The Role of the Visual System in Posturology

The Role of the Visual System in Posturology

Summary

It is CORRECT that an Optometrist/Orthoptist also takes an interest in Posture. That a Physiotherapist also takes an interest in Posture. That a Vestibular specialist, an Osteopath, a Dentist, a Podiatrist also take an interest in Posture. It is CORRECT AND DESIRABLE to increasingly create complementarity by seeking to join multidisciplinary teams.

It is ESSENTIAL to try to get to the primary cause of the subject's "postural disorder", if possible. This work seeks a path in this direction.

The afferences that we now know affect tonic-postural and visual control relative to the environment are represented by: a) labyrinthine signals from the semicircular canals and maculae, but especially those utricular and saccular (posterior labyrinth) (Gagey,1997). The function of the posterior labyrinth can be summarized in the following three elements: 

1) information on the position of the head in space via a vestibulo-cortical pathway, whose course is not fully known (Villeneuve,1991); 

2) correct distribution of antigravity muscle tone (Magnus,1926) via the vestibulo-spinal pathway; 

3) a) reflex control of eye movements via the medial longitudinal fasciculus; 

     b) retinal, foveal and peripheral signals; "The queen of the information means is sight" (Ricciardi,1998)

     c) proprioceptive signals from the deep cervical and extrinsic eye muscles (Ughio,1980), from the joint receptors of the limbs and spine as a whole, from neuromuscular spindles and Golgi, fascial and tendon receptors; 

    d) signals from tactile receptors in the soles of the feet;

    e) auditory signals;

    f) cutaneous signals; 

    g) signals from the cranio-occluso-mandibular system (Nahmani L.1991).

The various afferences are subject to the control of the cerebellum (vermis) and cortical and subcortical centers; thus originate the vestibulo-spinal and reticulo-spinal reflexes. Voluntary control of postural set uses the pyramidal tract (Schieroni,1983).

From a simple mechanical interpretative model, in which the body assumes the possible attitude depending on the force of gravity mainly as a result of vestibular and cervico-spinal reflexes, we have now reached a systemic-cybernetic theoretical reference model in which man is seen as a system in continuous dynamic interrelation both with the external environment and the internal environment, through incessant information exchange.

The human being is therefore in continuous fluctuation between change and stability.

On the one hand, it tends towards an external goal, which can be reached thanks to control and regulation of the enormous degree of behavioural freedom, both motor and linguistic. On the other hand, it tends towards the maintenance of internal homeostasis.

The way of being and the characteristics of the relationship that the person has with the outside world and his internal microcosm depend partly on fixed and unmodifiable hereditary factors (both physical and temperamental (Le Senne,1960), the ancient Chinese yuan) and partly on modifiable factors, such as the increasingly frequent exposure to adverse conditions, the way of breathing, eating habits, workplace ergonomics, sedentariness or excessive athleticism, psychological attitude and stress, inner and family health (including sexual activity) and many others.

Posture is therefore increasingly identified as the adaptive attitude that the body (and mind) assumes, it is our way of relating to the environment, it is communication.

Consequently, "postural disorder" translates first of all into a condition of general and local stress and fatigue, and secondly, into wear and degenerative phenomena destined to then configure frankly pathological situations.

When equilibrium conditions fail, the body wastes energy throughout the day to manage posture: this is the cause of "postural fatigue". It may simply derive from axial misalignment or from a

complex series of compensations that are morphologically expressed in a postural disorder. The more intense the disorder, and the more numerous the apparatuses and

components of the human body under stress, the greater the postural fatigue. Every postural failure and every deviation from the norm induces structural alterations and deformations: it causes overloads and tensions with gradual wear of the tissues (Lazzari,1993).

In the adaptation scheme to the various environmental stresses seeking to obey the fundamental laws of Equilibrium (in the parietal, visceral, hemodynamic, hormonal, neurological dimensions), Economy (less energy expenditure) and Comfort (absence of pain and/or well-being), priority is given to the latter: man is ready to do anything not to suffer. He struggles, deforms, reduces his mobility, just enough so that these less economical defensive adaptations allow him to regain comfort (well-being) (Busquet,1983).

In assessing the degree of adaptation of the various posture subsystems, in addition to numerous clinical tests, instrumental examinations such as Stabilometry/Posturometry and Behavioral Visual Analysis are also used.

Through Stabilometry, which is the computerized analysis of postural oscillations of a subject during a Romberg test (Guidetti,1989), conditions of balance are evaluated by analysing the position and oscillations of the center of pressure

(projection on the ground of the barycenter) both generally (Franchignoni F.P.,1988) and of each foot, in a predetermined time.

Through Posturometric Examination, which is the physiological evaluative continuation of Stabilometry, the load forces on the three support pillars of each foot in an orthostatic position are detected, analysing their distribution and variation in real time and with variables designed to suspend one or more related control systems, as also happens during Stabilometry: eyes open/eyes closed, with bite/without bite, with glasses/without glasses, with head hyperextension/without hyperextension, with insoles/without insoles etc.

From a morphological-structural point of view in relation to Stabilometry we can find:

1) both the general pressure center and that of the feet are in the correct position; the person is perfectly balanced. But two conditions can occur: the loads are regular or not, but balanced to the effects of balance.

2) The general pressure center is in the correct position and the two foot centers are in the wrong position. It follows that the general balance is good while the balance on each of the two feet is not: the Structure is disharmonious.

3) The centers are all in the wrong position: we are in the presence of a total disorder of balance and a total imbalance of the Structure.

In relation to Posturometry we can find: 

1)    All values are equal; the distribution of loads is correct (ideal situation not easily found); also the pressure centers will be in the normal position. 

         The supporting Structure of the overlying body will be well aligned and harmonious. 

2)    Loads are different:

-    they compensate each other to give as product a correct position of the pressure center: the Structure is disordered, the Balance normal

-    they are in total disorder and the positions of the pressure centers are also incorrect: the Structure is disordered, the Balance is compromised (Lazzari,1993).

It is therefore essential to analyse the Posturometric Examination in relation to the Stabilometric one because variations that do not appear in one may be evident in the other.

The evolution of the process of functional deterioration of the Visual System, with a tendency to Myopization, Esophorization and deterioration related to the Break and Recovery values, is analysed through Behavioral Visual Analysis (Roncagli,1996).

Through various standardized situations characterizing its 21 tests, Visual Analysis aims to modify the input with the intent to evaluate, with a psychometric interpretation, the response of the visual system, i.e. the output, thus allowing information to be obtained on both the state and the evolutionary direction of the visual problem. This protocol manages to inform us not only about the refractive state and visual balance but also about the quality of accommodative and fusional responses.

It is interpreted as the result and not as the cause of the symptoms, discomfort and difficulties shown by the individual.

Emphasizing that the anamnesis represents a fundamental step in the diagnostic process, after analysing the postural attitude of the subject in an upright position both in the frontal and sagittal planes (anterior/posterior type, Barré vertical, podogram) the mobility, muscle tone-trophism and sensitivity of the various segments, the presence of scars are then assessed.

Remembering that the content (eye and muscles) also depends on the container (orbit) and that it is composed of seven bones in continuity with the dura mater, on the osteopathic plane four orifices are important :

-    the optic foramen where the optic nerve and ophthalmic artery pass -    the lacrimal canal -    the sphenoidal fissure where cranial nerves III IV VI pass -    the sphenomaxillary fissure where the orbital branch of the superior maxillary nerve and

the infraorbital artery and vein pass. The alternating movements at the rate of 10-14 per minute of Cranial Respiration allow

pumping and drainage of the orbital cavity and a fluid dynamic in the sinus of the intra-orbital components (Caporossi,1993): the search for torsions, vertical strains and side bending rotations is desirable.

The role of the various apparatuses involved in posture regulation, which is probably destined to increase also in relation to new knowledge on the plasticity of the Nervous System (Aglioti,1999), obliges us to learn not only clinical tests specific to medical specialties historically dealing with balance and posture, such as those used in Neurology and ENT, but also some clinical tests used in Ophthalmology, Physical Medicine and Rehabilitation, Osteopathy, Dentistry.

Clinical tests are then performed:

-    the finger deviation test

-    the indication test

-    the Romberg test

-    the star walking test

-    the Fukuda Stepping Test.

Fundamental importance lies in the study of the patient's physiological eye movements, namely:

-    labyrinthine nystagmus

-    optokinetic nystagmus

-    pursuit movements

-    saccadic movements

-        ductions

-    vergences.

Indispensable are:

-    the podalic convergence test or the rotator test

-    the thumb test

-    the Accommodative/Vergence Flexibility Test

-    the Focus Flexibility Test

-    the Fusion Flexibility Test

-    and others (PPC, Cover, Brock String Test etc.).

Many of these tests can be performed both in different postural situations (standing, sitting) and with exclusion or stimulation of single or multiple apparatuses (OA/OC, with thickness/without, OC head retroversion/OC without head retroversion etc.).

When it is understood that the patient's postural problem is essentially caused by incorrect information coming from a single system, our therapeutic response is straightforward: to a 27-year-old university student who presented to my Physiotherapy clinic complaining for many months of cervical symptoms with infrascapular radiation and proximal visual stress symptoms with burning eyes and fatigue and who presented:

Romberg quotient just above 1, positive postural tests carried out involving the Visual System. Type B2-6 Non Embedded, high Nets but low MSDA, low Focus Test and Fusion Test

The proposed "Physiotherapy" was to advise him to use correct postural attitudes during study and the use of +0.50 for near vision.

After less than a month the symptoms had completely disappeared.

Things get complicated if we find that several systems are simultaneously involved. What do we do? Do we go by trial or by exclusion? Do we look mainly in our own field of expertise since the patient came to us?

The alternatives are two:

- The patient is made to wander among various specialists: the Podiatrist for plantar problems, the Ophthalmologist to prescribe a prism, the Osteopath or Physiotherapist for structural problems, the Orthodontist for the bite (Gagey,1997), the Banker to get a mortgage. 

- Therapeutic conducts are implemented that can culturally be inserted in the integrated vision of the phenomena that surround us and concern us typical of tradition (Mazzucchelli,1991).

This approach has always suggested a way of approaching disease based on three fundamental principles. 

First principle: since each individual is unique, it is necessary to treat patients and not diseases. Furthermore, since the individual is inseparable from the environment, he must be treated according to the context.

Second principle: since each individual is indivisible, every treatment must be global, taking into account all the elements of an affection, allowing to highlight the consequence and cause of a lesion. Hence by extension

Third principle: every treatment can and must go from the symptom to the cause of the disease. Global Postural Re-education (Souchard Ph.E.1983) and Behavioral Visual Re-education can be culturally inserted in the tradition, together with Homeopathy and Bioenergetics. Managing to amalgamate the knowledge of Postural

and Visual re-education in a single rehabilitative, therapeutic and preventive approach is the challenge of tomorrow, now near.

Author

Mazzucchelli Cosimo Carlo Rehabilitation Therapist/Physiotherapist, University of Parma, 1979 Diploma in Global Postural Re-education at UILPTM Université Internationale permanente de thérapie manuèlle (France), 1983 Diploma in Articular Normalizations at UILPTM (France), 1986 Advanced in Visual Training, State University of New York (USA), 2000 Member EASV European Academy of Sports Vision (Italy)

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