INFLAMMATION OF THE BRAIN ENCEPHALITIS. 257 



mg perceptible functional disturbances, and since encapsulated ab- 

 scesses frequently do not decidedly affect the circulation in the skull, 

 we may readily understand that we should occasionally find abscesses 

 of the brain on autopsy, which had not been suspected during life. 

 With this knowledge we may also understand those cases of cerebral 

 abscess which run their course without any symptoms except the inju- 

 rious influence they exercise on the general nutrition of the brain. It 

 s not at all rare for a patient to have dull headache, increasing 

 apathy, loss of thinking-power, even advancing to idiocy, a blunting 

 of the senses, increasing weakness, and uncertainty of movement- 

 symptoms which indicate the existence of severe brain-disease, it is 

 true, but which do not by any means justify a diagnosis of abscess of 

 the brain. Even the most experienced and accustomed observers 

 occasionally mistake abscesses of the brain. But these and similar 

 mistakes, which unfortunately are made public far less frequently 

 than brilliant diagnoses, can only seem strange to the ignorant, and 

 to those w T ho are not thoroughly acquainted with the physiology and 

 pathology of the brain, and with the diagnosis of brain-diseases. 



These latent cases of encephalitis are far less frequent than those 

 where the disease may be very strongly suspected or recognized with 

 certainty. If the abscess be located at a point where it destroys the 

 centres of special sense, or interrupts the conduction of the impulse of 

 the will to the motor nerves, or the impressions of special sense to the 

 organs, we have partial anaesthesia and partial paralysis, sometimes of 

 the cerebral nerves, again of the cerebro-spinal, at others of both. These 

 anaesthesias and paralyses riot unfrequently extend to both extremities 

 of one side of the body ; in other cases they are confined to the parts 

 supplied by certain cerebral or cerebro-spinal nerves, but in the latter 

 case also they are always on one side. Bilateral anaesthesias and paral- 

 yses only occur exceptionally, and in cases where the abscess is in the 

 middle portion of the brain, which is not double, or where different 

 abscesses are in the same parts of the brain on opposite sides. From 

 the occurrence of these symptoms we can only determine that there 

 is some local disease ; but we cannot decide on its nature, for they 

 occur in the most varied forms of local disease where nerve-filaments 

 and ganglion-cells are destroyed. To come to a conclusion on this 

 point, we must pay particular attention to the etiology, to the course 

 of the disease, and to those symptoms which show the effect of the 

 local disease on the rest of the brain. 



If we can make out that the symptoms of a local disease of the 

 brain have begun after an injury of the head, or if the patient has 

 caries of the petrous bone, the case is most probably one of ence- 

 phalitis. If, on the other hand, there has been no injury of the hoad f 



