Erythromelalgia: A Novel Mutation in SCN9A Causing Chronic Neuropathic Burning Feet Syndrome without Classic Skin Findings (P5.025)

Objective: To report a case of Erythromelalgia without classic skin findings. Background: Erythromelalgia, also known as red neuralgia is a condition caused by mutation of voltage-gated sodium channel (alpha subunit gene SCN9A ) . We report a case of erythromelalgia causing chronic neuropathic burning without classic skin changes. Introduction: A 43 years old African American man with a history of supposed juvenile myopathy and lactic acidosis was referred to Neurology clinic for burning feet for further diagnostic evaluation. Patient had a history of generalized muscle aches and burning in bilateral feet since childhood. Although he wanted to become a football player, the inability to tolerate shoes for a long time precluded this ambition. Gradually worsening symptoms since age 21 years (1990) eventually prompted him to seek further medical care. Carbamazepine effectively controlled the burning pain in the feet. Methods: Electromyography/nerve conductions and muscle biopsy performed at age 21 years of age (1990) were unremarkable. Onset of similar symptoms in the son by age 7 years (2014) prompted further work up to consider a genetic etiology, specifically, erythromelaglia. Results: A novel mutation of SCN 9A, c.733C>G (p.Leu245Val) , the gene implicated in erythromelalgia, that segregates only with the symptomatic individuals of his family. The patient, son, brother and nephew, all of whom were symptomatic, carried the same mutation. The characteristic redness and swelling was notably absent in our patient and his son. Discussion: The absence of the hallmark erythema and edema of the feet likely delayed diagnosis. This case illustrates the importance of considering erythromelalgia if there is a family history of similar symptoms even in the absence of typical features. Knowing the genetic diagnosis allows for prognostication, substantiates his diagnosis and improves overall outlook of his medical condition. Disclosure: Dr. Mankad has nothing to disclose. Dr. Konersman has nothing to disclose.