Remarks ON THE MEANING AND MECHANISM OF VISCERAL PAIN: AS SHOWN BY THE STUDY OF VISCERAL AND OTHER SYMPATHETIC (AUTONOMIC) REFLEXES
Authors: J. Mackenzie
Journal: BMJ (1906)

IN the following study an attempt is made to demonstrate the-principles on which pain and other symptoms of visceral disease are produced.A great many phenomena of which we are cognisant lave never been carefully analysed, but have beexi heed- lessly attributed to some seemingly self-apparent cause.On critical examination it will be found that the phenomena are of a nature totally.different from that usually accepted, and involve a complex mechanism hitherto unsuspected.Many of the observations quoted here may seem trivial and unimportant, but as straws show the direction in which the wind blows, so an appreciation of the true alature of these simple reflexes reveals the meaning of many important clinical symptoms at present overlooked or misunderstood.Ever since 1891, when I found out that definite areas of the skin may become reflexly hyperaesthetic in visceral disease, I have not only used this symptom as an aid to diagnosis, but I have pursued the inquiry into other reflex phenomena.The conclusions arrived at in these papers are not hasty generalizations from a few observations, but are the results of many years' patient study, obser- vation and practical application, and are therefore the natural deductions from a great mass of well authen- ticated facts.If I seem to pay scant attention to the results of other workers in this field of observation, it is not for lack of appreciation of such writers as Hilton, .Ross, and Head, but simply because space prevents me dealing with any matter other than that essential to my argument.A certain parallelism may be found in some of these observations to some of those of Head, but a conclusion is reached different from that he has lately enunciated.From his remarkable researches he has been able to demonstratethat the skin is endowed with two forms of sensibility-an "epicritic" and a "proto- pathic."By means of the former, we perceive the finer ,forms of stimulation as touch, accurate localization, refined.difference in temperature, hnd so forth.The protopathic " sensibility representsa.moreprimitive and -bluntedi form, localization is not so accurate, touch is not perceived, but pa4n is felt on pricking with a pin, the points of the compass are only recognized as distinct when separated by at least 2 cm, the extremes of temperature -only are appreciated.His demonstration of these forms of cutaneous sensibility is convincing;.but when he goes -onto attribute"protopathic" sensibility to the viscera, his conclusions are not borne out by the evidence he produces.When one contrasts the wealth of material he ,gives to demonstrate the protopathic sensibility in the skin with the paucity-nay, with the absence-of facts in favour of his assertion that the viscera are endowed with ,protopathic sensibility, one realizes that some other principle must govern the nerve supply of the viscera..One is driven to this conclusion with the greater force when it is considered thatthe viscera are totally insensi- ive to all the forms of stimulation which Head employs to produce the sensationhe terms "protopathic."So -as his writings show, IHead has not taken into account great many phenomena that throw a flood of light upon this subject, and which, I think, lead logically to a proper -appreciation of the sensations produced by the viscera.Classification of the Symptoms of Visceral Disease.The sym ptoms of visceral disease may be looked upon Aas threefold: (1) Symptoms due to modification of func- tionn; (2) local symptoms due to changes in the organ itself; (3) symptoms which arise through implication the nervous system.It is with the consideration of the reflex nervous symptoms included in this last division that Ithe following study is concerned.3