Focal lesions of the pons are not so rare as to make the report of a single case of especial interest; and when of small size, up to a cherry-stone, it is not uncommon for them to be unattended with distinctive, if any, symptoms. This is particularly true of slowly growing tumors; but even large lesions may escape diagnosis if they give rise only to general symptoms, such as ordinary hemiplegia.
The most common morbid conditions in the region of the pons are hemorrhage, softening, abscess and tumor. When any of these is circumscribed, it may occasion localizing symptoms that are so distinctive as to render the diagnosis almost certain, but often the lesions extend to neighboring structures, and the symptoms are complex and varied.
On the dorsal aspect of the pons are situated the nuclei of origin of the trochlear, the trigeminus, the facial and the abducens, while near