Question 14.1

In each part of this question, list clinical examination findings for each of the two underlined conditions that would help you to distinguish between them:

A myopathy or a neuropathy as being the cause of weakness in all limbs of a patient

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College Answer

Myopathy

Wasting is late sign
Usually proximal weakness
Reflexes preserved until late
Normal sensory exam
May be muscle tenderness

Neuropathy

Wasting earlier
May be fasciculations
Often peripheral distribution
Loss of reflexes
May be abnormal sensory exam

Discussion

This comes down to basic common sense.

If the nerves are healthy, and the muscles are to blame,

The sensory supply should be preserved
The reflexes should be preserved
Weakness should be proximal - that is where the bigger muscles are, and the weakness there will be more obvious.
There should be no fasciculations

Also...

There may be myocardial involvement (skeletal myopathies tend to be associated with cadiomyopathy)
The muscles involved may be painful and tender(as in myositis)

This question has been repeated. Its doppelganger, Question 3.1 from the first paper of 2010, has a much better-organised college answer.

References

Chapter 57 (pp. 617) Neuromuscular diseases in intensive care by George Skowronski and Manoj K Saxena

UpToDate: An approach to the patient with muscle weakness

Young, G. Bryan, and Robert R. Hammond. "A stronger approach to weakness in the intensive care unit." Critical care 8.6 (2004): 416.

Dhand, Upinder K. "Clinical approach to the weak patient in the intensive care unit." Respiratory care 51.9 (2006): 1024-1041.

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