An infiltrating tumor at the base of the brain offers serious difficulties in diagnosis. This is particularly true in cases of tumor involving the mesencephalon, in which the few signs of an indeterminate nature make the establishment of a diagnosis practically impossible. Even with the aid of injections of air one often fails to differentiate a tumor of the mesencephalon from one of the cerebellum. For this reason it may be valuable to review the various syndromes associated with tumors of the mesencephalon in order, if possible, to establish some diagnostic criteria of value.
REPORT OF CASES
The first feature which strikes one on reviewing the syndromes associated with tumors of the mesencephalon is the fact that there is no constellation of signs and symptoms which can be said to be present in all cases of tumor in this region. This is not surprising in view of the many structures