Diseases of the Nervous System 



Section I. 



DISEASES OF THE BRAIN. 



General Symptomatology of Diseases of the Brain. 



Organic diseases of the brain and its membranes are char- 

 acterized partly by s>anptoms of a general nature and partly 

 by focal symptoms. The general symptoms are caused either 

 directly by diffuse disease of the cortex of the brain associated 

 with an increase of intracranial pressure, or b}'- an increase of 

 pressure alone. On the other hand localized symptoms are, as 

 a rule, associated with disease of definite portions of the brain 

 connected with certain functions. These two groups of symp- 

 toms may be present simultaneously, or either may be present 

 separately. 



(a) General Cerebral Symptoms. 



The most constant sjTiiptoms of disease of the brain are 

 various forms of disturbance of consciousness. There may be 

 numbness, dulness, stupor to varying degrees, or complete 

 coma, and they are generally associated with lessened sensibility. 

 The symptoms may set in suddenly as in cases due to hemor- 

 rhage, concussion or embolism. In other cases the onset is 

 slower as in acute encephalitis and meningitis, hyperemia and 

 anemia of the brain. Finally the symptoms may take weeks, 

 months or even years to develop as in chronic hydrocephalus, 

 tumors, parasites, encephalitis due to distemper in dogs. Not 

 rarely during the course of diseases of the brain there are re- 

 missions of the symptoms. In cases where the disease is less 

 extensive or is localized in the neighborhood of the medulla ob- 

 longata there may be a complete absence of them, and cases 

 have been observed in which in spite of a considerable but slowly 

 progressive reduction in the size of the cranial cavity the ani- 

 mals have shown no symptoms whatever. 



In acute diseases of the brain, excitement is generally ob- 

 served, a condition of disturbed perception with simultaneous 

 acceleration of the motor reaction, which, as a rule, is of short 



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