August 17, 2015: “Nav”igating painful neuropathies
August 17, 2015
“Nav”igating painful neuropathies
Neuropathic pain is a common reason for referrals to neurology clinics. There is increasing evidence to support involvement of sodium channels in painful, small-fiber, neuropathies. Small-fiber neuropathies affect the myelinated A-fibers and unmyelinated C-fibers, resulting in pain and associated autonomic features. The voltage-gated sodium channels, Nav1.7 to 1.9, are preferentially found in the peripheral nervous system and are involved with the generation and propagation of action potentials in the nociceptive pathways. These channels, encoded by the SCN9A, SCN10A and SCN11A genes, are expressed within the dorsal root and autonomic ganglia. Mutations in these genes often lead to gain-of-function and increased firing rates or lowered thresholds within the dorsal root ganglion. Mutations in the Nav1.7 channel are associated with inherited erythromelalgia, characterized by recurrent attacks of symmetric intense pain, erythema, warmth, and swelling of the feet. Further expansion of the understanding of sodium channelopathies and their association with small-fiber neuropathies will help lead to better treatment options.
- Brouwer BA, Merkies IS, Gerrits MM, Waxman SG, Hoeijmakers JG, Faber CG. Painful neuropathies: the emerging role of sodium channelopathies. Journal of the Peripheral Nervous System 2014; 19: 53-65.
Submitted by James Addington, M.D. Resident Physician, Department of Neurology, University of Virginia.
Disclosures: Dr. Addington is a member of the Residents & Fellows Section of Neurology