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.