Dysimmune sensory neuropathies: Diagnostic and therapeutic issues

Sensory neuronopathies or ganglionopathies (SNN) are rare diseases inducing the destruction of sensory neurons in the dorsal root ganglia and resulting in severely disabling ataxia and pain. They involve toxic, viral, genetic or dysimmune processes, but almost half of the cases remain idiopathic. Dysimmune SNN, which could represent half of the cases, include paraneoplastic SNN, SNN associated with systemic autoimmune diseases such as Sjogren syndrome or isolated cases. Cytotoxic T-cells are probably the main effectors of the immune response. As potentially treatable, these disorders are important to identify. The main issue is to obtain an early diagnosis since the therapeutic window before neuronal death is narrow. The availability of diagnostic biomarkers is thus crucial. Onconeural antibodies such as the anti-Hu antibody highly specific for paraneoplastic SNN are typically what we need. Recent advance using proteomic methods allowed the identification of anti-FGFR3 and anti-AGO antibodies as biomarkers of potentially dysimmune non-paraneoplastic SNN. In two third of the cases they were the only indicators of an associated autoimmune process. Other antibodies are probably to discover. They open the way to the development of clinical trials in dysimmune SNN. (C) 2021 l'Academie nationale de medecine. Published by Elsevier Masson SAS. All rights reserved.