Which clinical features favor a myopathy over a neuropathy in a patient with weakness?

• A. Predominant proximal symmetric weakness with normal or near-normal reflexes early, marked fatigue, and elevated CK; EMG shows a myopathic pattern.
• B. Distal weakness with reduced reflexes and sensory loss.
• C. Wasting with fasciculations and widespread fibrillations.
• D. Hyperreflexia and spasticity.

Answer: (A)

When evaluating weakness, the pattern of muscle involvement and the accompanying signs help distinguish a primary muscle problem from a nerve problem. In a myopathy, the weakness is typically proximal and symmetric, affecting shoulder and hip girdle muscles first, with reflexes often preserved early in the course. The muscle injury itself leads to marked fatigue and a rise in serum creatine kinase. Electromyography then shows a myopathic pattern: small, short-duration motor unit potentials with early recruitment, rather than the denervation changes you’d expect from a neuropathy.

This combination—proximal symmetric weakness, relatively normal reflexes early, high CK, and a myopathic EMG pattern—best supports a primary muscle disease over a neuropathy.

By contrast, the other scenarios point toward nerve or motor-unit pathology: distal weakness with sensory loss and reduced reflexes fits a peripheral neuropathy; wasting with fasciculations and widespread fibrillations suggests motor neuron or denervation processes; hyperreflexia and spasticity indicate an upper motor neuron problem.