Erythromelalgia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Erythromelalgia is a condition characterized by episodes of pain, redness, and swelling in various parts of the body, particularly the hands and feet. These episodes are usually triggered by increased body temperature, which may be caused by exercise or entering a warm room. Ingesting alcohol or spicy foods may also trigger an episode. Wearing warm socks, tight shoes, or gloves can cause a pain episode so debilitating that it can impede everyday activities such as wearing shoes and walking. Pain episodes can prevent an affected person from going to school or work regularly.

The signs and symptoms of erythromelalgia typically begin in childhood, although mildly affected individuals may have their first pain episode later in life. As individuals with erythromelalgia get older and the disease progresses, the hands and feet may be constantly red, and the affected areas can extend from the hands to the arms, shoulders, and face, and from the feet to the entire legs.

Erythromelalgia is often considered a form of peripheral neuropathy because it affects the peripheral nervous system, which connects the brain and spinal cord to muscles and to cells that detect sensations such as touch, smell, and pain.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the SCN9A gene can cause erythromelalgia. The SCN9A gene provides instructions for making one part (the alpha subunit) of a sodium channel called NaV1.7. Sodium channels transport positively charged sodium atoms (sodium ions) into cells and play a key role in a cell's ability to generate and transmit electrical signals. NaV1.7 sodium channels are found in nerve cells called nociceptors that transmit pain signals to the spinal cord and brain.

The SCN9A gene mutations that cause erythromelalgia result in NaV1.7 sodium channels that open more easily than usual and stays open longer than normal, increasing the flow of sodium ions into nociceptors. This increase in sodium ions enhances transmission of pain signals, leading to the signs and symptoms of erythromelalgia. It is unknown why the pain episodes associated with erythromelalgia mainly occur in the hands and feet.

An estimated 15 percent of cases of erythromelalgia are caused by mutations in the SCN9A gene. Other cases are thought to have a nongenetic cause or may be caused by mutations in one or more as-yet unidentified genes.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Some cases of erythromelalgia occur in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some of these instances, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of erythromelalgia is unknown.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Peripheral neuropathy

Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.

Erythromelalgia

Recurrent episodes of redness, burning pain, and warmth of the extremities following exposure to heat or exercise with symptoms predominantly involving the feet.

Triggered by

A trigger is defined as an external factor that leads to the manifestation of a sign or symptom in a person with a susceptibility to developing that manifestation.

Affected

This term applies to a family member who is diagnosed with the same condition as the individual who is the primary focus of investigation (the proband).

Which doctor should you see?

The suggested department for discussing Erythromelalgia is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Erythromelalgia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.