vr] Clinical En'</cii<-c reyawliny Function 163 



Cases of Total Deafness. 



A perusal of the literature shows that instances of total deafness established on an 

 anatomical base, by a careful examination of the brain after death, are few and far between ; 

 in tin- works to which I have had access I cannot find more than five cases, and of these 

 the following is an abstracted account. 



In a well-known case reported by Friedlander and Wernicke, a gummatous lesion 

 destroyed the posterior part of the temporal lobe (including the first temporal gyrus) in 

 the left hemisphere, and a similar lesion in the right hemisphere invaded the most posterior 

 portion i >f the first temporal gyrus, the whole of the supramarginal and the adjacent part 

 of the angular gyrus. 



In a case recorded by Pick, the first temporal gyrus, along with the angular and 

 supramarginal gyri and the insula, on the left side, were obliterated ; and in the right 

 hemisphere, a destructive process extending from the insula further into the substance of 

 the brain, probably destroyed the auditory tract and so helped to make the deafness complete. 



Serieux and Mignot report a case in which the presence of hydatid cysts in both 

 temporal lobes gave rise to complete deafness. 



In a case of Anton's, bilateral patches of softening destroyed the first and second temporal 

 gyri, and from there extended in the direction of the occipital lobe and inferior parietal 

 lobule. 



Lastly, a carefully observed case has been put on record by Mills. In the left hemi- 

 sphere, the posterior two-thirds of the first temporal convolution were reduced to a thin 

 strip, and the posterior fourth of the second temporal gyrus partly destroyed by an old 

 embolic softening : in the right hemisphere, the first and second temporal gyri, the insula 

 and the lower end of the central gyri, along with the lenticular nucleus and external 

 capsule, had been wiped out by an old haemorrhagic process. 



Although on account of the extensiveness of the lesion, all of these cases were com- 

 plicated by other symptoms, such as paraphasia, paragraphia, word-blindness, paresis, etc., yet 

 the most prominent manifestation was the condition of absolute deafness and irresponsiveness 

 to sounds of any description ; again, although as guides to localisation they are necessarily 

 rough and inexact, it cannot be denied that they still further strengthen the evidence 

 gained from experiments on apes, to the effect that destruction of the superior temporal 

 gyri, and particularly of their hinder half, is adequate to the production of complete deafness; 

 and, lastly, although they do not tell us in so many words that the transverse gyri of 

 Heschl form a fundamental part of the auditory area, the fact that the lesions have always 

 been at the hinder end of the first temporal gyrus points in favour of this supposition. 



Cases of Deafness due to Unilateral Lesions, 



In face of the evidence given above we should naturally expect that destruction of 

 the superior temporal gyrus on one side would occasion either unilateral deafness, crossed 

 or on the same side, or bilateral deafness corresponding to hemianopia ; but it is a remark- 

 able thing that the information which we have on this point is of an extremely indefinite 

 and indeterminate character. True it is, that cases have been recorded in which bilateral 



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