Purpura is likewise, at least for the most part, merely symptomatic, appearing in the later stages of malig nant fever, more especially in those where the compo nent parts of the body seem to have a tendency to de composition. Some cases, however, have occurred, where Purpura has existed without a proportionable degree of the febrile state, or indeed where this has been altogether absent, but they are involved in con siderable obscurity ; and we have little certain infor mation respecting either their nature, or their imme diate exciting cause. The same uncertainty also re gards the cure of the idiopathic Purpura ; for while we are told from high authority, that it is relieved by to nics, and especially by the mineral acids, we have equally respectable evidence in favour of blood-letting. Fortunately the disease is of rare occurrence, and there fore whatever regards either its cause or its cure, may he considered more in the light of a question of curious speculation, than of any great practical utility.
'We now come to the Neuroses, the second great class of diseases—those depending upon a primary affection of the nervous system. As the phenomena of sensibi lity are more peculiar, and more unlike the other func tions of matter, than even those of the muscular fibre, so its morbid affections are proportionally singular and difficult both to comprehend and to describe. The connexion which the different parts of the nervous sys tern bear to each other, is one of its most remarkable properties, and it is exhibited in a variety of striking examples in its morbid states. We can generally assign to each of the Parhxmasim its primary seat, either by means of our sensations, or of some visible change which the part experiences, but in the Neuroses, we have neither of these circumstances to direct us; there is frequently no visible alteration in the structure of the part affected, while our feelings afford but little assist ance in informing us of the original situation of the disease. The circumstance which must chiefly direct us in our arrangement of this class, is the degree in which the power exists, whether it be morbidly in creased, or morbidly diminished, with relation to the standard of health ; to this we have added another di vision of actions, which are simply irregular, without any regard to the mere quantity of effect produced. These three orders we have denominated, respectively, Erethismi, Asthenix, and Spasmi.
We have divided the order Ercthismus into the two genera of Hyperxsthesix and Autalgix ; the first con sisting in increased nervous sensibility, as manifested 1,v the inordinate action of the external senses, or of the or ganic functions; the latter comprehending those diseases where there is pain in any organ, which, so far as we can judge, depends merely upon a nervous affection of the part. The diseases which seem to belong to the order Erethistnus, and to the genus Hyperxsthesia, in particular, are many of them evidently symptomatic, or connected with some other disease, which is the principal object of our attention ; yet occasionally, un der these circumstances, the state of the nervous sys tem itself becomes necessarily the main point towards which we are to direct our efforts. Thus, one of the most distressing effects in fever is want of sleep, and after we have removed the proximate cause of the dis ease, this sometimes still continues, and, by its harass ing effects, prevents the complete re-establishment of the health. The same remarks apply to all those al lions which consist in increased sensibility of the organs of sense, such as a morbidly acute state of the sight, the hearing, &c. or increased sensibility in parts that serve for the exercise of the organic functions, as the stomach and the kidney. For the most part we find
them connected with some more general affection, which chiefly claims our notice, although, as we remarked above, they sometimes become the immediate objects of attention under these circumstances ; and we must also bear in mind, that there are cases in which they indi cate some local affection of the part or organ in which, although symptomatic, they are important, as indicating the existence of the primary affection, or assisting us in ascertaining its nature. Thus, a morbid increase of appetite, which is denominated Bulimia, is sometimes merely a symptom of Diabetes, and can in no degree be relieved by any palliative remedy ; while at other times it originates from a disease of the stomach itself, which may be either structural or functional, and will of course acquire its appropriate mode of treatment. In the rapid sketch of the practice of medicine which we propose to offer to our readers, it will not be in our power, nor would it accord with our plan, to examine each of these affections in detail.
With respect to the method of proceeding in their management, the first point is, to ascertain how far the disease is primary or symptomatic ; if primary, whether it depends upon a local cause of a mechanical nature, upon a visible alteration of structure, or upon an ef fect which operates through the medium of the system at large. If they are symptomatic, we inquire whether we are able to remove them by removing the primary disease, or by remedies appropriated to the removal of the nervous affection itself. It is not easy to lay down any general principles of treatment in a class of affec tions, which are so various in their origin, and depend upon such a diversity of causes. There is scarcely any condition of the system by which they may not be ex cited ; and with respect to individual symptoms, they bear so little relation to their cause, that our judgment must be formed more from the general history of the case, and from a number of circumstances connected with it, than from any train of morbid actions which can be detailed, as constituting the essential character of the disease. The opposite states of plethora and in anition, of excitement, and of quiescence, sometimes pro duce what appears to be the same complaint, and must of course be combated in the individual cases, at one time by depletion and by sedatives, and at another by nutrients and stimulants. Generally speaking, how ever, we think that the modern practitioners have lean ed too much to the latter class of remedies, biassed by their lippothesis of debility, which they have applied with so little discrimination to such a variety of dis eases, and anxious to avoid the errors of the older wri ters, who ascribed nervous complaints to the affections of a subtile fluid, the existence of which they unfortu nately neglected to ascertain before they assumed it as the basis of their pathology. We shall farther remark, that what are styled nervous diseases are, much more frequently than is commonly supposed, symptomatic of derangements of the digestive organs. Some remark able examples of the effect which peculiar states of the alimentary canal produce upon the brain and nerves, are generally known ; of which one of the most import ant is Hydrocephalus, and we are daily accumulating ex perience of the same kind, with respect to Epilepsy and various kinds of convulsions, when not proceeding from local or structural causes. Purgatives will therefore be always indicated in the Hypermsthesix, if not by the immediate symptoms, at least as a means which is to be always tried, even although we proceed entirely upon empirical grounds.