There are few experiences more humiliating than to overlook a subdural clot when operating for intracranial hemorrhage in traumatic cases. To be sure, in the majority of instances the surgeon has sufficient signs and symptoms on which he can rely to make a correct localizing diagnosis; but occasionally cases present themselves which are baffling from the standpoint of localization. It has usually been my experience to find a hemorrhage on the side of the dilated pupil regardless of other neurologic aspects, and it is my purpose to report the following cases to emphasize the importance of "following the pupil."
It has been taught that the pupils go through two reactive phases in cases of damage to the brain or hemorrhage. The first or irritative phase is said to cause constriction of the pupil which later may change to dilatation if the cortical pressure becomes high enough on the side in