424 Xei'Z'oits Distitrbaiices. 



oblongata, in which the circulatory and respiratory regulative 

 apparatus are located, must necessarily inhibit or depress these 

 most vitally important functions and thus threaten life. Lesions 

 of the cerebral cortex bring about varying grades of disturbance 

 of consciousness, which, including all phases of mentality, may be 

 collectivel}' spoken of as psychical disturbances. 



The most severe of the ps}-chic paralyses is cerebrospinal 

 cuiicnssioii {commotio cerebri et meduUcc). After more or less 

 severe concussion of the head or the whole body by a fall, blow 

 ()r kick, the functions of the brain and cord cease. Anatomically 

 there is often nothing to be found in such a case, beyond slight 

 luemorrhagic effusions upon the membranes and the skull, and 

 gross lesions of the nervous structures are absent. The severe 

 symptom complex can only be explained by supposing that 

 through the influence of the concussion waves upon the exceed- 

 ingl\- complicated mechanism of the nervous system (compres- 

 sion alternating with stretching force) minute structural changes 

 nuist be induced, as destruction of the delicate dendrites of the 

 nerve cells (Krehl). 



Cessation of the cerebral function is manifested by complete 

 loss of consciousness, loss of all voluntary muscular motility, 

 loss of pupillary reactions, weak pulse and coolness of the exter- 

 nal surface ; and tends usually, in a few minutes, hours or days 

 to death. In other and milder instances only a transient loss of 

 sensibility occurs. When the cord is the main part involved by the 

 concussion there are met paralysis of the extremities, loss of sensa- 

 tion in the latter and in the trunk, and disturbances of respiration, 

 as the principal symptoms. Sudden and usually brief disturb- 

 ance of equilibrium and inability to maintain an upright posture 

 (dizziness, I'erti'i^o), associated with loss of consciousness (faint, 

 syncope), occur from disturbance of the blood circulation in the 

 cerebral cortex and in the cerebellum ; they niay result too from 

 trivial grades of general anjemia of the brain, as a decrease in 

 the arterial supply, and also occur in passive congestion (cardiac 

 disease, compression of jugular veins) or from anatomical 

 changes of the cerebellum, aural disease and toxic influences. 

 In uncomplicated loss of consciousness the cerebral cortex is 

 alone the seat of involvement ; the animal suddenly begins to go 

 slowly, stops for a moment, staggefs, leans against the shafts 

 or other support, turns around in a circle and falls ; then, after 

 remaining motionless for a few minutes, attempts with labored 

 movements of the limbs to get up. and is gradually able to rise and 



