Insanity might, with some show of reason, be included in this section, as its relation to disease of the brain is so entirely un known. We have already endeavored to point out, in speaking of delirium, the means of its diagnosis, to which it is unnecessary again to allude.
The symptoms of functional disturbance cannot be classified according to the disorders of other organs with which they are associated ; we shall, therefore, take them in the same order adopted in the previous chapter, considering them in their rela tions to intellectual faculties, to sensations, and to power of motion.
Here we meet with neither coma nor delirium ; their counter parts, however, may be traced ; for we have the semi-stupor seen in what is called the hydrencephaloid disease of childhood, the mock hydrocephalus following on exhaustion, either from diar rhoea, from excessive depletion, or from want of nourishment. In carefully following up the rational principles of diagnosis, which it is the object of these pages to elucidate, the error which this very name implies will be easily avoided, because on the one hand the history will teach us that the child has been exposed to - depressing causes, while on the other its actual condition will be defective in some of those characters which are necessarily asso ciated with inflammation of the brain ; as we find, for example, a cool scalp or a depressed fontanelle: when mistakes have been made they have arisen from limited inquiry, and from reasoning upon partial information. Another counterpart to the condition of coma in seVere disease, is seen in the fainting-fit in the adult, which is sometimes simulated by hysteria, but is, in truth, merely an expression of want of blood in the brain. Then, again, corre sponding to hallucinations and illusions, we find ocular spectra and deceptive noises, as well as all the morbid fancies of the hysterical and hypochondriac. More common forms of disturb ance are met with in the complaint of loss of power to carry out an ordinary train of thought, or transient loss of memory.
Among sensations may be reckoned as the most common, head ache and giddiness ; then partial blindness, tingling, ringing in the ears; to these, again, must be added the exaggeration of pain which is produced by constantly thinking of and directing the attention to it.
Muscular spasm and paralysis are not often seen as a conse quence of functional disturbance ; for, although we do not know that chorea is associated with any organic change in the condition of the brain and nerves, it has too much the character of a dis tinct and definite. disease to be classed along with those we are at
present considering: both choreic movements and paralysis are simulated in hysteria. Convulsions, on the other hand, occur in infancy quite as often in consequence of functional disturbance as of organic disease ; among adults we can scarcely include in this class those which are seen in oases of blood-poisoning—ura3mia, and puerperal convulsions—although they be not directly con nected with change in the brain.
In the investigation of " head symptoms" generally, the same rules must be followed as in the more severe diseases of the brain. We have to make out the history of the ease, and the order of sequence of the various phenomena, remembering that, as the attention of the patient is fixed on what he considers the most important symptom, he generally dates the commencement of his illness from the period of its first appearance, and it is only by close inquiry that he can be got to admit any previous derange ment of health; indeed, it may have been so insidious as to escape his observation. Then diligent search must be made for other indications referring to the brain or nerves, besides that of which the patient complains, lest, perchance, it should be discovered that it is but one link in a chain of symptoms which proves the existence of some severe disease of the encephalon.
In the order of examination we shall next be able to exclude febrile and inflammatory states; and then the appearance of the patient in regard to conditions of anaemia or plethora naturally occupies our attention : not indeed in the more marked forms of blood changes, where hemorrhage, purpura, or chlorosis constitute distinct classes of disease, but in such minor deviations from health as perhaps are only testified by the circumstance that the symp toms are either relieved or aggravated by the recumbent posture. Along with this we naturally take the condition of the organs of circulation, when a slight cardiac murmur, unaccompanied by other evidence of disease, may be enough to explain uneasy sen sations in the head, which are far more tormenting to the patient than the dyspnosa or palpitation which we might expect to find, and the very existence of which he utterly ignores.