634 Purulout Encephalitis. 



the nerve cells, general symptoms make their appearance, and 

 where certain parts of the brain nndergo degeneration there 

 may also be symptoms of a local nature. On the other hand, if 

 the process of abscess-formation is slow, the general symptoms 

 may be quite insignificant or even absent. 



Anatomical Changes. In cases in which the disease has 

 ])een in existence for some time the inner surface of the abscess 

 appears to be covered with a finely granular membrane some 

 millimeters in thickness, the socalled "pyogenic membrane." 

 The pus is white or reddish in color and sometimes has an offen- 

 sive odor. In very exceptional cases the pus appears to be 

 mixed with blood, owing to the rupture of a vessel on the inner 

 surface of the abscess cavity. In the majority of cases the ab- 

 scesses occur in one of the hemispheres and more rarely in the 

 cerebellum. If they are superficially placed the disease may 

 extend to the membranes and set up suppurative processes 

 there. In deep-seated abscesses rupture may occur in the ven- 

 tricles. When the lesions are due to metastasis the abscesses 

 are usually more numerous. Joline found ten and Delamotte 

 and Brocherion fourteen abscesses in the brain. Abscesses 

 caused in other ways are usually solitary and vary in size. In 

 a case recorded by Priimer the cerebellum was converted into 

 a cavity full of pus. Frohner records a case in which pus col- 

 lected in the lateral ventricles as a result of fracture of the 

 frontal bone (pyocephalus). 



Symptoms. The rapid development of one or more ab- 

 scesses causes a rise of temperature, provided there is not fever 

 already, owing to some primary disease, and the temperature 

 is subsequently maintained with pronounced variations. As 

 in the case of meningitis there is a rapidly progressive dullness, 

 which at intervals may give place to symptoms of excitement 

 which may amount to mania. In other cases there is great 

 uneasiness from the outset, but exceptionally there may be no 

 evidence of excitement even up to the time of death. Although 

 both the dullness and the excitement tend to be very marked, 

 these cannot be taken as characteristic of suppurative encepha- 

 litis. In many cases there are fibrillar contractions and clonic 

 spasms in various parts of the body, and there may be forced 

 movements. Paralysis of various cranial nerves has been ob- 

 served. Death may take place within a few days or a week or 

 two, the symptoms and especially those of excitement having 

 gradually become more severe. 



Witii the foregoing must be included cases in which the 

 cerebral abscess remains latent for a time and then causes death 

 in one or two days, the animal showing the symptoms al- 

 ready descril)ed (Bouchet, Eoder, Johne). Such a course of 

 events is likely to happen in cases in which the process of ab- 

 scess-formation has proceeded slowly up to a point and then 



