102 LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



The thalami are everywhere in such close juxtaposition to the internal 

 capsule that we very seldom see cases of disease which involve them alone. 

 Even in these cases it is doubtful to what extent the symptoms present depend 

 upon involvement of the neighboring fibres of the internal capsule. It is, there- 

 fore, impossible to determine the symptom-complex presented by disease of the 

 thalami. According to Meynert the sensations of innervation of the upper ex- 

 tremities are injured. As a result we would have delusjons as to the position of 

 the limb, and, in consequence of these delusions, forced attitudes would be 

 assumed. Neither motor nor sensory paralyses seem to be caused by injuries to 

 the thalami. Injuries to sight in the form of homonymous, lateral hemianopia, 

 and, perhaps, also of crossed aniblyopia, have been repeatedly observed. In 

 disease of the thalamus there have often been observed symptoms of hemichorea, 

 athetosis, and tremor of one side of the body. These last symptoms, however, 

 have also been observed in disease of other parts of the brain. 



The same obstacles present themselves in attempting to 

 define the symptoms of disease in the corpus striatum. Those 

 symptoms, which were formerly considered as indicating disease 

 at this point (hemiplegia, for example), may equally well be 

 caused by disease of the neighboring internal capsule. One 

 case of disease of the putamen is known to have run its course 

 without giving rise to symptoms which pointed to trouble in 

 that locality. 



If an affection of the base of the brain only involves that 

 part which lies in front of the pons, the symptoms caused by 

 the irritation or paralysis of the nerves in that region are far 

 more important, for diagnostic purposes, than anything else. 

 If the pedunculi are also involved there may be associated with 

 these symptoms motor and sensory disturbances of the ex- 

 tremities. A careful analysis of the symptoms, in connection 

 with an accurate knowledge of the anatomy of the base of the 

 brain, often leads to very clear and exact diagnosis as to the 

 locality affected. 



