We propose to explore the central aspects (somatosensory evoked potentials, SEPS, and transcranial magnetic stimulation, TMS) in patients with upper limb disorders, because the cortical representation of hand muscles is easier to study than the lower limb muscle representations. In contrast, the peripheral studies (quantitative EMG and nerve conduction) will be performed in patients with lower limb disorders, due to length, accessibility and separation of pure motor and sensory nerves in the leg.