Which condition is characterized by a sudden reduction in blood flow to the brain?

The condition characterized by a sudden reduction in blood flow to the brain is a transient ischemic attack (TIA). A TIA occurs when there is a temporary decrease in blood supply to a part of the brain, typically lasting only a few minutes, and usually resolves without permanent damage. This interruption in blood flow can lead to symptoms that mimic a stroke, such as weakness, numbness, or speech difficulties, but the key difference is that TIAs do not cause lasting effects.

While hemorrhagic stroke, cerebral embolism, and seizure disorder involve serious neurological events, they do not specifically denote a transient reduction in blood flow in the same manner as a TIA. Hemorrhagic stroke involves bleeding in or around the brain, cerebral embolism refers to a blockage caused by an embolus traveling to the brain, and a seizure disorder is related to abnormal electrical activity in the brain but does not inherently relate to blood flow dynamics. In summary, a transient ischemic attack is explicitly defined by its temporary nature and its direct connection to reduced cerebral blood flow, making it the correct response to the question.