A second case recorded by Dr. Watson oc curred in the practice of the late Dr. Sweatman. The patient was a little boy twO years old ; his head bad been gradually increasing from the age of six months until it had become so large as to prevent the child froin continuing long in the upright posture. The boy was active and lively although thin. He never had any con vulsion, but occasionally seemed uneasy, and then would relieve himself by laying his head upon a chair. Ile had never squinted, nor was he subject to drowsiness or startings during sleep, and his pupils contracted naturally. His appetite was good, and all the animal functions were properly performed. The head measured frorn ear to ear twelve inches, from the super ciliary ridges to the occipital thirteen inches, and in circumference twenty-one inches. The brain was sound. The convolutions were dis tinct and retained their shape. The surfaces of the medullary matter, exposed by different sections, presented very unusual vascularity.* In this case the yielding of the cranial walls prevented compression of the brain, whilst it admitted of the growth of the organ within. Bence, no doubt, the absence of any symptoms of compressed or irritated brain.
IIypertrophy of the brain sometimes coexists with hydrocephalus, and is congenital, and prevents by the great size of the org,an the de velopement of the cranial bones. (Otto, Ito kitansky.) Hypertrophy may affect only particular parts of the brain, as the optic thalami, the pons, and the medulla oblongata, instances of which have been placed on record.
Atrophy of the brain.—At the advanced periods of life we generally meet with more or less of %vesting of the brain, resulting from a change in the nutrition of that organ which it experiences in common with all other organs, and which is only the natural result of the pro gress of age. It is remarkable, however, hovr ' much more of this senile atrophy is observed in ( some individuals than in others.
In cases of epilepsy of long standing I have invariably noticed wasting of the brain, affect ing chiefly the convolutions, or sometimes the corpora striata, optic thalami, &c. The brain wastes likewise in cases of long-continued intemperance, the patient generally dying of delirium tremens. In such instances all parts of the brain waste, but the convolutions expe rience the most marked change.
The following are the marks of an atrophied state of brain. There is a considerable quantity of fluid in the subarachnoid cavity, indicating an increase in the interval between the surface of the brain and the interior of the skull. The brain has a shrunk appearance. Its t feels firm, and in cutting the knife grates it as in cutting cartilage. In point of the grey matter is frequently extremely pa and scarcely to be distinguished from the ad. cent white substance; in some instances, how ever, it is of a dark brownish hue. In all cases the layer of grey matter which covers the convolution is much less deep than is natural.
The convolutions are evidently shrunk, and the sulci between them have g,reatly increased in width. The white substance of the brain has increased in density, and in the transverse section several vessels are cut across, the sec tion of which occasions numerous bloody points upon the surface of the centrum ovale. The corpora striata, optic thalami, pons, and medulla oblong,ata are all obviously shrunk and firm in consistence.
In several instances of persons long bed ridden, I have noticed a shrunk state of the cerebellum, with or without atrophy of the cerebrum. The layers of white matter in the cerebellar laminw look particularly small ; and in the section the white layer seems to shrink in within the fold of grey matter in which it is involved.
As a constant accompaniment of the wasted brain, we find a rnore or less opaque condition of the arachnoid membrane, with considerably enlarged Pacchionian bodies. The ventricles of the brain, too, are generally wide and con tain a good deal of fluid. There is also very frequently a diseased state of arteries, atheroma tons or ossific deposits being scattered freely amongst those, which form the circle of Willis, and their principal blanches.
Atrophy of particular parts of the brain is of not unfrequent occurrence, either in cases where particular nerves are atrophied, as the optic nerve, inducing atrophy of the opposite optic tract or of that of the same side, and of the quadrigeminal bodies on the side of the wasted tract ; or where from previous disease of a por tion of the brain the remainder of that part has wasted—as wasting of the corpus striatum from the previous existence of a small clot in it, or of a red softening.
Softening. — One of the most common changes of structure in the brain is softening. This is of two kinds, namely, white softening, or that without discoloration, and red softening, or that vvith discoloration.
White sof tening.—The anatomical characters of the true white softening may be thus de scribed. The diseased portion has diminished considerably in its consistence ; if it be gently rubbed with the edge of a knife it becomes obviously disturbed by an amount of friction which would produce no change upon the sur face of a healthy brain ; a strearn of water di rected upon it, even with slight force, is suffi cient to break it up and separate as well as rupture its constituent fibres, while a similar stream directed against a neighbouring healthy portion produces little or no effect upon it. When examined by the microscope, its consti tuent fibres appear to have undergone no change but that of consistence; they exhibit vari cosities, more numerous than usual, nor can any products of inflammation, or any other ab normal material, be detected among them. The bloodvessels are empty and pale. The colour is very commonly that of cream, sometimes a little more yellow.