240 DISEASES OF THE NERVOUS SYSTEM 



2. Inflammation of the soft Cerebral Membrane. Leptomeningitis. — 



The arachiiuicl is looseiu'd aiul dull. The subarachnoid chambers are filled 

 with more or less turbid fluid. The pia mater is hypersemic, loosened, 

 and covered by fibrinous exudation. The coverings of the brain are al- 

 most always infiltrated and detached from the pia mater with difficulty 

 and in some cases we find a serous or purulent fluid in the ventricles. In 

 a chronic case we find a circumscribed thickening of the cerebral mem- 

 branes and adhesions uniting the coverings with the brain, etc. 



3. Inflammation of the Brain Mass. Encephalitis. — This disease, as 

 a rule, involves single centres and causes a general irritation of the healthy 

 tissue without any distinctly marked limit. In the affected regions the 

 substance of the brain is swollen, hypenemic, and frequently filled with 

 small hemorrhagic centres. In the course of time, the inflamed cerebral 

 substance becomes softened and pulpy. This condition may be present 

 without any hemorrhage, but as a rule, the brain matter becomes red and 

 finally yellowish. This latter color is due to metamorphosis of the color- 

 ing substance of the blood or to fatty degeneration. These conditions are 

 divided into white, red, or yellow — softening of the brain. Finally cic- 

 atrices and cysts are formed, as in apojDlexy, or an abscess may be devel- 

 oped which is filled with thick yellow or greenish pus, which later becomes 

 encysted and sometimes solidified (calcareous). In some cases small en- 

 cephalitic centres may heal without leaving any trace. Occasionally we 

 see the development of a (non-inflammatory) softening of the brain with 

 thrombosis and embolus of the arteries; and, as a general rule, we find 

 symptoms which resemble apoplexy. 



Clinical Symptoms. — The symptoms of inflammation of the brain in 

 its early stages resemble those of hyperaemia. The animals are excited; 

 they run aimlessly from one side to the other, and are fretful and irritable. 

 They whine and howl constantly. The head is hot; the conjunctiva is 

 more or less reddened, the pupils are contracted, and reflex action is very 

 slight. The appetite is lost; constipation is generally present, with more 

 or less vomiting. The patient is indifferent to the impressions of external 

 objects, being sleepy and apathetic. Soon the disease changes in char- 

 acter. We see acute convulsions, especially those of the jaw, or eclamptic 

 convulsions. The animals cry and howl. At the same time the sphinc- 

 ters are relaxed, the animal apparently having no control of them. 

 Then there is an interval of quietness, in which the animal falls back into 

 a deep semicomatose contlition, and between these periods of quietness, 

 we very often see automatic movements, such as ([uivering or twitching of 

 one or two of the legs; also the corners of the mouth may be retracted. 

 Many cases either howl constantly, and at the same time seem to be semi- 

 comatose, or tliey may bark hoarsely (delirium). As a rule, the temper- 

 ature is a little above normal. Within a short time the aninuil becomes 



