Ictal: Related to a seizure (as in, the ictal focus is the location where a seizure originates). Find out more about Epilepsy Surgery.
Instrumentation: Metal supports sometimes used in spinal fusions to help steady the spine while it fuses. Common types of support include plates, rods, or screws.
Internal fixation: The insertion of metal rods, wires, pins, screws, or plates (or a combination of these) into bone fragments.
Intra-arterial: Delivered into an artery (as opposed to intravenous, which is delivered into a vein).
Intra-arterial catheterization angiography: An invasive study in which a catheter (a small tube) is placed in an artery (usually the femoral artery) and guided into the arteries in the neck and head. Contrast material is injected, which makes the blood vessels visible on an x-ray image.
Intracerebral hematoma: A blood clot within the brain.
Intracranial pressure (ICP): The overall pressure inside the skull.
Intrathecal: Within a theca or the dura mater membrane that surrounds the spinal canal.
Intravenous: Delivered into a vein.
Ischemia: Inadequate circulation of blood, generally due to a blockage of an artery. More about ischemic stroke.