482 



Mr. L. Hill. On Cerebral Anmnia and the 



4. The Late Effects which follow Ligation of the Four Cerebral Arteries. 



These vary in different animals. Almost all rabbits die from failure 

 of respiration within three minutes, after convulsions of an asphyxial 

 type. There occur vagal inhibition of the heart, general vaso-constric- 

 tion, and a high arterial pressure, prior to the failure of the circulatory 

 system. The symptoms are in every way similar to those produced by 

 clamping the trachea. 



Cats become comatose and die within a few hours from respiratory 

 paralysis, which is gradual in onset. Cheyne Stokes respiration some- 

 times results, and at a later stage long-drawn spasmodic gasps of the 

 diaphragm occur at rare intervals. Extensor rigidity often occurs 

 before death. Cats may survive the ligation of the two carotids and 

 one vertebral artery. 



Dogs recover from ligation of the four cerebral arteries, some after 

 scarcely any symptoms, others after passing through a stage of 

 dementia, accompanied by paralysis and anaesthesia, which lasts three 

 or four days. The dogs during this period of dementia behave exactly 

 like the dogs in which Goltz produced extensive destruction of the 

 cerebrum. The spatial sensations depending on the nerves of skin, 

 joints, and muscles are no longer brought into association with the 

 sensations which are derived from the higher senses. Eeflex defence 

 and locomotor movements alone persist. Monkeys almost all die 

 within twenty-four hours after ligation of the two carotids and one 

 vertebral artery. The animals become soporose and then comatose. 

 Extensor spasms, extensor rigidity, and failure of respiration follow. 

 Monkeys recover without symptoms after ligation of both carotids. 



In one monkey, after the two carotids and one vertebral artery had 

 been tied, there ensued extensor rigidity and profound paralysis and 

 dementia. This animal was kept alive by spoon feeding and continued 

 in the same state. It was killed on the fifth day. The stage of sopor 

 and coma or dementia may not appear in dogs or monkeys for an 

 hour or so after the ligation of the arteries has been effected. On 

 recovering from the anaesthetic the animals may at first appear lively 

 and intelligent. 



In man the ligation of one carotid artery is not free from risk, while 

 the ligation of both carotids is recognised as a most dangerous opera- 

 tion. The two arteries can be tied successfully at intervals of time. 



Attention is more particularly drawn to the following conclusions 

 deduced from this research : — 



1. The cerebral circulation of man, in the erect posture, depends on 

 the tone and activity of the skeletal and respiratory muscles. The 

 blood and lymph are returned from the lower parts to the heart by 

 the expressive action of the muscles and constant change of posture. 



2. The functions of the brain may continue after a great diminution 



