Complex sentence: Neurosurgery, or the premeditated incision into the head for pain relief, has been around for thousands of years, but notable advancements in neurosurgery have only come within the last hundred years.
Split into simpler sentences: Neurosurgery, or the premeditated incision of ones head for pain relief, has been around for thousands of years. But, notable advancements in neurosurgery have only came within the last hundred years.