This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
Train of four fade is a characteristic feature of: 
Select and explain. 
A. Depolarizing block, B. Non depolarizing block, C. Both depolarizing and non-depolarizing block, D. Malignant hypehermia
B: Non depolarizing block
Answer: B: Non depolarizing block 
Explanation: Train of four fade is a characteristic of a non-depolarizing block. The Train-of-four stimulation denotes the administration of four successive 200-ps stimuli in 2 seconds (2 Hz) and a series of patterns are produced and these patterns differ in a depolarizing block differs from that of a non-depolarizing block. In a non-depolarizing block there is progressive depression of height with each twitch (fade) and in a depolarizing block there is equal depression of all four twitches (No fade). Ref: Clinical Anesthesiology By G. Edward Morgan, 4th Edition, Pages 152, 209