A 39-Year-Old Woman with Intermittent Bilateral Foot and Leg Pain since Childhood

We describe a case of familial episodic pain syndrome with autosomal dominant inheritance that is caused by a gain-of-function mutation (Arg225Cys) in the SCN11A gene. In contrast to the phenotype of small fiber sensory neuropathy with mutations in voltage-gated sodium channels, our patient and her affected family members present with deep aching, mimicking fibromyalgia. In line with the feature of pain, patients respond well to non-steroidal anti-inflammatory drugs. Moreover, there is no detectable large or small nerve fiber degeneration. Together, these characteristics make the familial episodic pain syndrome clearly distinctive from small fiber sensory neuropathy.