Erythromelalgia and Small Fibre Neuropathy

Today's post concerns another tongue twister of a name for an neurological condition associated with neuropathy. According to the dictionary, Erythromelalgia... is an affection of the feet and occasionally of the hands, characterized by burning pain and tenderness in the soles (or palms) attended with a purplish coloration. After reading this, don't be too worried, it is a relatively seldom seen version of small fibre neuropathy, although if you suffer from it that will be of little consolation. What is surprising is the fact that the symptoms many of us have, (burning feet, redness, sensitivity and sometimes swelling) are very close to the more extreme symptoms of Erythromelalgia. Logic suggests that there may be a link but I'll leave that for you to decide after reading the article which comes from dermnetnz.org (see link below). Certainly the treatment of Erythromelalgia is much the same as for peripheral neuropathy.

What is erythromelalgia?

Erythromelalgia is a condition characterised by intense burning pain, erythema (marked redness), and increased skin temperature, primarily of the feet and hands. The condition is classified into primary and secondary erythromelalgia. It has also been classified into early-onset and late-onset forms. Symptoms of the disease vary markedly between individuals; in some patients there is a continual burning pain while others experience “flare-ups” or bouts of the condition lasting from minutes to days.

Erythromelalgia is also known as ‘erythermalgia’. It may be considered a type of neuropathic pain syndrome (pain related to conditions affecting the nerves themselves), where there is dilation of the small blood vessels that become congested with blood.

What causes erythromelalgia and who gets it?

The actual cause of erythromelalgia is unknown in most cases. Primary erythromelalgia develops spontaneously without any associated underlying disease associated, and is sometimes called ‘idiopathic erythromelalgia’. Secondary erythromelalgia develops secondarily to medical conditions such as neurological diseases (e.g. multiple sclerosis, peripheral neuropathy), autoimmune diseases (e.g. lupus, diabetes mellitus), or more commonly the myeloproliferative disorders. In these disorders the bone marrow produces excessive numbers of cells, e.g. polycythaemia vera (increased red cells), and essential thrombocythaemia (increased platelets). Erythromelalgia presents before the appearance of the myeloproliferative disorder in 85% of cases.

People with early-onset erythromelalgia develop it before they are 25. Although the disease is of unknown origin in most cases, sometimes it can be traced back through generations of a family (Weir-Mitchell disease). This has recently been shown to be due to mutations in a gene called Na(v)1.7., which encodes a sodium channel within certain cells.
Late-onset erythromelalgia occurs most often around 40-60 years of age and is primary in about 60% of cases.
What are the signs and symptoms?

Lower extremities such as the soles of feet and toes are most commonly involved. Rarely does the pain extend up to include the knees. Upper extremity involvement includes the fingers and hands. Often both feet and hands are involved and both sides of the body (bilateral) are affected. It may affect one side of the body (unilateral), particularly in secondary cases. Less frequently, symptoms may also appear in the face, ears and other parts of the body.

The classic description of erythromelalgia is red, painful, warm hands or feet, brought on by warming or hanging the limb downward, and relieved with cooling and elevation.

■ Some patients notice a continual burning while others are troubled with “flare-ups”
■ Flare-ups may last minutes to days and typically occur late in the day and continue through the night
■ Usually attacks begin with an itching sensation, progressing to a more severe pain with a burning sensation
■ During an attack the affected extremity becomes warm, tender, swollen, and appears dusky red and sometimes mottled
■ Pain may be so intense that the patient cannot walk
■ Cooling (with fan or immersion in cold water) and elevating the extremity can relieve symptoms

Symptoms often become so bad that normal functioning and quality of life are greatly affected. Patients avoid warm weather and may even relocate to cooler climates. Many cannot wear socks or closed shoes even in winter. Some patients become virtually housebound by continuous flare-ups and pain.

How is the diagnosis made?

Investigation for underlying causes is essential in all new cases of the disease. Erythromelalgia may be an early sign of polycythaemia or thrombocythaemia, where symptoms may precede diagnosis of the myeloproliferative disorder by 2.5 years. Dramatic relief with aspirin is typical of this type and can be used as an aid to diagnosis.

Diagnosis is based fairly much on the clinical picture, hence is often difficult because of the intermittent nature of the disease. Provided the patient gives a good description of their symptoms, a tentative diagnosis may be made. If in doubt, immersing an affected area in hot water for 10-30 minutes may sometimes provoke an attack.

When no known underlying cause has been found, the erythromelalgia is considered primary.

What treatment is available?

The underlying cause must be treated where possible in secondary erythromelalgia. The treatment of symptoms of both primary and secondary erythromelalgia is through general non-medical measures, drug therapy and surgical intervention.
■ General non-medical measures such as cooling or elevating the extremity may relieve symptoms. Care is needed around cold water immersions, although it will provide temporary relief, it can cause many other serious problems. Frequent immersion into cold water can create a vicious cycle as the changes in temperature may cause reactive flaring. This can also lead to maceration of the skin, non-healing ulcers, infection, gangrene and amputation.
■ Topical treatment with capsaicin cream has been reported with varying results.
■ A variety of oral medications have been used to relieve symptoms, including: ■ Aspirin – promptly relieves symptoms of erythromelalgia involving myeloproliferative disorders
■ Serotonin re-uptake inhibitors – venlafaxine, sertraline, fluoxetine, paroxetine
■ Tricyclic antidepressants – amitriptyline, imipramine
■ Anticonvulsants – gabapentin
■ Calcium antagonists – nifedipine, diltiazem
■ Prostaglandins – misoprostol

■ Intravenous infusions of nitroprusside, lignocaine (lidocaine) and prostaglandin
■ Surgical sympathectomy (a procedure in which the sympathetic nerve fibres are selectively cut)

Patients respond quite variably to drug therapy and no single therapy has proved consistently effective. Spontaneous remissions have also been known to occur.

http://dermnetnz.org/vascular/erythromelalgia.html