ANAEMIA OF THE BRAIN AND ITS MEMBRANES. 199 



tension, by too great or too slight a fulness of the vessels, modifies 

 the excitability of the brain in the same way. I have already said 

 that this, is a hypothesis, and, I may add, that it is difficult for me to 

 believe that, in anaemia of the brain, the symptoms of irritation depend 

 on an inconsiderable, and those of paralysis on a decided, diminution 

 of the normal pressure of the blood-vessels on the brain. On the other 

 hand, it is a physiological fact that the excitability of a nerve is in- 

 creased a short time before it is entirely lost, and that the greatly- 

 increased excitability of a nerve is not a sign of increased normal nu- 

 trition, but, on the contrary, of its diminution. It is true we do not 

 know why this is, but the knowledge that it is so renders it less 

 strange thac, in gradually-developing anaemia of the brain, symptoms 

 of irritation should, as a rule, precede those of paralysis, and that, 

 where the anaemia does not attain a high grade, only the symptoms of 

 irritation should be seen. 



Occasionally the symptoms of anaemia consist chiefly or exclusively 

 of disturbances of sensibility. The patients complain of severe head- 

 ache, either in the forehead or occiput ; they are sensitive to light and 

 sound, have flashes before the eyes, noises in the ears, dizziness, etc. 

 These symptoms occur most typically after severe metrorrhagia and 

 other extensive losses of blood, and frequently only the consideration 

 of the cause, the pulse, color of the skin and lips, and the symptoms of 

 want of blood in other organs, enable us to decide that there is anae- 

 mia, and not hyperaemia, of the brain. 



In other cases of anaemia of the brain, particularly in children, the 

 motor disturbances are more prominent. The symptoms of anaemia 

 of the brain in children from exhausting diarrhoea and other debilitat- 

 ing causes, so-called hydrocephaloid, often so closely resemble those 

 of acute hydrocephalus, that the distinction of the two states may be 

 very difficult. Marshall Hall divides hydrocephaloid into two stages, 

 one of irritation, one of torpor. In the first stage the children are very 

 restless and capricious, constantly toss about in bed ; readily fright- 

 ened, they cry out in their sleep, gnash their teeth ; the face is usually 

 flushed, the pulse frequent, and temperature elevated. There is al 

 most always slight twitching of some limbs, frequently also there are 

 general convulsions. In the second stage the children collapse, be- 

 come entirely apathetic, no longer attend to objects held before them ; 

 the eyelids are half closed, the pupils insensible to light ; respiration 

 becomes irregular and rattling ; finally death occurs with symptoms of 

 coma. Since we regard the so-called symptoms of pressure in diseases 

 of the brain and its membranes (among which are effusions into the 

 ventricles), which encroach on the cranial cavity, as due to compres- 

 sion of the capillaries and obstruction of the supply of arterial blood 

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