Subspecialization of physicians and regional centers concentrate the volume of certain rare cases into fewer hospitals. Consequently, the primary institution of a Neurosurgical Resident Training Program may not have sufficient case volume to meet the current Residency Review Committee case minimum requirements in some areas. To ensure the competency of graduating residents through comprehensive neurosurgical education, programs may need residents to travel to outside institutions for exposure to cases that are either less common or more regionally focused.