A myoclonic seizure is a single or series of jerks (brief muscle contractions). Each jerk is typically milliseconds in duration. Myoclonic status epilepticus is characterized by ongoing (> 30 minutes) irregular jerking, often with partially retained awareness. These two features distinguish a myoclonic status epilepticus from a generalized clonic seizure, where consciousness is lost and the jerking is sustained and rhythmic.
NOTE Myoclonic seizures are one type of seizure that can result in a "drop attack", other causes of drop attacks include tonic, atonic and myoclonic-atonic seizures.