222 DISEASES OF THE BRAIN. 



extended to the motor centres, has disappeared with the cicatrization 

 of the apoplectic clot. 



Hemiplegia occurs in some, but not in all, of the cases where the 

 effusion is into the cortical substance of the cerebrum ; these are gen- 

 erally accompanied by haemorrhage into the tissue of the pia mater. 

 The difference, doubtless, depends on how far the frequently-mentioned 

 results of the haemorrhage, compression of the capillaries, or collateral 

 oedema, extend inward ; whether they reach the corpus striatum and 

 thalamus or not. When the clot is in this position, general convulsions 

 are often observed, and in most cases there is severe disturbance of the 

 psychical functions. Since experience shows that persons with very 

 advanced and extensive degeneration or atrophy of the cortical sub- 

 stance (if it be only on one side) often have no psychical disturbance, 

 the frequent occurrence of the latter in apoplexy on one side is prob- 

 ably because haemorrhages readily affect the other hemisphere; and 

 particularly because this is likely to occur in the complicating inflam- 

 mation of the pia mater, which has a great tendency to spread. 



Haemorrhages in the pons, if of any considerable size, and in the 

 medulla oblongata, even if very slight, usually cause death. In small 

 effusions in the lateral portions of the pons, there are anaesthesia and 

 paralysis on the opposite side of the body ; in small extravasations in 

 the middle of the pons, there is paralysis of both sides. 



In haemorrhages of the cerebellum we often find paralysis of the 

 opposite side. But this cannot depend on the affection of the cerebel- 

 lum, for there is often no paralysis observed when this is extensively 

 destroyed. 



We must not think that, because haemorrhages are found at very 

 different parts of the brain, the different cases of paralysis dependent 

 on cerebral haemorrhages will differ widely from each other. On the 

 contrary, the large majority of cases show a great similarity, as they 

 induce the hemiplegia above described. It is, of course, of great prac- 

 tical importance to know this, which is simply explained by the fact 

 that, according to statistics, seven-eighths of all cerebral haemorrhages 

 are located in the cerebrum and particularly in the vicinity of the cor- 

 pus striatum and thalamus. There are some very wonderful excep- 

 tions to the one-sidedness of the paralysis and to its occurrence on the 

 opposite side, in haemorrhage of the cerebrum, which we are at present 

 unable to explain satisfactorily. However, we must add that, of late, 

 since all anomalies existing with the haemorrhage, particularly plugging 

 of the cerebral arteries, are more carefully attended to, and used in 

 explaining the symptoms, the number of such cases published has 

 greatly decreased. 



Another series of symptoms in cerebral haemorrhage, which is 



