300 MANUAL OF EQUINE MEDICINE. 



excitement and frenzy. In some instances abnormal growths 

 in the brain are also injurious in virtue of their being part 

 of a general disease of the system, as, for example, in the 

 case of melanosis or other malignant growths. 



TREATMENT OF TUMOURS IN CONNECTION WITH 

 THE BRAIN AND ITS MENINGES. 



Drugs are of no avail in the treatment of these tumours, 

 but careful management of the work and dietetic arrange- 

 ments is in many instances attended with marked benefit. 



DISEASES DEPEN DING UPON ALTERATIONS 

 IN THE CEREBRAL CIRCULATION. 



MEGRIMS, OR CEREBRAL HYPERJEMIA. 



We have already alluded to ' megrims,' or cerebral con- 

 gestion, as being spoken of with other cerebral disturbances 

 of an organic or functional character, as ' staggers ' or 

 ' vertigo.' 



Definition. — By megrims we understand that form of 

 cerebral disturbance usually sudden in onset, of short 

 duration, liable to recurrence, and characterized by 

 excitement, perversion or im^Dairment of special sensation, 

 but also to some extent of common sensation and voluntary 

 motion (Robertson). 



This form of cerebral disturbance is liable to be confounded 

 with organic disease of the brain. 



Etiology. — Cerebral congestions may be mechanical (or 

 passive) or active. 



Passive congestion is generally due to interference with 

 the escape of the blood from the cranial vessels. 



Active congestion may be due to increased cardiac activity 

 or to disturbance of the vaso-motor influence, or may be 



