What medical condition is characterized by episodes of severe pain in the back and legs?

The medical condition characterized by episodes of severe pain in the back and legs is sciatica, which occurs when the sciatic nerve is compressed or irritated. This nerve runs from the lower back through the hips and down each leg. Symptoms commonly associated with sciatica include intense pain, which may radiate along the path of the sciatic nerve, often causing discomfort in the lower back, buttocks, and legs. The pain can be sharp and severe, making it difficult for individuals to sit or stand comfortably.

In contrast, a herniated disk can also lead to back and leg pain, but it is a specific condition that may cause sciatica as a symptom rather than being identified as a standalone condition characterized by those symptoms. Epilepsy primarily presents with seizures and does not typically manifest as severe back and leg pain. Parkinson's disease is a neurodegenerative disorder that primarily affects movement and may involve muscle rigidity and tremors, but it does not specifically present with episodes of severe pain in the back and legs. Thus, sciatica is the most fitting diagnosis for the symptoms described.