626 Injuries and Concussion of the Brain. 



animals resulting from Iji'uising" of the peduncle of the cere- 

 bellum or the posterior portion of the optic thalamus is "waltz- 

 ing" or rolling or falling over on one side. These movements 

 are also seen in cases of paralysis of some of the cranial 

 nerves, or in cases of obliquity of vision (see page 593). Lat- 

 eral displacement of the head and neck are seen after injuries 

 involving one hemisphere, the peduncle of the cerebellum, or 

 neighboring tissues. When the head is turned to one side, the 

 animal moves in circles, if movement be possible at all. Many 

 injuries of the hemispheres are followed by epilepsy of the 

 Jacksonian type (see epilepsy). 



Hemianesthesia frequently follows concussion of the brain 

 and it is sometimes very difficult to discover even after the 

 disappearance of the coma. Paralysis of the sensory nerves 

 is easily recognized (trigeminus, glosso-pharyngeal, vagus). 

 Concussion is often followed by uni- or l)ilateral blindness, the 

 exact nature of which has not been ascertained. 



After the lapse of a certain length of time, local symptoms 

 may disappear either partially or completely if the affected 

 portion of the brain be subjected only to pressure of extrava- 

 sated blood in the neighboring tissue, or if it is not completely 

 destroyed. 



In many cases, in addition to the nervous symptoms, evi- 

 dence can be found of the effects of the blow such as wounds, 

 changes in the form of the cranium, increased sensitiveness, 

 etc. When the base of the cranium is fractured there is very 

 often injury to the vessels of the pharynx or ear, and there 

 may be hemorrhage from both nostrils or the ears immediate- 

 ly or soon after the injury is inflicted. 



The following are the symptoms of cerebral hemorrhage in birds: 

 The head and neck are twisted on the long axis in such a way that 

 the parietal region is directed to one side or even downwards, thus mak- 

 ing it difficult or impossible for the bird to take food or water. While 

 walking, they fall down on the slightest provocation, and are seized 

 with convulsions. In many cases, they appear giddy, and stumble, or 

 move in circles, move backwards or suffer severe disturbances of con- 

 sciousness, and have epileptiform seizures. 



Diagnosis. Diagnosis is rarely difficult. Difficulty arises 

 in cases in which no injury can be discovered. In such cases, 

 cerebral hemorrhage, embolism of vessels of brain, and enceph- 

 alitis nmst be taken into consideration. In the absence of 

 causal factors that are likely to be followed by encephalitis, 

 the sudden appearance of disease unaccompanied by fever in- 

 dicates an injury. In birds, contagious diseases, such as fowl 

 cholera and chicken pest, must be borne in mind and also the 

 fact that disease of the inner ear in chicken pest, diphtheria, 

 chicken pox and suppurative inflammation of the ear may 

 cause the head to be rotated on its long axis or turned to the 

 side. 



