Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) West syndrome ?
    ### Response:
    West syndrome is characterized by a specific type of seizure (infantile spasms) seen in infancy and childhood. This syndrome leads to developmental regression and causes a specific pattern, known as hypsarrhythmia (chaotic brain waves), on electroencephalography (EEG) testing.
    