Specific centres are points within reach from the outside of the body where direct effects can be had on a given group of nerve centers.  Usually they correspond with the location of these centers in the spinal cord, though not always.  Thus the fourth dorsal proves to be a specific center for the vagus nerve; the sciatic nerve proves to be a specific center for the inhibition of menstruation and uterine reflexes generally.

    The reasons why treatment of specific nerve centers has the success that it proves to have in controlling disease processes and in curing disease is a matter for the subject of principles.  Neuropathic lesions do undoubtedly exist, and can unquestionably be controlled or removed entirely by specific treatment.

    As osteopathic experience broadens, it seems to point to a more and more accurate definition of specific nerve centers.  It seems to indicate that the neuropathic treatment to be effective must be applied to the specific centers, and is wasted in so far as it misses these points, which are often not only confined to one particular segment of the cord and column, but to one particular side thereof.  The determination of those centers is matter for principles or for osteopathic practice, or both, rather than for technic.

    In considering the technic of treatment of these centers, the first point is always to secure relaxation of the muscles if contractures are definable around the center.  As a rule, these contractures will themselves indicate the specific centers for any given condition.  But sometimes the contractures are so general that it is impossible through them to locate specific centers; and in rare cases contractures are not found at specific centers at all.

    The first point in the treatment is to secure the relation of these contractures.  This alone, if sufficiently done, constitutes an effective treatment to the neuropathic lesion.  In many cases it is inadvisable to push the treatment to the point of complete relaxation, which is sometimes due to exhaustion, with possibly less effect than would come from less treatment.  Often the neuropathic condition is corrected by less than enough to secure total relaxation of muscles, and on returning to them after some minutes, they are found to have relaxed from that alone.

    From means so simple as this it is hard for minds steeped in the mystery sense of disease to expect results as potent as are actually obtained.  The effect is in reality very powerful.  It is necessary to form some estimate of the powerful effect of such local stimulation on organs connected with the nerve centers stimulated.  This differs by immense degrees in different individuals, but there are certain factors that may serve as general guides until the personal equation of the patient has been determined.

    Racially, the Hebrew race seems to be endowed with a nerve mechanism whose sensory side is extremely developed; possibly from inbreeding.  It seems to be necessary to keep this fact constantly in mind in treating members of that race.  It is certainly not alone the higher nerve centers, but the whole sensory mechanism, organic as well as psychic, that responds with comparatively greater keenness.

    In the English race the sensory nerve mechanism seems to be extremely stable, but there is possibly some relatively greater liability to err in the motor nerve mechanism.

    In children the sensitiveness is in proportion to age.  Children respond with many times as great sensitiveness as mature persons.

    After discounting the general factors so far as they can be determined, one may then study the individual.  People of highly developed literary, musical or artistic faculties usually show greater sensitiveness of the sensory mechanism; which is doubtless the reason why they have become artists.  There is, however, an individual diathesis in practically everyone.  In persons of high sensitiveness treatment should be gentler and more frequent.  In a stable nervous mechanism it may be more prolonged and not so frequent.  In others we find the diathesis to be vaso-motor rather than in sensory or motor nerves.  In others the chief weakness seems to be in the organic activities.  Since these peculiarities will show themselves in the types of disease from which the patient suffers, as well as in the results of treatment, it is not as a rule difficult to discover them, and no especial difference other than the relative strength, duration, and frequency of treatment need concern us.  It is perhaps always wise to make the first treatment or two gentle and to study in them the types of reaction of the nervous system of the patient.

    The power of this specific treatment may be seen from some very simple illustrations.  A sneeze represents a reaction of the sensory mechanism to irritation of the vaso-motor apparatus.  It is imperative and often powerful.  Yet it may be checked in mid career and almost instantly in most persons by simple pressure with the finger in the angle between the nose and the upper lip, or in general on any point in the “pituitary area,” comprising the area between the mouth below, the eyes above, and the malar bones on the outside.

    Hemorrhage of the nose represents either actual traumatism or vaso-motor spasm often of an intense character.  Yet it may be checked in sixty seconds or thereabout by vigorous stimulation of the tissues in the angle between the occiput and the neck, which cause a vaso-constriction with possibly a curling up of the walls of the ruptured vessels sufficient to check the hemorrhage.

    Diarrhoea may be checked by inhibition for twenty or thirty seconds over the second sacral nerves.  I have also seen violent hysteria with intense headache of the vertex and palpitation checked in a few minutes by  inhibition at this point.

    The action of the heart is markedly influenced in a few seconds, sometimes in five seconds or less, by vigorous stimulation at the cartilages of the first ribs; and may be influenced with less promptness from all upper dorsal nerves.

    That this is true not only of motor functions but of secretory functions as well may be shown by pinching the septum of the nose; when in a few seconds a marked increased secretion in the lacrymal glands may be observed.

    In fact, in all functions of the body that may be tested it is found that stimulation has a very powerful effect, immediate in some cases, slow in others, according to the quickness or slowness of the natural functions of the organ.  In the organs that cannot be so tested, it must therefore be assumed that there is an equally powerful and prompt effect.  It is found also that the character of the stimulus applied affects, at least in the first stages of the response, the character of that response.  It is found that different effects are had from different nerve centers; and that for specific effects it is necessary to determine the specific centers for those effects.

    In a recent case treated in my office the patient complaining of cramps in the legs, inhibition and relaxation of the eleventh dorsal nerves caused cessation of that pain, but the nerve overflow appeared in the head, as violent headache.  Similar treatment of the sub-occipital nerves relieved that symptom in a very few minutes, but the pathologic excess then appeared in the vagus nerve, as nausea.  Inhibition of the fourth dorsal nerve drove it from that point to the vaso-motor nerves, and it appeared as chill, goose-flesh, and trembling of the muscles.  Continued treatment of the fourth dorsal drove it from that point, and it then began its wanderings all over again.  Disappearing from one of these points, it seemed to be able to move to one of the others, nor was I able to determine what direction it would next take.  But to drive it from any one place it seemed to be necessary to treat the specific centers involved.  After perhaps thirty minutes of this experience I allowed the patient to rest, and after an hour there was an abatement of the intensity of the pathologic excess.  The source of this pathologic force was finally traced to shock to the endocrin mechanism due to a number of causes—pelvic disorder, pelvic traumatism (operation) lesions at fourth dorsal and twelfth rib, etc.  The point to note here is the prompt and powerful effect obtained by specific treatment.

    When treatment is of an inhibitory character it is possible to estimate the probable effect by its effect on the operator himself.  From continued pressure in spot the nerves of the finger finally become numb, and perhaps tingle.  It is probable that the physiological processes in the patient are very close in time to those in the operator; and the time when numbness begins in the fingers should mark therefore the time when inhibition is effective in the patient’s nerves.

    That there is a practical and real difference between the effects obtained by so-called stimulatory and inhibitory treatment is evident.  The scope of the difference is not great, however, and is applicable to only a few cases.  When it is applicable, however, it is important.  The chief difference is in the immediate effects; the ultimate effects being more and more nearly the same as more time passes.

    The difference is most easily seen in for instance an excited stomach with tendency tot emesis.  Vigorous stimulation to the fourth dorsal nerves on the right side is apt to bring on the emesis immediately; inhibitory treatment to allay it.  Relaxation of the muscular fibres gives a more perfect relief.  The contracture recurs, however, if the condition is due to irritation from the contents of the stomach, which should then be voided.

    Stimulation is obtained also by “getting motion” in the joints of the segment where the specific center is found.  And getting motion here means stretching the tissues of the joint with more or less force at the limit of their normal motion.  This is in effect stretching also of contracted areolar and ligmentous tissue, which usually participates in the contracture, particularly if the case is of long standing.  In some cases such vigorous stimulation as this—and it is possibly the most  vigorous of all the available methods—is necessary to secure sufficient reaction to overcome the deadlock in the nerves.

    Vibration and electricity are as a rule contra-indicated.  The effect of both is to cause fibrous deposits and interstitial hardening.

    The first  effect of stimulation is on sensory nerves connected with that segment; more prolonged stimulus reaches motor nerves; vaso-motor effects are then observed, in turn; while if effect is desired on organic functions, particularly the more remote organs of internal secretion, it requires much more prolonged effort.

    Treatment to nerve centers and to soft tissue generally is a thing that for its best adjustment and success must be guided by an intelligent and vital sympathy with the nervous state of the patient, by judgment of individual cases, by experience.  Insofar as it can be discussed scientifically it is subject to the same laws that govern the disease process generally.  The disease process is the reaction of nature to irritation or injury or abuse that has overwhelmed its normal equilibrium.  All such stimuli, as all stimuli of whatever character that affect the body, are absorbed by the sensory nerves and transmitted to the higher centers of the nervous system.  When they are in excess, they follow a different route from that followed if they are within the normal range.

    Their normal route is to pass at once to the higher brain, over nerve tracts each of which is more sensitive than the one below, as we approach the highest ; there they area co-ordinated with all of the messages arriving at the time, in agreement with the accumulated wisdom of the individual.

    Each higher relay of nerves is, as we said, more sensitive than the ones below.  Now excess of stimulation becomes irritation, and irritation causes, as everywhere in life, the withdrawal of the part irritated.  When irritation reaches these sensitive higher nerves, they withdraw form the co-ordination.  These higher nerves are more sensitive, and a degree of stimulation that is not too strong for lower tracts becomes too strong for the higher ones.  Picture then a stimulation slowly growing in tensity.  There comes a point when it becomes irritation to these higher nerves, and they withdraw.  The irritation has then to overflow into the motor nerves without the co-ordination of these higher nerves—as if it were short-circuits, and reaches the motor nerves at a lower level and in more intense form.  We have therefore from this slowly growing irritation first intense mental reflexes, as a short temper; then physical pain; then involuntary motor spasm, focal at the nerve centers that govern the part affected; then vaso-motor spasm, or inflammation, in its increasing stages of severity.

    The effect of stimulation to specific centers is first of all the same as the effect of any new stimulus; it causes a suspension of existing co-ordinations until they have taken cognizance of the new one—it acts as an inhibition until the new stimulus has been co-ordinated.  Re-co-ordination is just what is called for in a neuropathic lesion.  A new stimulus sufficient to break up the existing deadlock of the nerves allows the normalizing tendencies of the whole body to assert themselves.  It matters nothing what is the stage of this slowly developing process, the effect is still to cause a re-co-ordination toward the normal.  This effect is first on the higher or sensory co-ordinations, and reaches the greater depths of false co-ordination with more persistent treatment.  It seems to be the case that a lighter treatment, an inhibitory form of treatment, is best for sensory disorders; an active relaxation seems to be necessary for motor disorders; a vigorous stimulation for control of vaso-motor spasms; and a more prolonged and deeper stimulation to reach the trophic functions.  In diseases of long standing, chronic diseases, the same general principle holds true—it takes longer in proportion to the age of the disease.  On the average it is said to take a month for every year that the affection has continued; though this does not hold always, for I have seen troubles of ten years standing relieved at one treatment, and I have also seen diseases of a few weeks standing resist stubbornly for months.  But “You have to keep on feeding a calf to make it fat,” says Dr. Still.

    Too severe a treatment will often confine the effect to the immediate locality and lose all general effect.  Certain tissues are in particular sensitive in this way, notably the eye.  Local treatment to the tissues about the eye must bee very carefully guarded.  The palate, tonsil and Eustachian tube are also very sensitive, a provision of nature to guard the entrance to the alimentary tract and the lung; and direct treatment should be given very carefully.  The abdomen generally is subject to the same rule.  In such diseases as asthma and hay fever the whole nervous system requires to be handled carefully.

    A wise rule is never to push a treatment as far as it can be pushed at one time, but to stop as soon as a definite reaction has been secured; unless the condition is one of emergency.