(3) The coma may be uræmic. In some cases anasarca and slow pulse point at once to this pathological condition. In all comatose cases without history the urine should be drawn with a catheter for testing, and signs of various forms of Bright's disease may be detected. The ophthalmoscope (easily used in comatose subjects) may yield most valuable indications by revealing retinitis albuminurica or neuro-retinitis.
(4) The patient may be under the effects of a clot in the brain or of acute softening of a considerable part of the organ. Hemiplegia with conjugate deviation of the eyes and head is usually present, the head and eyes turning away from the paralyzed side, the patient looking, as it were, toward the lesion. A latent hemiplegic state may sometimes be determined by one-sided redness of the buttock, and by a slight difference of temperature between the two hands (paralyzed side warmer). The general temperature of the body (measured preferably in the vagina or rectum) exhibits a marked rise. After cerebral hemorrhage there is, according to Charcot and Bourneville, a fall below the normal during the first hour, followed by a steady rise to 106° or 108° F. at death in severe cases. After embolism or thrombosis, causing softening, the rise of temperature is less in extent and not as regularly progressive.
(5) The subject may be simply drunk or poisoned by alcohol. In such a case the patient may usually be roused momentarily by loud speaking, shaking, or by painful impression; the breath is alcoholic; the cerebral temperature subnormal or normal. The urine must be tested for alcohol.2 It must not be forgotten that on the one hand intoxicated persons are most prone to falls causing fracture of the skull or concussion, and on the other hand that the early stage of coma from meningeal hemorrhage resembles narcosis.
2 Anstie's Test.—A test solution is made by dissolving one part of bichromate of potassium in three hundred parts by weight of strong sulphuric acid. The urine is to be added drop by drop to the solution. If a bright emerald-green color suddenly results from this manipulation, it signifies that there is a toxic amount of alcohol in the urine.
(6) The coma of congestive or malignant malarial fever is to be distinguished mainly by the absence of physical or paralytic symptoms, coinciding with a high rectal temperature. The spleen is often enlarged. Some would add that Bacillus malariæ and pigment might be found in the splenic blood, withdrawn by a long, fine needle.
(7) Toxic narcosis, from opiates, morphia, chloral, etc., are often difficult of diagnosis, except that from opiates and morphia, in which extremely slow respiration and contracted pupils, with lowered temperature, point at once to the cause.
In studying cases of coma all the above-enumerated symptoms should be considered as of great negative or positive value: often the diagnosis is only made by exclusion. The Cheyne-Stokes respiration, pupillary variations, differences in pulse-rate and volume, are present in such varied conditions, irrespective of the nature of the lesion, as to render them of minor value in differential diagnosis.
DOUBLE CONSIOUSNESS is a rare condition, in which the subject appears to have separate forms or phases of consciousness, one normal, the other morbid. This occurs in hypnotic and somnambulic states, probably also in certain cases of insanity and epilepsy. The current of normal consciousness is suddenly broken; the patient enters into the second or abnormal state, in which he acts, writes, speaks, moves about with seeming consciousness; but after a variable time a return to normal consciousness reveals a break in the continuity of the memory: the patient has no recollection whatever of what he did or said in the morbid period. In the hypnotic state subjects may show increased power of perception, and are strangely susceptible to suggestions or guidance by the experimenter. In a second attack the patient often refers back to the first, and does things in continuation or repetition of what he previously did, apparently taking up the same line of thought and action. The morbid states, long or short, are joined together by memory, but are wholly unknown in the normally conscious states. In other words, the patient leads two (or three, according to a few observations) separate lives, each one forming a chain of interrupted conscious states. In epilepsy we observe remarkable breaks in normal consciousness: the patient goes through certain acts or walks a distance or commits a crime in a dream-like state, and suddenly, after the lapse of a few minutes, hours, or days, becomes normally conscious and has no recollection of what he did with such apparent system and purpose during the seizure. It might, perhaps, be as well to classify these phenomena under the head of amnesia. A case is on record where a man travelled, seeming normal to fellow-travellers, from Paris to India, and who was immensely astonished on coming to himself (return to common consciousness) in Calcutta. Many murders have been committed with apparent design and with skill by epileptics, who upon awaking from their dream-like state were inexpressibly horrified to hear of their misdeeds.
AMNESIA, or loss of memory, may vary in degree from the occasional failure to remember which is allowed as normal, to the absolute extinction of all mental impressions or pictures. This word and the expression memory are here used in a restricted sense, reference being had only to purely intellectual and sensorial acts related to intellection. If we take the general or biological sense of the term memory as meaning the retention of all kinds of residua from centripetal impressions and of motor centrifugal impulses, including common sensory and visual impressions, special sense impressions, all unconsciously received impressions, emotional, intellectual, and motor residua, we should consider amnesia in a correspondingly general way. This, however proper for a physiological study, would be far too complex and premature for an introduction to practical medicine. Recognizing memory, therefore, as a universal organic attribute—a capacity to retain impressions—we will treat of it only in the commonly-accepted sense referred to supra.
Failure of memory may be real or apparent. In the latter sense amnesia is induced by diversion of the attention into a channel different from that in which the line of inquiry is conducted. A normal example of this is seen in the state known as preoccupation, where a person intent upon a certain thought or action forgets who is about him, where he is, and if asked questions fails to answer or answers incorrectly. In pathological states, as in acute curable insanity, apparent loss of memory is often caused by the domination of an emotion or of delusions. In both cases, if the subject can be roused or brought to himself, he remembers all that we inquire about and is amused at his previous false answers or silence. Real amnesia consists in the actual blotting out of recollections or residua in a partial or general manner, for a time or permanently. These differences serve as the basis of a complicated subdivision of amnesia which it is not necessary to fully reproduce here.