About Inherited Erythromelalgia
Inherited erythromelalgia is caused by gain-of-function mutations in SCN9A, the gene encoding the Nav1.7 voltage-gated sodium channel expressed primarily in pain-sensing neurons of the dorsal root ganglia. These mutations lower the activation threshold of the channel and slow its deactivation, causing peripheral nociceptive neurons to fire excessively in response to normally tolerable warmth. The resulting neuronal hyperexcitability produces the characteristic burning pain, while sympathetic dysregulation causes localized vasodilation, redness, and warmth in the extremities.
Episodes are typically triggered by increased body temperature from exercise, warm environments, or wearing closed shoes. Patients often develop elaborate cooling behaviors to manage pain, including prolonged cold water immersion, which can itself cause tissue damage. The condition is distinct from secondary erythromelalgia, which occurs as a complication of myeloproliferative disorders or other conditions. Diagnosis is confirmed through genetic testing for SCN9A mutations. Current treatment is largely empirical, with sodium channel blockers like mexiletine showing benefit in some patients. Kv7 potassium channel openers represent a newer therapeutic approach being studied in clinical trials.
Common Symptoms of Inherited Erythromelalgia
Recognizing the signs of Inherited Erythromelalgia early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Recurrent episodes of intense burning pain in the feet, hands, or both
- Visible redness (erythema) during pain episodes
- Warmth and swelling of affected extremities
- Pain triggered or worsened by heat, exercise, warm environments, or standing
- Symptom relief from cooling (cold water, ice packs, fans)
- Episodes lasting minutes to hours, sometimes days
- Skin damage from repeated cold immersion to relieve pain
- Sleep disruption due to nighttime flares
- Progressive worsening of episodes over years in some patients
- Potential spread from feet to hands and other extremities over time
Who Inherited Erythromelalgia Affects
Inherited erythromelalgia typically presents in childhood or early adolescence, with a median age of onset around 10 years. The condition follows autosomal dominant inheritance, meaning an affected parent has a 50% chance of passing the mutation to each child.
Males and females are affected equally. There is significant variation in severity even within the same family carrying the same SCN9A mutation. The condition occurs across all ethnic groups with no known predilection.
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