CEREBRAL SURGERY WITHOUT ANESTHETICS 565 



And, first, it would seem that the cerebral hemispheres, including 

 their integuments, are largely or completely devoid of the capacity of 

 self-feeling. It has been known for some time that the substance of 

 the brain is insensitive to pain; but it has hitherto been held that the 

 dura is a highly sensitive tissue. This belief was strengthened by the 

 knowledge that this membrane receives its innervation from the tri- 

 geminal nerve, and by the experience that in trephining the lower 

 animals, when the dura is reached, struggling, and rise in blood-pres- 

 sure are common. But here was a fully conscious subject, able 

 intelligently to describe his sensations, who felt no pain while the 

 membranes over that part of the brain which is allotted to sensory im- 

 pressions were incised and manipulated. This experience, therefore, 

 throws back upon us the problem: What is it that causes intra- 

 cranial pain, especially in the form of those intense headaches which 

 follow upon disturbances of the cerebral blood-supply, or in cases of 

 cerebral lesion like that now under discussion? May we not find that 

 the causes of the pains which we locate in the cerebral hemispheres 

 invariably lie outside of those hemispheres? Certainly, it is not 

 strange that the localization in such cases should be even more in- 

 definite than in the case of an aching tooth or some form of abdomi- 

 nal distress. Indeed, cerebral pains and other forms of discomfort, 

 with their accompanying mental disturbances, may be so severe as to 

 result in insanity, and yet the location of the irritating causes, 

 whether nearby or remote from the brain, remain undiscovered. 



Second, there is both additional light and increased confusion con- 

 tributed by these cases of cerebral surgery without anesthetics to the 

 problem of the functions of the post-central and so-called sensory 

 convolutions. In both these cases stimulation of the motor strip 

 called out motor responses; stimulation of the post-central area failed 

 to call out motor responses. More important still by far is the fact 

 that, in the second case, stimulation of the post-central convolutions 

 was followed by distinct sensory impressions — not mere signs of such 

 impressions, but conscious sensations, testified to in language by their 

 subject; and these sensory impressions were located in the extremities 

 and not at all in the cortex itself. This is definite and fairly con- 

 clusive evidence to the functional value of the post-central convolu- 

 tions. But now, on the other hand, we have the fact that, although 

 the incision was made in the middle of the field supposed to be es- 

 pecially if not exclusively sensory, no subjective sensations whatever 

 were called forth in this way ; and the yet more startling fact — T quote 

 the words of Dr. H. M. Thomas, clinical professor of neurology in 

 Johns Hopkins University — that. 



With a tumor situated in large part in the post-central convolutions and 

 involving a considerable portion of its superior part, there was practically no 

 objective sensory loss. I think it may fairly be said that before the first 



