Question:hard
All of the following statements about the neuromuscular blockade produced by succinylcholine are true, except:
All of the following statements about the neuromuscular blockade produced by succinylcholine are true, except:
Show Hint
Fade is the signature of a non-depolarising block, not a pure depolarising one.
Updated On: Jun 24, 2026
- No fade on train of four stimulation
- Fade on tetanic stimulation
- No post tetanic facilitation
- Train of four ratio > 0.4
Show Solution
The Correct Option is B
Solution and Explanation
The trick here is that succinylcholine causes a depolarising (phase I) block, and a depolarising block behaves like a steady, even weakening of every response rather than a progressive collapse.
Run through the monitoring signs. On a train of four, all four twitches shrink together with no fade, so the no-fade statement is correct. After a tetanic burst there is no boost to the next twitch, so the no post-tetanic-facilitation statement is also correct. The train of four ratio stays high, comfortably above 0.4, so that statement is correct too.
The one that does not belong is fade on tetanic stimulation. Fade, whether on the train of four or on tetanus, is the hallmark of a non-depolarising block (or a phase II block), where acetylcholine release cannot keep up. A clean depolarising block holds its tetanic response without fading.
Since the stem asks for the exception, the false statement is the fade on tetanic stimulation.
\[\boxed{\text{Fade on tetanic stimulation}}\]
Run through the monitoring signs. On a train of four, all four twitches shrink together with no fade, so the no-fade statement is correct. After a tetanic burst there is no boost to the next twitch, so the no post-tetanic-facilitation statement is also correct. The train of four ratio stays high, comfortably above 0.4, so that statement is correct too.
The one that does not belong is fade on tetanic stimulation. Fade, whether on the train of four or on tetanus, is the hallmark of a non-depolarising block (or a phase II block), where acetylcholine release cannot keep up. A clean depolarising block holds its tetanic response without fading.
Since the stem asks for the exception, the false statement is the fade on tetanic stimulation.
\[\boxed{\text{Fade on tetanic stimulation}}\]
Was this answer helpful?
0
