HYPEREMIA OF THE BRAIN 235 



eyelids on touching the conjunctival ]nill)i or the cornea and the puj^il 

 with 'its contraction or dilatation on the impression of light. 



DISEASES OF THE BRAIN AND ITS COVERINGS. 

 Hyperaemia of the Brain. 



Etiology. — There is an active and passive hyperaemia. Active hy- 

 pera?niia of the brain is caused by an increase of the circulation as the 

 result of increased heart-action. This occurs in hypertrophy of the left 

 ventricle, from excitement, in young animals, from heat (sunstroke), in 

 great bodily exertion, in teething, high temperture; blows, nervous tem- 

 perament, from overeating, the effects of certain narcotics, and as a 

 secbndary symptom of certain diseases. 



Passive hyperaemia (stagnation) occurs in compression of the jugular 

 veins by tumors, such as large goitres, by obstructed respiration, from 

 tight collars, in acute bronchitis, and in compressed conditions of the lung 

 due to hydrothorax, extended indurations of the lungs, defects in the ve- 

 nous openings of the heart. Hypersemia of the brain accompanies various 

 acute internal diseases, and as a secondary symptom of a large number of 

 disorders; it is also seen as a result of various poisons, such as alcohol, 

 certain narcotics, etc. 



Pathological Anatomy. — As a rule, hyperemia of the brain occurs in 

 connection with congestion of the coverings of the brain, especially the 

 pia mater. When hyperaemia is very intense, or where it has existed 

 for a long time, we cannot definitely separate the conditions. We find 

 the dura mater distended, but very little changed. The vessels of the pia 

 mater are much injected, the torsions of the vessels are flattened, and the 

 sulci are perfectly flat as if pressed out of shape. We find the gray matter is 

 darker than usual, while the white brain substance is dull gray or yellow- 

 ish red, and presents numerous bloody spots which may be easily removed. 

 In chronic conditions of this disease, we find venous hyperaemia. The 

 brain appears in such cases pale and anaemic, very moist and soft, and on 

 section has a brilliant, mirror-like lustre. It is lessened in size and doughy 

 in consistence and the subarachnoidal fluid is increased. 



Clinical Symptoms. — The symptoms of active hyperaemia of the 

 brain are characterized by a sudden development of excitable symptoms. 

 These consist in great restlessness, running around, making frequent 

 changes of position, irritability, a tendency to biting and attacks of de- 

 lirium, partial or general convulsions, and an increased activity of the act- 

 ion of the heart. The pulse is quick and irregular; the respirations are 

 short. There is congestion of the mucous membranes of the head, and the 

 upper portion of the head is warm to the touch. There is contraction of 



