--are not only highly operator-dependent (they can vary considerably based on skill in placing the electrodes and needles, the temperature in the room and in the body being tested, etc.) but they can, of course, change over time, either due to worsening OR due to healing/re-enervation.

Still, a "normal" EMG/nerve conduction study does not rule out neuropathy. The damage may be patchy or changing, and such studies say nothing about dysfunction of the smaller, thinly myelinated or unmyelinated nerves, which are too thin to be measured by such studies.