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.

However, the study is retrospective and only a small number of patients could be identified. Several points therefore need to be clarified or confirmed in a second prospective study.

In and out patients evaluated for a sensory neuropathy meeting the inclusion and non-inclusion criteria will be proposed to enter the study

At inclusion the SSN diagnostic score is calculated and a blood sample is tested for anti-FGFR3 antibody.

Follow up: Patients positive for anti-FGFR3 antibodies will be followed and evaluated clinically and electrophysiologically at 1, 6 and 12 months. A blood sample is taken at 6 and 12 months.

A subgroup of patients negative for anti-FGFR3 antibodies will be randomly selected for evaluation at 1, 6 and 12 months.

Inclusion Criteria:

• A :Patients Male or female patient aged 18 years or more

Patients with a clinically pure sensory peripheral neuropathy including :

• idiopathic or dysimmune sensory neuronopathies
• idiopathic or dysimmune distal axonal sensory neuropathy
• sensory chronic inflammatory demyelinating polyradiculoneuropathy
• idiopathic or dysimmune small fiber neuropathies
• idiopathic or dysimmune trigeminal nerve neuropathy
• positive to antibodies anti-FGFR3

B :Controls Male or female patient aged 18 years or more

Patients with a clinically pure sensory peripheral neuropathy including :

• idiopathic or dysimmune sensory neuronopathies
• idiopathic or dysimmune distal axonal sensory neuropathy
• sensory chronic inflammatory demyelinating polyradiculoneuropathy
• idiopathic or dysimmune small fiber neuropathies
• idiopathic or dysimmune trigeminal nerve neuropathy
• negative to antibodies anti-FGFR3

Exclusion Criteria:

• -Motor or sensory-motor neuropathies
• Genetic, toxic, paraneoplasic neuropathies
• Diabetic Neuropathy.
• Neuropathy with Anti-MAG or anti-ganglioside IgM.
• Pregnant or breastfeeding woman

Patient group : patient with clinically pure sensory peripheral neuropathy and positive for anti-FGFR3 antibodies Control group :clinically pure sensory peripheral neuropathy and negative for anti-FGFR3 antibodies