The field defects produced by temporal lobe lesions / by Harvey Cushing.
- Cushing, Harvey, 1869-1939.
- Date:
- 1921
Licence: In copyright
Credit: The field defects produced by temporal lobe lesions / by Harvey Cushing. Source: Wellcome Collection.
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![Three years before, in a paper which has received an undeserved lack of attention, Meyer [5] had described “ the peculiar detour of the ventral portion of the geniculo-calcarine path which simulates the existence of an inferior longitudinal fasciculus.” By the study of secondary degenerations following old vascular or traumatic lesions which had shown a fortunate limitation, either by exclusion or inclusion, to the visual pathway, he had observed that a portion of the optic radiation, on leaving the geniculate body, plunges far forward into the temporal lobe to sweep around the horn of the ventricle before it turns backward to end in the calcarine cortex. Though Meyer’s findings were merely corroborative, in large part, of those by his predecessors—Flechsig, Henschen, Archambault [1], and others—he was able to demonstrate the course of isolated paths which show not only that the dorso-lateral and ventral bundles remain the same size throughout, but that they maintain in their course a definite position in relation to other bundles. Thus, the dorso-lateral bundle not only remains the most dorsal, but the most direct, all the way from the geniculate body to its end stations. The most ventral bundles, on the other hand, are the ones which make the longest detour around the temporal horn to end in the anterior part of the calcarine cortex. A glass-model reconstruction of these fibres was made by Dr. Meyer, and it is from this that, at my request, he has permitted Max Brodel to make the superb diagrams (figs. 3, 4, and 5), which accompany this paper. They render superfluous any further written description. Meyer’s own observations were not supported or confirmed by perimetric tests, which were difficult or impossible in the clinical material of the type he had at his command. Nevertheless, he shrewdly surmised in connection with the few reported cases of quad¬ rant hemianopsia in which small defects had been found post mortem that the dorsal bundles have an upper retinal distribution and hence correspond with field defects in the lower quadrants, whereas per contra involvement of the ventral bundles is responsible for defects of the upper field quadrants such as was shown in fig. 2. In other words, the disposition of the fibres in the geniculo-calcarine radiation is practically the same as that in the optic nerve itself. Whether or not this means, as I believe it does, separate representation on the cortex for different areas of the retina, need not now detain us, for our present concern lies with the course of the fibres through the temporal lobe and not with their calcarine end-stations. From the series of cases to be reported, we shall see that tumours](https://iiif.wellcomecollection.org/image/b29813281_0006.jp2/full/800%2C/0/default.jpg)
