A system of practical medicine. By American authors. Vol. 5

by Unknown

XII. Crura cerebri (3 cases).

XIII. Middle region of base of brain and floor of skull (7 cases).—In the main, from optic chiasm backward to pons, in the middle basilar region, in some instances extending beyond this area in special directions.

Tumors of the antero-frontal regions can be diagnosticated with considerable certainty, partly by a study of the actual symptoms observed and partly by a process of exclusion. Headache of the usual type, vertigo, choked discs, inflammatory and trophic affections of the eyes, widely varying body-temperature, and high head-temperature are among the most positive manifestations. Mental slowness and uncertainty seem to be greater in these cases than in others. Mental disturbance of a peculiar character unquestionably occurs in cases of tumor, as of other lesions, in this region. This disturbance is exhibited chiefly in some peculiarity of character, showing want of control or want of attention. The speech-defects present in a number of cases were rather due to the change in mental condition than to any involvement of speech-centres. Under Symptomatology has been given in some detail a study of the psychical condition in one case of antero-frontal tumor. The absence of true paralysis and of anæsthesia is characteristic. Nystagmus and spasm in the muscles of the neck and forearm were present in one instance, but usually marked spasm is not to be expected. Vomiting is less frequent than in tumors situated farther back. Facial and other forms of paresis occasionally are present, but are not marked, and are probably due to involvement by pressure or destruction of surrounding tissue of neighboring motor areas. Hemianopsia, such as was observed in Case 10, showed involvement of the orbital region. Tumors of the inferior antero-frontal lobe give the same positive and negative characteristics as those of the superior frontal region, with the involvement in addition of smell and certain special ocular symptoms, such as hemianopsia.

Tumors of the motor zone of the cerebral cortex, the region surrounding and extending for some distance on each side of the fissure of Rolando, can be diagnosticated with great positiveness: 15 of the 100 cases are examples of tumors of this region, and in many of these the diagnosis of the location of the growth was accurately made during life. Localized spasm in peripheral muscles; localized peripheral paralysis; neuro-retinitis or choked discs; headache; pain elicited or increased by percussion of the head near the seat of the tumor; and elevated temperature of the head, particularly in the region corresponding to the position of the growth,—are the prominent indications. The spasmodic symptoms usually precede the paralysis in these cases. The spasm is often local, and generally begins in the same part in different attacks—in the fingers or toes or face of one side.

A study of cases of tumor localized to the cortical motor area will show that in almost any case a local twitching convulsion preceded the development of paresis or paralysis. Hughlings-Jackson⁴¹ reports a case of sarcoma, a hard osseous mass on the right side of the head, of eighteen years' standing, subjacent to which was a tumor the size of a small orange growing from the dura mater. The patient was a woman aged forty-nine, whose symptoms were very severe headache and double optic neuritis, with paresis in left leg, followed by slighter paresis in left arm and left face. A very slow, gradual hemiplegia came on by pressure on the cortex without any fit. Jackson says this is the only case which he has seen in which the hemiplegia has not followed a convulsion where the lesion has been on the surface. In all very slowly oncoming hemiplegias which he has seen, except this one, the tumor was in the motor tract.

⁴¹ Medical Times and Gazette, London, 1874, vol. i. 152.

As the white matter of the centrum ovale and capsules represents simply tracts connecting cerebral centres with lower levels of the nervous system, with each other, or with the opposite hemisphere, lesions of this portion of the cerebrum will closely resemble those cortical lesions to which the tracts are related. We have already referred to the peculiar symptoms referable to involvement of commissural and association fibres. Tumors of the centrum ovale of the fronto-parietal region, of which five examples are reported in the table, vary in symptomatology according to their exact location. Those situated in the white matter in close proximity to the ascending convolutions give symptoms closely resembling those which result from lesions of the adjoining cortical motor centres. In the cases of Osler, Seguin, and Pick (Cases 26, 27, 28, 29) spastic symptoms in the limbs of one side of the body, with or without loss of consciousness, were marked symptoms. In two of these cases some paresis preceded the occurrence of the spasms. They did not, however, fully bear out the idea of Jackson that the hemiparesis or hemiplegia in tumors of the motor tract comes on slowly before the appearance of spasm.

Tumors of the postero-parietal region present some characteristic peculiarities. In several cases tumors were located in this region, and in several others the white matter of the parietal lobe was softened as the result of the obliteration of blood-vessels by the tumors. In general terms, we might say that hemianæsthesia, partial or complete, and impairment of sight and hearing on the side opposite to the lesions, seemed to be the most constant peculiarities.

Tumors and other lesions of the occipital lobes have in the last few years received extended attention, and, where possible, exact study, because of the opportunities which they furnish for corroborating the work of the experimental physiologists. It is unfortunate that the records of older cases do not furnish the exact detail which would render these tumors among the most important and interesting to be met with in the brain: some cases have, however, been observed with great care, and a few such are included in the table. To understand the special significance of the symptoms of such tumors, it will be well briefly to state some of the well-established facts about the function of the occipital cortex. The investigations of Gratiolet and Wernicke especially have proved that this surface of the brain is in direct connection with the fibres (1) which are continued upward from the posterior or sensory columns of the cord through the posterior portion of the internal capsule, and (2) with the expansion of the optic nerve, or the tract which passes, according to Wernicke, from the thalamus to the occipital lobe. There is but a partial decussation of the optic nerves at the chiasm, so that each half of the brain receives fibres from both eyes. This arrangement is best stated by Munk (quoted by Starr) as follows: “Each occipital lobe is in functional relation with both eyes in such a manner that corresponding halves of both retinal areas are projected upon the cortex of the lobe of the like-named side; e.g. destruction of the left lobe produces loss of function of the left halves of both retinæ.” This, of course, causes the right halves of both fields of vision to appear black. This condition is known as lateral homonymous hemianopsia, and was exhibited in several of the tabulated cases (Cases 40, 41, 42, and 43). It is probable that the dimness of the right eye recorded in Case 38 was really right lateral hemianopsia, as patients mistake this condition for blindness of that eye alone which is on the side upon which the visual fields are blank. It follows that this condition of the eyes will be caused by a destructive unilateral lesion at any point upon the optic tract behind the chiasm; and its exact nature and location are to be inferred from other corroborating symptoms. Among these corroborating symptoms, as will be inferred from the other functions of the occipital cortex, is especially to be considered partial hemiplegia and partial hemianæsthesia. This was observed in Cases 38, 40. These most characteristic localizing symptoms of occipital tumor have usually others, which, if not of such special importance, yet help to form a special complexus. Among these diffused headache is referred to by some writers as characteristic, but it seems to us that a localized headache, with pain on percussion over the affected region, is the only kind in this as in other regions which could have special diagnostic importance. Affections of hearing are recorded by some. It is not at all uncommon to have an incomplete hemiplegia and local paralysis. In Case 41 complete hemiplegia with facial paralysis is recorded. Local palsies, ocular and facial, are recorded in Cases 36, 37, 38, and 39. It is doubtless by transmitted pressure, or by extension of the tumor, or the softening caused by it, toward the motor fibres, that these more or less incomplete paralyses are caused. The general symptoms, such as vertigo, vomiting, and convulsions, are frequently present with tumors of the occipital lobes. We are at a loss to know upon what data of theory or experience Rosenthal bases his statement that psychic disorders are more common in occipital tumors than in those of the anterior and middle lobes, unless he refers simply to the hebetude and late coma which seem to come generally in these cases.