HYPERAEMIA OF THE BRAIN AND ITS MEMBRANES. 1Q5 



exactly identical with those of cerebral anaemia ; this is true in regard 

 to congestive hyperaemia and anaemia, and the explanation of the cor 

 respondence is easy. In both cases the brain lacks its new supply of 

 arterial blood. To explain the symptoms of paralysis occurring in 

 fluxionary hyperaemia also, we must take the hypothesis that, during 

 its course, there is a secondary oedema of the brain, as a result of 

 which we have capillary anaemia, a condition directly opposite to the 

 original hyperaemia. The symptoms of cerebral hyperaemia are ren- 

 dered more varied by the fact that, in different cases, the irritation or 

 paralysis is more prominent at one time in the sensory, at another in 

 the motory, and again in psychical functions. We cannot give any 

 satisfactory explanation of this difference. 



Among the symptoms of irritation in the sensory functions are 

 headache, great sensitiveness to external impressions, and simple sub- 

 jective impressions from the nerves of special sense. The headache, 

 a very frequent symptom 1 in #11 cerebral diseases, is very difficult to 

 explain ; we do not even know if it is of central origin (that is, if it 

 originates in the parts of the brain where irritation causes symptoms 

 of pain after the insensible greater hemispheres have been removed), 

 or whether, as I think is more probable, it depends on irritation of the 

 filaments of the trigeminus going to the dura mater. The great sen- 

 sitiveness to impressions on the senses depends on the increase of ex- 

 citability caused by the cerebral hyperaemia on the hyperaesthesia of 

 those portions of the brain through which peripheral irritations are 

 perceived. The patients do not exactly feel, see, and hear more sharply 

 than ordinarily, but they are annoyed by irritations far weaker than 

 such as usually annoy them. Light troubles them ; a slight sound, or 

 an insignificant irritation of the nerves of touch, excites disagreeable 

 feelings. Morbid excitation (which must not be identified with in- 

 creased excitability) of the same central parts causes the dazzling be- 

 fore the eyes, seeing sparks, roaring and buzzing in the ears, the sen- 

 sation of formication, or of undefined pain, which are not induced by 

 peripheral irritation. Among the motory symptoms of irritation we 

 have restlessness, sudden starting, gnashing the teeth, crying out, 

 without the expression of pain, the automatic movement of the ex- 

 tremities, twitching of single muscles, and lastly the general convul- 

 sions which are observed in the course of cerebral hypersemia. In re- 

 gard to the first of these symptoms, particularly the restlessness, the 

 constant tossing around in bed, we may often be doubtful whether it 

 depends on increased excitability of those portions of the brain through 

 which the motor nerves and muscles are excited and motions induced, 

 or on morbid states of excitement in the organs affected. On the 

 other hand, there is no doubt that the twitching of individual muscles, 



