Muscle relaxants and Neuro disease affecting response

[agammaglobulin]

I had a question regarding muscle relaxants and effects in neuro disease. I understand that in nerve injury (decrease ACh release), you get upregulation of ACh receptors causing increase sensitivity to Sux and decrease sensitivity to nondepol. The opposite is true in cases where you have decrease ACh Receptors (Myasthenia Gravis). I am doing some reading and Morgan and Mikhail has Lambert Eaten Syn (decrease Ach?) as increase sensitivity to BOTH sux and nondepol. For ALS they say increased sensitivity to nondep, which seems contrary to what you'd expect (decrease ACh release -->upregulation ACh R's-->decrease sens to nondep). Can anyone make sense out of this?

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[Ignatius J]

I had a question regarding muscle relaxants and effects in neuro disease. I understand that in nerve injury (decrease ACh release), you get upregulation of ACh receptors causing increase sensitivity to Sux and decrease sensitivity to nondepol. The opposite is true in cases where you have decrease ACh Receptors (Myasthenia Gravis). I am doing some reading and Morgan and Mikhail has Lambert Eaten Syn (decrease Ach?) as increase sensitivity to BOTH sux and nondepol. For ALS they say increased sensitivity to nondep, which seems contrary to what you'd expect (decrease ACh release -->upregulation ACh R's-->decrease sens to nondep). Can anyone make sense out of this?

My intuition tells me that ALS results in progressive muscle weakness so they would be very sensitive to relaxants regardless of how many receptors they have. That's how I look at it. Still have upregulated receptors so you worry about hyperkemia with sux.

Lambert-Eaton doesn't have proliferation of post junctional receptors thus the sensitivity to both.

Not sure if that answers your question or not.

 

[narcusprince]

This topic you just have to review from big Miller and just memorize the chart. It doesn't make a whole lot of sense. Clinically if I had someone with ALS, myasthenia, Lambert Eaton. I would avoid muscle relaxation altogether if possible. And look up the clinical condition before assuming care.