What is the difference between an emg/ncv of a patient with upper motor neuron disorder, and another with lower motor neuron disorde?

PNS versus CNS: Electromyography & nerve conduction studies evaluate the peripheral nervous system (PNS), of which lower motor neurons are part. Upper motor neurons belong to the central nervous system (CNS) & must be evaluated by other means. Someone with an upper motor neuron disorder will have normal or nonspecific EMG/NCV findings, whereas someone with a lower motor neuron disorder will have abnormal EMG/NCS.