Skin, fascias, and scars: symptoms and systemic connections.

Finally, we analyze the problems that can arise from abdominal visceral surgery. Communication between the viscera and the brain is continuous. The brain receives (and responds to) continuous dynamic feedback of afferent visceral signals through neural and humoral pathways. 42 Spinal visceral afferents project themselves toward the dorsal horns of the spinal cord, into the spinothalamic tract; humoral information is processed through circumventricular organs and within other brain regions, including the hypothalamus. 42 The visceral efferents, especially those of the sympathetic system, are the solar ganglia, the superior mesenteric ganglion and the lower one, and the sacral ganglion. 40 The incidence of detection of adhesions after visceral surgery may rise to 100%, depending on the texts examined. 43 , 101 , 102 Necessarily, we identify symptoms resulting from the scar, such as meteorism, irregular bowel movements, chronic abdominal pain, digestive disorders, and intestinal obstruction. 43 Abdominal fascial connections with the sternum and the pubis will determine postural problems, back pain, and dysfunctions in walking. The distal rectus abdominis sheath has a direct connection with the gracilis and adductor longus muscles through fascial connections; this relationship is important to distribute the load of the step between the trunk and the lower limbs. 103 Over time, an alteration of the loads may lead to pubalgy, and even to back pain. The scar resulting from a cesarean section may lead to infertility, menorrhalgia, lower abdominal pain, dyspareunia and dysmenorrhea, endometriosis, and pelvic pain. 104 – 106 A pelvis that is not physiologically mobile will result in dysfunctions of the respiratory diaphragm, the thoracic outlet, the mouth floor, and the reciprocal tensional membrane. 40 Therefore, a visceral problem can alter the structure. It is worth remembering that there is a convergence of viscerosomatic information in the spinal cord. 107 , 108 An abdominal scar may draw the inferior mesenteric plexus, bringing about symptoms related to the sympathetic nervous system and to the correlated visceral and somatic spheres (T11–L2), as studies on cadavers have already proven. 109 Therefore, visceral adhesions can affect the sympathetic nervous system, with varied symptomatology such as vertebral stiffness corresponding to the metameric innervation. 110 The spinal trigeminal nucleus receives visceral information via the vagus nerve (and the glossopharyngeal nerve). This may lead to a malfunction with symptoms related to the trigeminal system, from a toothache to a headache, and from painful chewing to optical problems. 111 The general rule is to check scars, even when they seem to be normal. Research has already proven that even if a scar appears to be hypotonic to the touch, its electrical activity is higher in a patient who has been ordered to move actively than the electrical activity recorded, in the presence of undamaged skin, in the same person performing the same movements. 112 This applies to every part of the body. To conclude, we underline that the fascias envelop the viscera and that the fascia would seem capable of conducting electrical activity under mechanical stimuli, giving rise to additional symptoms. 113

The skin is an organ that can influence body homeostasis. It is good practice, when evaluating the clinical picture of a patient, to always ascertain the presence of scars. Looking at the patient as a system and not just as a symptom or a symptomatological segment will help the clinician, and all those professionals who use manual techniques, to find a more effective treatment. A scar can produce different symptoms, which can affect the neurological sphere, the fascial, and the visceral area. The skin surface is a means to communicate with the nervous system, to understand it, and to give therapeutic information. We can conclude by affirming that the skin and the fascias represent the skeletal system of the nervous system.

There are four main stages in skin healing: hemostasis, inflammation, proliferation, and remodeling. 15 The healing process of the skin surface begins with the lesion, when the bleeding conveys the blood elements in the area of the injury (blood platelets, fibrin, fibronectin, glycoprotein), trying to produce a parallel vasoconstriction. 15 The blood platelets come in contact with the exposed collagen and with other elements of the extracellular matrix. 15 This contact induces the release of important growth factors (transforming growth factor-beta [TGF-β] and platelet-derived growth factor [PDGF]), whereas coagulants begin the reconstitution process. 25 Coagulation belongs to the first reconstitution stage of the injured tissue, hemostasis. 15 This process results in a deposit of fibrin and other similar substances, which represents a provisional matrix of successive healing events. 15 The growth factors, such as TGF-β and PDGF, are the most important cytokines that initiate the second stage of the skin healing process; namely, inflammation. 26 , 27 PDGF produces the chemotaxis (ie, addressing movements toward a specific stimulus) of other elements of the process, such as neutrophils, macrophages, fibroblasts, and smooth muscle cells. 15 , 27 The first cytokine, in contrast, attracts other macrophages and induces them to secrete further cytokines, controlling the action of the PDGF along with the production/secretion of collagen and of the relevant enzymes degrading the collagen. 15 Within 24 hours of the lesion, inflammation is increased by neutrophils, which enter the lesion and clean it of foreign matter. 15 This action can even last more than a week. 15 The mastocytes, which secrete various substances such as leukotrienes, interleukins, and other enzymes, along with the neutrophils, are responsible for the symptoms of inflammation and vasodilatation: redness, heat, swelling, and pain. 15 Other substances such as monocytes are activated within 2 days. 15 They indicate the beginning of a subsequent overlapping stage; namely, proliferation. Therefore, once the wound has been cleaned, within 8–14 days from the injury, the third healing stage begins, involving the migration of the fibroblasts toward the provisional extracellular matrix made of fibrin and collagen. 15 As this stage proceeds, the release of TGF-β produced by different groups of cells controls the numerous functions of the fibroblasts. 15 , 26 , 27 As the collagen increases (it is important to reinforce the wound), other substances such as the enzymes degrading the collagen decrease. 15 At the beginning, the rate of collagen production exceeds the decrease of other substances. 15 The fibroblasts, which are stimulated by the different growth factors, are divided into myofibroblasts comparable with smooth muscle cells (they hold a protein, which is the alpha smooth muscle actin). 15 , 26 These cells can increase the traction force, and thus they contract and reduce the open area of the lesion. 15 After their contraction, they begin their apoptosis and gradually disappear. 15 The concurrent breaking of the provisional extracellular matrix stops the activity of the fibroblasts. 15 The last healing stage, remodeling, then begins. Remodeling can last for years and depends on the size and nature of the wound. 15 , 27 In this phase, type 3 collagen is replaced by a stronger fiber such as type 1 collagen, but it is lined up without a specific order and is smaller than the collagen of an undamaged skin surface. 15 , 27 This results in more strength but less elasticity. Gradually, as long as the healing process follows a physiological course of action, the scar will lose its erythematous appearance. 15 The healing process undergone by the internal organs, for example, after surgery, is the same as that observed for the skin. 26 , 28 What happens, however, if these processes have been altered? The scar can shift the healing process toward a nonphysiological state, giving origin to a hypertrophic scar (HS), a keloid scar (KS), or an atrophic scar (AS), each one with a different etiology. Scars appear after traumas, surgery, or burns. The HS is, by definition, a healing process increasing in height but always confined to the area of the original wound. 25 A KS not only increases in height but also proliferates beyond the borders of the original lesion. 29 KSs and HSs may represent two different stages of the same disease. 30 , 31 The AS appears as a cutaneous depression. 32 When the dermis and the fascia are affected by scars, these structures are altered, and their function and capacity of interaction with the external and internal environment are lacking. Many are the reasons that provoke such events, from genetic predisposition, to age, but they are still not clearly understood. 29 , 33 At this time, the scientific panorama offers several hypotheses, but the most endorsed is mainly the neuroinflammatory or neurogenic inflammation hypothesis. According to some lines of thought, an excess of neuroinflammatory stimuli and a release of neuropeptides (substance P and peptides that release calcitonin) can be observed, which prolong the production of growth factors and cytokines, generating an extracellular matrix in excess. 30 , 31 The neuroinflammatory overstimulation is probably a result of a reflex arc at the medullary level, which comes from the injury (sensory nerves with nonmyelinated fibers of type C and delta fibers) and then returns as a neuroinflammatory signal, with a consequent excess activity of neuropeptides. 34 Research has confirmed an increase of nerves in the region of scarring, particularly HSs, and an accumulation of neuropeptides. 34 This means a scar can present daily stimuli, enabling us to understand the symptoms we are going to examine later in this article. What generates this inflammatory overstimulation? According to some textbooks, skin-rubbing stimulates a neurogenic inflammatory response, 31 and a tight dress is enough to stimulate a neurogenic reflex arc. According to another current thought, this neuroinflammatory response is mainly caused by stimuli of anomalous tension originated in the injury. 31 , 33 This process provokes a release of neuropeptides from cells native to the extracellular matrix (therefore, not only those belonging to the nerve endings), stimulating an inflammatory reflex arc. 30 , 31 , 35 With reference to this idea, the tension on the injury depends on the direction of the injury itself; for example, in a vertical or horizontal direction compared with the axis of the leg. 36 In fact, in the case of a horizontal scar, there will be a tension three times greater. 37 Tension is certainly a factor predisposing the onset of these problems, but we still do not know whether it initiates a deviation from the physiological healing process of an injury or affects the scar once the healing process has concluded. The force lines recordable in KSs are addressed outside of the scar, with a consequent expansion of the tissue; recent studies have proven that their margins are pulled outward, with considerable peripheral tension, whereas the central area is subject to a mild tension. 30 , 31 It is well-known that KSs and HSs frequently arise in specific sites; namely, the anterior chest, the shoulders (especially the scapular area), the lower abdomen, and the earlobes. 36 Mechanical forces may be perceived by two types of receptors: the mechanoreceptor (or mechanosensor) and the mechanosensitive nociceptor. The first deals with the information of mechanical modifications, whereas the second mostly controls the information of pain. However, both convey somatic information. 36 We can logically assume that in the presence of a scar, these receptors may experience an alteration, resulting in transmitting nonphysiological signals and creating a pathological reflex arc. It is worth remembering that the language of the cell is, precisely, the tension, which activates the mechanotransduction (ie, the chemicobiological and metabolic response to the tension). 35 , 36 , 38 This response will be different depending on how the tension emerges and depending on different parameters. However, it is usually ignored that if the tissue where the tension is observable is in an unbalanced condition, as in the case when a scar is present, the cells cannot properly interpret the message, giving consequent anomalous responses. At this time, one of the reasons explaining the finding of KSs is the constant stretching of injured tissue. 36 , 39 However, the real causes that give rise to a nonphysiological scar are still obscure. With regard to the lymphatic system and its correlation with nonphysiological scars, there is little information found in the medical literature. A difficulty in the lymphatic drainage of the area concerned is presumed, but it is still unknown whether this may cause further damage or not. Deep traumas can also affect the fascia and the viscera, which then go through an identical healing process. The fascia is rich in corpuscles (ie, the Golgi’s, the Pacini’s, and the Ruffini’s corpuscles), with proprioceptive properties and significant peripheral information, as well as with probable nociceptive function. 40 Furthermore, the fascial tissue is made of contractile fibers, which may possibly produce spasms and consequential dysfunction and pain. 40 Via the postsynaptic dorsal column and the spinothalamic tract, the viscera send signals to the spinal cord, which convey information related to pain and to interoceptive alterations. Visceral primary afferents are known to be rich in neuropeptides, such as substance P. This information will be useful in understanding the symptomatology described later. 41 , 42 In conclusion, we emphasize that the percentage of adhesions as a result of surgery rises to 100%. An adhesion is a cicatricial event. 43

One of the most important connections between the skin and the body is that with the sympathetic nervous system. Its efferent fibers stem from the preoptical center of the hypothalamus and then descend to the brainstem and the spinal cord (intermediolateral fasciculus), where they finally join other neurons. 17 , 44 The latter are known as preganglionic neurons, whose axons laterally derive from the medulla and finally reach the sympathetic ganglions. 17 , 44 The preganglionic fibers emerge from the anterior roots and, through the white rami communicantes, reach the paravertebral sympathetic chain. 17 , 44 Sympathetic postganglionic nonmyelinated fibers depart from here (gray rami communicantes) and then come in contact with different peripheral nervous fibers, finally arriving at the various sweat glands. 17 , 44 The sympathetic preganglionic fibers housed between the second and the ninth thoracic segment concern the skin of the superior limbs, the preganglionic fibers located between the first and the fourth thoracic segment concern the face and the eyelids, and the fibers placed between the fourth and the twelfth thoracic segment concern the entire trunk, whereas those situated between the tenth thoracic segment and the third lumbar segment concern the inferior limbs. 17 The cervical tract is related to the acknowledged cervical ganglions, including the stellate ganglion of the last cervical vertebra and the first thoracic vertebra. 17 Therefore, there is a metameric overlap of the sympathetic innervations. The hypothalamic area not only transmits efferents but also receives numerous sensitive afferents; for instance, those deriving from the thermoceptive system (hot and cold receptors of the skin) and the mechanoreceptive system (receptors that participate in the proprioceptive and motor control of the skin stretch pattern), the mechanosensitive nociceptor, or again, those stemming from the trigeminal nuclei (the trigeminal system is also connected to the cerebellum), and finally, from the thalamus. 14 , 17 , 45 – 47 The information is then integrated so as to achieve an adequate thermoregulation (ie, the hematic variation of the skin) or a better endocrine response and postural change (the cerebellum has proven to be stimulated by information from the skin) and further functions. 17 The skin is connected, both in afferent and efferent mode, to the entire body and to all the systems, including emotions. Emotional sweating (also called mental sweating), which is mainly evident in the palms of the hands and feet or in the axillas, partly works independent of the sweating related to thermoregulation. 17 It is controlled at different levels and depends on the central nervous system. With reference to the cortex, the anterior cingulate cortex is chiefly involved in controlling emotional sweating, whereas its dorsal half receives visual sensory information and sends, in turn, information to the brainstem to control the relationship between the eyes and the movements of the head. 17 Recently, research has demonstrated that the skin performs an electrical sympathetic response, depending on the image watched and on the emotion it provokes. 48 Furthermore, it is important to remember that the skin also acts in response to the stimuli of light and that melanocytes directly originate from the central nervous system from an embryological perspective. 7 , 49 However, the electrical response of the skin varies depending on the age of the patient. In fact, in people who are older than 60 years, reactions may have a lower value, even though the information received by the skin is always conveyed through the same means of connection. 17 The same variation also depends on the disease in progress. For example, people who suffer from diabetes or chronic renal failure, or people with disorders related to the central nervous system, have a reduced sympathetic response of the skin. 17 Deep breathing, as well as rapid eye movement, can stimulate a sympathetic response of the skin, which is electrically recordable. 17 The skin can stimulate the sympathetic nervous system, which is connected to the entire nervous system, both efferently and afferently. 50 The fascia has a high density of nerve endings belonging to the sympathetic system, and according to some studies on rats, it could also have a metameric innervation, corresponding to the underlying musculature. 21 However, scientific literature still offers little material on the innervation of the fascia. The electrical activity of the nervous system is not restricted to the mere distribution of electrical efferent impulses toward a sole direction; in fact, nerves convey not only electrical impulses but also chemicobiological, neurotrophic, and at the same time, immune substances. 40 This process, which is not simply an electrical activity, can take place both in afferent and efferent mode, regardless of the nerve’s function. 40 For instance, depending on the nature of the muscular contraction, the contractile tissue synthesizes some neurotrophic molecules (such as neurotrophin 3, neurotrophin 4, brain-derived neurotrophic factor, and so on), which can move along the axis cylinder in retrograde motion until reaching the motoneuron structure to modify its form and, as a result, its function. 40 Therefore, a section of skin affected by a scar transmits, via the sympathetic nervous system, chemicobiological and metabolic information to the medullary neurons and interneurons of the related metameric level; this affects other motoneurons or sensitive neurons at the same level, whether ipsilaterally or controlaterally. 40 The transmission of an electrical impulse to a specific point is easier than the conveyance of a metabolic message to a single neuron. That is why there can be a general symptomatology that is different from the single symptoms observed in a restricted area. 40 When there is a fascial injury, there is a fascial dysfunction. 21 , 40 A physiological alteration in any part of the body will affect, as a result, everything that is covered by the connective sheet: the symptom will arise in the area concerned with the alteration or, in contrast, in a distal area, when this is not capable of adapting to the new stressor. 40 With reference to the symptoms, what happens in the presence of a scar? We present here some clinical case-studies taken from the existing scientific literature and from our professional experience.

The integument is composed of the epidermis and the dermis, which derive from different embryological sheets. The epidermis is the surface epithelium that originates in the ectoderm, meaning it is part of the structures that are in contact with the outside world. 1 , 2 Among the other structures derived from the ectoderm, we identify the central and peripheral nervous system, the pituitary gland, the dental epithelium, and the mammary gland. 3 – 6 Here we can find not only keratinocytes (which represent the first immune barrier, as they act as sentinels) but also melanocytes and immune cells (such as the Langerhans cells and the T-lymphocytes). 7 , 8 There are also tactile cells, which are differentiated for selective touch. 9 The dermis originates in the mesoderm, where, among other things, the connective tissue, bone, cartilage, blood, and their relevant organs are found. 10 – 12 The dermis supports the epidermis and nourishes it. 13 Numerous lymphatic and vascular vessels go through it, as well as different nerve endings, which can be free, as in the epidermis, or encapsulated in complex structures. 9 , 13 , 14 The skin, with its 1.8 m 2 surface, is one of the largest organs of the human body and is the one most exposed to the environment. 13 It is subject to a continual exchange of information, not just tactile but also concerning light and liquids. Therefore, we can reasonably affirm that it is always electrically active. 13 – 15 The skin sends and receives information to the entire body, although with different intensities depending on the location. 16 For instance, the electrical activity of the dermis reflects its sympathetic sudomotor cholinergic function, which brings about continuous changes in the electrical conduction property of the skin, depending on external and internal stimuli. 17 To make another example, the mechanoreceptors of the skin always give information on posture, using low-threshold mechanosensitive afferents. 18 , 19 Therefore, the skin is continuously developing. It is a mistake to think of the cutaneous surface as something unchangeable; on the contrary, it is always changing and directly participates in the homeostasis of the human body. Beneath the dermis, there is an adipose layer, which also derives from the mesoderm. 20 Beneath the adipose layer, we find the so-called fascia. The fascia should be regarded as a connective sheet that covers various areas by perfectly adhering to them like velcro, composed of irregularly arranged collagen fibers that are markedly different from the regularly arranged collagen fibers recognizable in tendons, ligaments, or aponeurotic sheets. 21 The fascia surrounds and connects every muscle, even the tiniest myofibril, bones, nerves, and every single organ, forming a fascial system and bodily continuity. 22 – 24 Embryologically, the fascia derives from the mesoderm, being the continuation of the connective tissue. 24 The fascial system consists of several layers, each characterized by different direction and thickness, which are constantly and jointly communicating and exchanging information. The fascia is the philosophy of the body, meaning each body region is connected to another, whereas osteopathy is the philosophy of medicine: the entire human body must work in harmony.