HYPEILEMIA OF THE BRAIN AND ITS MEMBRANES. 183 



indicate that the disorder has a definite material basis, which in bad 

 cases is not always repaired.] 



Lastly, the symptoms of acute alcoholic poisoning, as well as that 

 from opium and other narcotics, do not depend at all, or at any rate 

 depend to a very small extent, on over-fulness of the cerebral vessels, 

 although in them the brain is hyperaemic. The case appears to be 

 different in the symptoms induced by the immoderate use of liquor 

 for a length of time, or the continuous misuse of narcotics, a practice 

 which has greatly increased since the introduction of subcutaneous 

 injections of morphine. In such cases cerebral hyperaemia plays a 

 more important part, at least, than it does in the symptoms of intoxi- 

 cation and of acute opium-poisoning. 



[Abnormal fulness of the brain and its membranes is a common 

 enough affection. Its symptoms may vary greatly. Not unfre- 

 quently they are so insignificant as to attract little or no attention ; 

 so that many persons with habitual plethora about the head are fa- 

 miliar with the sensation which it causes, and do not consult a phy- 

 sician. But there are other cases in which hyperaemia causes symp- 

 toms of the utmost gravity ; and between the mere sense of giddi- 

 ness after stooping which one man may feel, and the formidable 

 nay, fatal apoplectiform seizure which may befall another, there is 

 a long series of interchanging types, whose differences, however, by 

 no means always correspond to differences in grade of the hyperae- 

 mia. Most of the symptoms bear the character of a morbid nervous 

 excitement with exaltation, although others take on the form of 

 depression and paresis. The psychical, the sensory, or the motor 

 functions may be especially disturbed, according to the seat of the 

 hyperaemia and to the receptivity of the individual. One might at 

 first suppose that the symptoms of an active hyperaemia of the brain 

 should be widely different from those of a passive congestion ; since 

 in the first there is an increased afilux to the brain of arterial blood, 

 the constant supply of which is so essential to the continuance of 

 the brain-function, whereas in the latter this arterial supply must be 

 more or less diminished, and the symptoms of carbonic-acid poison- 

 ing should also be present. But in reality the two forms of hyperse- 

 mia bear a close resemblance ; and this is due to the fact that a lack 

 of blood in the brain is capable of causing like symptoms with those 

 from overloading of the brain with arterial blood ; and it is well 

 known to the practitioner that the distinction between cerebral hy- 

 peraemia and cerebral anaemia may present obstacles at the bedside 

 only to be surmounted by prolonged observation of the patient. 



The symptoms of the mildest grade of hyperaemia of the brain 

 consist in a feeling of pressure and weight in the head, or of an 

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