What is Todd's paralysis characterized by?

Todd's paralysis is characterized by a temporary period of paralysis or weakness that occurs after a seizure. This phenomenon typically follows focal seizures, where the paralysis can affect a specific part of the body that corresponds to the area of the brain involved in the seizure activity. While the paralysis may last from minutes to a few hours, it is usually self-limiting and resolves completely over time.

The other options describe conditions that do not pertain to Todd's paralysis. A chronic autoimmune disease affecting both brain hemispheres would suggest a condition like multiple sclerosis, which is unrelated to seizure activity. The description of a neurological disorder indicated by a large birthmark might refer to Sturge-Weber syndrome, which is also not directly associated with Todd's paralysis. Finally, progressive loss of motor function over time is a feature associated with neurodegenerative diseases rather than the transient effects seen in Todd's paralysis.