Erythromelalgia

Synonyms

4

Overview

Erythromelalgia is a rare disorder in which blood vessels, usually in the lower extremities, are episodically blocked and inflamed. It 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. This condition may occur spontaneously (primary EM) or secondary to neurological diseases, autoimmune diseases, or myeloproliferative disorders (secondary EM). 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.

Symptoms

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.

Causes

Currently it is very difficult to predict how a person's primary erythromelalgia will affect them overtime. The cause of primary erythromelalgia is not well understood. Much of the literature regarding the long term outlook for people with idiopathic primary erythromelalgia is compiled from individual case reports. Erythromelalgia is usually a chronic or persistent condition, however there have been cases that have fully resolved with time. Many people with primary erythromelalgia have stable symptoms, however cases of progressive disease (symptoms worsening overtime) have also been described. Pain is a characteristic/classic feature of primary erythromelalgia. Unfortunately we were not able to find information specific to painless cases of this disorder, and outcomes of these individuals.

About 15% of cases of erythromelalgia are caused by mutations in the SCN9A gene. The SCN9A gene gives instructions for making part of a sodium channel which carries sodium into cells and helps them make and transmit electrical signals. These sodium channels are found in nerve cells that transmit pain signals to the spine and brain. Mutations that cause erythromelalgia cause increased transmission of pain signals, leading to the signs and symptoms of the condition. In some of these cases, an affected individual inherits the mutation from an affected parent. In other cases, a new mutation occurs for the first time in an individual with no history of the condition in the family.

In the remainder of cases, the exact underlying cause is not currently known. Evidence suggests that it results from abnormalities in the normal narrowing and widening of certain blood vessels, leading to abnormalities in blood flow to the hands and feet. There may be a variety of non-genetic causes, or mutations in other genes that have not yet been identified.

Diagnosis

Erythromelalgia can be diagnosed through a clinical exam and medical history. Additional tests may include a skin biopsy and thermography to evaluate skin temperature. Blood tests or other studies may be done to rule out other conditions that can cause similar symptoms.

There is not a specific type of doctor that always diagnoses and treats erythromelalgia. A variety of specialists (alone or in combination) may be involved in the diagnosis and treatment of this condition. These may include vascular specialists, hematologists, dermatologists, neurologists, rheumatologists, and other types of physicians. The type of specialist that is appropriate may depend on the underlying cause when secondary erythromelalgia is present. Since erythromelalgia is a rare disease, many doctors are not familiar with the condition. The Erythromelalgia Association offers resources and support for individuals looking for more information about the diagnosis of the condition.

Erythromelalgia is sometimes caused by other disorders. A partial list of diseases known to precipitate erythromelalgia is below.

• Myeloproliferative disease
• Hypercholesterolemia
• Autoimmune disorder
• Small fiber peripheral neuropathy
• Fabry's disease
• Mercury poisoning
• Mushroom poisoning
• Obstructive Sleep Apnea
• • Sciatica

Prognosis

Avoiding triggers is key to the management of current symptoms, but little is known regarding how this affects the long-term course of an individual's condition.

Treatment

Treatment depends on the underlying cause and may include topical and/or oral medications. In some cases, the condition goes away without treatment. There appear to be several subtypes of erythromelalgia and different subtypes respond to different therapies. Treatment consists of a trying various approaches until the best therapy is found. Patients respond quite variably to drug therapy and no single therapy has proved consistently effective. Spontaneous remissions have also been known to occur.

Drugs shown to be effective in relieving pain in some individuals include: aspirin, prostaglandins (misoprostol), serotonin-norepinephrine reuptake inhibitors (venlafaxine and sertraline) and selective serotonin reuptake inhibitors (SSRIs), anticonvulsants (gabapentin), sodium channel blockers, carbamazepine, tricyclic antidepressants (amitriptyline and imipramine), calcium antagonists (nifedipine and diltiazem), magnesium, sodium nitroprusside infusion, and cyclosporine. Other treatments include: cooling or elevating the extremity, topical treatment with capsaicin cream, and surgical sympathectomy (a procedure where the sympathetic nerve fibers are selectively cut).Avoidance of triggers (such as warmth, prolonged standing, etc.) may reduce the number or severity of flare ups.

Resources

• NIH
• Mayo Clinic
• Genetics Home Reference