title: Identifying a therapeutic window in acute and subacute inflammatory sensory neuronopathies.
abstract: BACKGROUND
  Patients with inflammatory sensory neuronopathy (SNN) may benefit from immunomodulatory or immunosuppressant treatments if administered timely. Knowing the temporal profile of neuronal loss in dorsal root ganglia will help to ascertain whether a final diagnosis may be reached before the occurrence of irreversible neuronal injuries. Thus, we addressed the evolution of neuronal loss in SNN by using sensory nerve action potentials (SNAPs) as a surrogate marker of neuron degeneration.
  
  
  METHODS
  Eighty-six patients with acute/subacute inflammatory SNN (paraneoplastic, associated with dysimmune diseases, or idiopathic) were retrospectively studied. The monthly SNAP reduction was determined and normalized with the lower limit of normal. Disability progression was expressed by the modified Rankin score and correlated with SNAP reduction.
  
  
  RESULTS
  The monthly SNAP reduction was similar in the four limbs although the median nerve was less severely affected. The monthly SNAP reduction was very severe within the first two months of evolution, began to slow down after seven months, and stabilized after ten months. It was tightly correlated with disability progression. Kaplan-Meier analysis showed that the median time until matching the diagnostic criteria of SNN was 8.5 months. Within this period, 42% of nerves remained excitable.
  
  
  CONCLUSIONS
  Developing treatment aiming at the stabilization of SNN is possible within the first 8 months of evolution. An improvement of the disease is possible if patients are treated within two months, which needs an early referral to an expert center and ENMG testing of the radial and ulnar nerves, which are most sensitive to changes.
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares Rhône-Alpes, CHU de Saint-Etienne, France; Université de Lyon, Saint-Etienne, France; INSERM U1028, Centre des Neurosciences de Lyon, Lyon, France. Electronic address: j.christophe.antoine@chu-st-etienne.fr.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Antoine
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares Rhône-Alpes, CHU de Saint-Etienne, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Robert-Varvat
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares, Hôpital de la Salpêtrière, Paris, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Maisonobe
authors.affiliation: Service de Neurologie, Hôpital Henri Mondor, Créteil, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Créange
authors.affiliation: Centre de Référence des Maladies Neuromusculaires et de la SLA, Hôpital de La Timone, Marseille, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Franques
authors.affiliation: Service de Neurologie, CHU de Poitiers, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Mathis
authors.affiliation: Centre de Référence des Maladies Neuromusculaires et de la SLA, Hôpital de La Timone, Marseille, France.
authors.forename: Emilien
authors.initials: E
authors.lastname: Delmont
authors.affiliation: Unité Nerf-Muscle, Service de Neurologie, Département des Neurosciences Cliniques, Centre Hospitalier Universitaire Vaudois, Université de Lausanne, Lausanne, Switzerland.
authors.forename: Thierry
authors.initials: T
authors.lastname: Kuntzer
authors.affiliation: Service de Neurologie, Hôpital Henri Mondor, Créteil, France.
authors.forename: Jean-Pascal
authors.initials: JP
authors.lastname: Lefaucheur
authors.affiliation: Centre de Référence des Maladies Neuromusculaires et de la SLA, Hôpital de La Timone, Marseille, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Pouget
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares, Hôpital de la Salpêtrière, Paris, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Viala
authors.affiliation: Centre de Référence des Maladies Neuromusculaires et SLA, CHU de Nice, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Desnuelle
authors.affiliation: Service de Neurologie, CHU de Strasbourg, France.
authors.forename: Andoni
authors.initials: A
authors.lastname: Echaniz-Laguna
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares Rhône-Alpes, CHU de Saint-Etienne, France.
authors.forename: Francesco
authors.initials: F
authors.lastname: Rotolo
authors.affiliation: Centre de Référence Maladies Neuromusculaires Rares Rhône-Alpes, CHU de Saint-Etienne, France; Université de Lyon, Saint-Etienne, France; INSERM U1028, Centre des Neurosciences de Lyon, Lyon, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Camdessanché
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D005260:Female; D005727:Ganglia, Spinal / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000503:physiopathology; D012189:Retrospective Studies; D014459:Ulnar Nerve / Q000503:physiopathology
keywords: Diagnosis; Evolution; Sensory action potentials; Sensory ganglionopathy; Sensory neuronopathy