated, and the stimulation of afferent cutaneous nerve endings has a concomitant effect on the underlying tissues (muscles, tendons, and joints). The points of convergence between the skin receptors and the receptors found in the underlying tissues are most probably located at the level of the spinal cord via the internuncial cells (primary flexor reflexes). Afferent cutaneous stimuli also probably travel all the way up to the brain stem and reach different nuclei in the upper portion of the reticular formation. These nuclei receive incoming impulses from various muscles, tendons, and joints. In addition, most of the ascending sensory tracts are somatotopically organized in the spine, medulla, cerebellum, thalamus, and cortex, hence resulting in the further accentuation of the synergistic response of specific muscles, tendons, and joints to the stimulation of well-defined areas of skin.

The sensory nerve endings, which are located in the skin surrounding the joints, are stereoscopically organized. This means that the stimulation of cutaneous nerve endings covering a joint will also affect the immediate underlying segment of that joint. The stimulation of cutaneous nerve endings will generate in the body a variety of reactions, all of which are functions of the type of stimuli, namely pain and temperature sensations, touch, vibration pressure, fine touch, or a combination thereof. The intensity of the response will depend on the number and location of the nerve endings being solicited. For instance, the tip of each finger contains a large number of nerve endings, and the stimulation of a finger tip will elicit a stronger response than the stimulation of a similar area of skin surface on the back of the shoulder.

We have seen in Chapter II that the ascending reticular formation relays all the modalities of sensation to the brain stem reticular formation. The cells that are located in the posterior horn (lamina V) give rise to fibers that ascend in the anterolateral part of the spinal cord and terminate at different brain stem levels. In the medulla, a large number of spinoreticular fibers project to the gigantocellular reticular nucleus. The lateral reticular nucleus of the medulla receives collateral branches from the spinothalamic tract, and the parvicellular reticular nucleus receives collateral fibers from visceral, auditory, vestibular, and trigeminal sensory pathways. From the lateral reticular nucleus, impulses are relayed to the cerebellum. It should also be noted that the afferent fibers that terminate in the lateral reticular nucleus are somatopically organized.

Some spinoreticular fibers terminate in the pontine and mid-brain reticular nuclei. In the mid-brain, the pedunculopontine nucleus receives fibers from multiple areas, including the cerebral cortex and the substantia nigra. This nucleus is considered to be a locomotor center. In the thalamus, the rostral interlaminar thalamic nuclei receive afferent fibers from the brain stem reticular formation, which ascend in the central segmental tract, mostly uncrossed. All the modalities of sensation from both inside and outside the body eventually end up in the rostral intralaminar thalamic nuclei. Thus, all afferent impulses originate in the muscles, tendons, viscera and skin.

Some modalities, such as proprioception and stereognosis, are immediately processed at a higher level in the central nervous system (medulla, cerebellum, and thalamus) because they require more elaborated centers of analysis and centers of coordination for the incoming messages. This is why the axons of the first-order neurons terminate directly in the medulla (nuclei gracilis and cuneatus). On the other hand, primary sensations such as pain, temperature, and simple touch represent crude sensations, which are partly dealt with at the spinal cord level through different arc reflexes involving internuncial cells. When those sensations are relayed to a higher level in order to supplement other incoming messages, the stimuli will reach the thalamus and the cerebellum through their respective spinothalamic and spinocerebellar pathways.

We have concluded in Chapter IV that the association between muscles may be ipsilateral, contralateral, or a combination of both, depending on the activity and functional needs of the body at that particular time. The associations between bones and bones and between joints and joints are mostly ipsilateral.

We have just seen that the skin and the underlying tissues are closely related and that their sensory nerve endings may be activated by any external or internal stimuli. Some of the receptors are located in the skin (hair end-organs, Meissner's corpuscles, Pacinian corpuscles), some in the tendons (Golgi tendon apparatus), and some in the joints (Ruffini's end-organ type of receptor). Other receptors are found in the muscles (muscle spindle receptors, which transmit signals to the spinal cord and cerebellum) and others in all the tissues of body (free nerve endings). All the information that is passed by these receptors is integrated in the "skin-muscles-tendons-joints-ligaments complex" to control body mechanics.

Spastic or over-distended viscus or diminished blood flow to visceral tissues may produce visceral pain sensations that will reach the spinal cord through afferent visceral autonomic fibers. Sympathetic and sacral para-sympathetic nerves reach the spinal cord, and some cranial nerves like the glossopharyngeal (IX) and vagus (X) reach the brain stem. In the spinal cord, visceral autonomic fibers join the lateral spinothalamic tract with the other incoming pain fibers from the skin surface.⁴³ Parietal pain sensations from the peritoneum, pleura, and pericardium reach the spinal cord through skeletal nerve fibers. Visceral and parietal pain sensations, however, are only one type of modality among all the sensations that reach the spinal cord. The deep sensibilities that originate in the organs and other internal tissues are the same as the ones that originate in the skin, such as pressure, vibratory, and thermal sensations. These deep sensations also reach the spinal cord through the afferent visceral autonomic fibers.

There is indeed a constant flow of afferent and efferent stimuli which is traveling between the central nervous system and the different organs, the smooth, skeletal and cardiac muscles, the blood vessels, the sweat glands, and the pilo-erector muscles. It is also important to remember that not one single ascending or descending pathway in the central nervous system is totally isolated or independent from the other pathways. The reticular formation and the sensory, autonomic, and motor pathways are all intermingled, therefore making them complementary to and supportive of each other.

In this neurological network where many tissues are interconnected through multi-synaptic pathways, sensory stimuli originating in the skin may branch off in the spinal cord and travel in many directions. We have seen that they may relay impulses to the ascending or descending reticular formation. They may also relay information directly to the intermediolateral nucleus in the lateral horn and induce a visceral response by way of the pre-ganglionic sympathetic fibers. The sensory stimuli may also reach the sacral autonomic nuclei (segments S2, S3, S4), which give rise to pre-ganglionic parasympathetic fibers. Figure 5-1 represents a typical example of somatovisceral reflex where the internuncial cells relay the incoming stimuli to the intermediolateral nucleus.

Afferent autonomic fibers may relay visceral information to the intermediomedial nucleus in the spinal cord (Lamina VII), and some of those visceral sensations may reach the brain stem. Other visceral fibers may synapse with internuncial neurons and relay the visceral stimuli to sensory or motor neurons and also to autonomic efferent fibers (see Figure 5-2). In this case, visceral impulses may give rise to viscero-somatic signs and symptoms.

Numerous researchers have investigated the field of somatovisceral reflexes through clinical trials and experiments.⁴⁴ There is a general agreement that the stimulation of afferent nerve endings has a direct effect on visceral functions. Other researchers have also described surface areas of the body which are associated with referred pain from different organs based on the embryological development of an organ and the segmental field or dermatome associated with it.

Our extensive clinical experience in the fields of viscero-somatic signs and symptoms and somato-visceral reflexes has given us the opportunity to localize specific cutaneous areas, which are associated with particular organs. We have found that organic diseases, which may encompass simple organic malfunctions as well as true pathologies, will be reflected on well-defined areas on the body and that somato-visceral reflex points happen to cover exactly the same areas as viscero-somatic indicators. Different signs and symptoms such as referred pain sometimes reveal these indicators, but referred pain by itself is too often an elusive indicator that may appear in the advanced stages of a disease. Muscle reflexes, which may be elicited by the stimulation of afferent nerve endings covering the body, have proven to be by far more reliable in the elaboration of a map of the cutaneous areas that are related to organs. The skin areas that receive organic impulses and coincide with the major gateways to the organs are shown in Figure 5-3 through 5-8. Some of these skin areas have previously been described by a number of researchers (Rees, Bennett, etc), but many of these skin area depictions represent new findings.

The skin areas and the underlying muscles and their associated deep tissues are often the sites of irritation, inflammation, congestion, pain, oedema, or other signs and symptoms when the associated organs are irritated, congested, inflamed, or have developed some form of pathology. The following are a few of the abundant examples of these connections:

• The side of the face is associated with the ovary (see Figure 5-6 and 5-7) and thus may develop pimples, swelling, and any symptoms during the ovulatory phase.
• Hoarseness and chronic throat irritation is often associated with prostatic problems (see Figure 5-5 and Figure 5-6).
• Chronic pain or oedema in the legs is frequently related to bladder irritation or infection (see Figure 5-3).
• A swollen ankle is often related to gynecologic problems of the ovary/uterus on the same side of the body (see Figure 5-3).
• Elbow or knee pain, without a history of old or recent trauma, may be an indication of a thyroid imbalance on the same side as the affected joint (see Figure 5-3 and 5-4).
• A kidney problem may induce recurrent torticollis (see Figure 5-5).
• Pain above the eyes or headaches centered around the superciliary ridge are often related to duodenal problems (see Figure 5-6).
• Constipation, diarrhea, or any malfunction of the colon induces back pain and tension or pain in the muscles and skin areas of the thighs and shoulders (see Figure 5-5 and Figure 5-8).
• A malfunction of the adrenal gland may produce a chronic pain at the superior angle of the scapula (see Figure 5-8).
• Pain around the coracoid process with a limitation in the range of motion of the shoulder joint may be associated with stomach and/or pyloric problems (see Figure 5-4).

Organic malfunctions or pathologies will not always produce symptoms in the first stage of the disease. In some instances, the only initial indication of a problem may be vague complaints by the patient of sporadic lower back pain, tension in the neck, or headaches. Even without visible signs or symptoms, however, the sick organ will project warning signals to the nerve endings of the skin, muscles, and deep tissues related to the organ in question. These warning signals can be detected by probing the related nerve endings through the testing of muscle reflexes.