330 ANATOMY OF THE CENTEAL NEETOUS SYSTEil. 



first those which are due to the effect of the tuinor upon the neighboring- 

 tissue; and, second, those which are due to general brain-pressure. We must 

 sharply differentiate these three groups: (1) local symptoms, (2) "neighbor- 

 hood-symptoms," and (3) general symptoms. Because of the narrowness 

 of the room beneath the tentorium cerebelli, the last two groups are often 

 especially emphasized. 



As symptoms induced through affection of the cerebellum itself — i.e., 

 local symptoms — we should enumerate the following: 1. The so-called cere- 

 iellar ataxia, which is almost without doubt a direct focal symptom of the 

 vermis only, and especially of its posterior half. A tumor could cause the 

 same symptoms if it be located in a hemisphere. It is possible for the 

 ataxia to be, in part, conditioned upon a weakness of the trunk-musculature. 

 2. Attacks of dizziness, — of real vertigo, — which are of especial importance 

 when appearing as an early symptom. 3. Possibly a kind of tremor which 

 is midway between ataxia and "intentional tremor," and a similar disturb- 

 ance of speech; these symptoms may, however, be simply due to the effect of 

 a tumor upon neighboring tissue ("neighborhood-symptoms"). The cere- 

 bellum does not appear to have direct relations to the motor functions in a 

 higher sense. Fvirther, its disease does not cause specific psychic disturb- 

 ances. 



In diseases of the cerebellum "neighborhood-symptoms"' occur espe- 

 cially through affection of the pons, the medulla, and the corpora quad- 

 rigemina. 



In the medulla oblongata and in the pons the extramedullary roots or 

 the medullary substance itself may be affected; later both are affected to- 

 gether. Especially important symptoms here are alternating hemiplegia and 

 possibly hemianesthesia, affecting the facialis and abducens on the side of 

 the tumor, the extremities on the opposite side, or disturbance of vision on 

 the side of the tumor. The extremities, however, may be affected i^pon the 

 side of the tumor or upon the opposite side, depending upon whether the 

 tumor exerts its influence above the decussation of the pyramid or below it. 

 The sudden death which is common in cerebellar diseases is probably a 

 "neighborhood-symptom" on the part of the medulla oblongata. The first 

 symptom manifested by the extramedullary nerves is frequently neuralgia 

 of the trigeminus. 



Neighborhood-symptoms on the part of the corpora quadrigemina are 

 bilateral ophthalmoplegias which affect mostly the outer branches of the 

 oculo-motorius and the trochlearis, leaving the internal recti and the abdu- 

 cens free. These symptoms are very common with cerebellar tumors. 



Prominent symptoms on the part of the cerebellar peduncles with 

 tumors of the cerebellum proper are rare; they are described above. 



The general symptoms are the same as those with other brain-tumors 



