Sensory neuronopathies affect sensory neuron in the posterior spinal ganglion. They are responsible for pain, balance disorder (ataxia) and the use of hands. They depend on multiple etiologies. In a retrospective study, the investigators showed that the anti-FGFR3 antibody is a diagnostic marker of a subset of sensory neuronopathies. The investigators believe that other antibodies can be discovered in patients who remain seronegative changing.