186 DISEASES, OF THE BRAIN. 



occurring independently of mental influences, and convulsions affecting 

 the whole body, are the results of a morbid excitement of the cerebral 

 motor centres. It is very remarkable that general convulsions occur- 

 ring in cerebral hyperaemia and other affections of the brain, as well 

 as in epilepsy and eclampsia, are not accompanied by other symptoms 

 of cerebral irritation, but, on the contrary, are constantly combined 

 with symptoms of cerebral paralysis, especially with complete loss of 

 consciousness. By a series of valuable experiments, JZussmaul and 

 Tenner have shown that the same combination of general convulsions, 

 with loss of consciousness, may be induced by artificially obstructing 

 all the arteries supplying the brain with blood ; but it is entirely un- 

 explained, and it is enigmatical, how it happens that the same patho- 

 logical process induces a state of the greatest excitement in some parts 

 of the brain and paralysis in others. Until this contradiction is ex- 

 plained, the investigations as to whether the above symptoms depend 

 directly on the lack of oxygenated blood, or indirectly on changes oc- 

 curring in the blood, which remains unrenovated on account of the ob- 

 struction, are of little value. Since these attacks of convulsions are 

 constantly accompanied by symptoms of paralysis, and since we do not 

 believe that the latter can proceed from the pressure of the distended 

 vessels on the nerve-elements of the brain, and, lastly, since we may 

 artificially induce loss of consciousness and general convulsions by 

 preventing the flow of arterial blood to the brain, we consider the fol- 

 lowing decisions justifiable: The general convulsions and loss of 

 consciousness occurring during hyperaemia of the brain, which are usu- 

 ally termed epileptiform attacks, either occur because in passive hy- 

 peraemia the veins become so full that more arterial blood cannot en- 

 ter, or because the hyperaemia has induced a transudation of serum 

 into the perivascular spaces and interstitial tissue of the brain, with 

 consequent anaemia. Among the symptoms of psychical irritation, 

 there is first such a rapid change and loose connection between the 

 thoughts, that clear thinking is impossible. Along with this confusion 

 of ideas, the patient often has false notions about himself and the out- 

 side world, or delirium. 



Delirium is sometimes so real and intense that the patient cannot 

 distinguish it from true perceptions. This is the origin of hallucina- 

 tions and illusions. By the former we understand erroneous impres- 

 sions, which are considered as the product of direct perceptions, with- 

 out there being any actually existing external object corresponding to 

 the impression. The patients think they see animals and other ob- 

 jects which are not present, and that they hear voices when all is 

 quiet. By illusions, on the other hand, we understand the misappre- 

 hension or false interpretation of external objects which reallv exist. 



