A tentative interpretation of electromyographic regional differences in bulbar and limb onset ALS

Electromyography (EMG) could be useful in defining regional motor neuron vulnerability in ALS. We performed EMG in 36 sporadic ALS patients (9 with bulbar-onset and 27 with limb-onset symptoms). Active denervation was more frequent in limb than in corresponding paraspinal muscles, in the thoracic paraspinal, and in the bulbo-cervical muscles in patients with bulbar-onset symptoms. These results are consistent with a regional motor neuron vulnerability along with a nerve length-dependent liability.