This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amyotrophic Lateral Sclerosis and other motor neuron diseases, Subject name: Medicine
Conduction velocity of nerves is NOT affected by which of the following? 
Select and explain. 
A. Leprosy, B. Motor neuron disease, C. Hereditary neuropathy, D. A.I.D.P
B: Motor neuron disease
Answer: B: Motor neuron disease 
Explanation: Motor neuron disease is at anterior horn cell, pyramidal neurons and not the nerves. Thus the conduction velocity in the nerves is normal. Leprosy - Affects nerves and both sensory nerve conduction /motor nerve conduction studies may demonstrate reduced amplitude in affected nerves but occasionally may reveal demyelinating features. Charcot-Marie-Tooth disease (CMT) -MC hereditary neuropathy and has reduced motor nerve conduction velocity A.I.D.P -Segmental demyelination in the spinal cord and peripheral nerves. Early features-prolonged F-wave latencies Prolonged distal latencies Reduced amplitudes of compound muscle action potentials, d/t involvements of nerve roots and distal motor nerve terminals