Erythromelalgia [acromelalgia, Mitchell’s disease, red neuralgia, or erythermalgia] is a rare neurovascular peripheral nerve disorder in which blood vessels, usually in the lower extremities are episodically blocked and inflamed. This is associated with severe burning pain and skin redness associated with this blood vessel blockage.
The attacks are periodical and are commonly triggered by heat, pressure, mild activity, exertion, insomnia and stress.
Erythromelalgia can occur either as a primary or secondary disorder.
Primary erythromelalgia is caused by mutation of the voltage-gated sodium channel and is more common in males than females.
Secondary erythromelalgia may be associated with-
- Myeloproliferative disorders
- Medications: Like pergolide, bromocriptine, calcium channel blockers [nifedipine, felodipine, and nicardipine] and topical isopropanol.
- Poxvirus infection.
- Systemic lupus erythematosus
- HIV infection
- Diabetes mellitus
- Venous insufficiency
- Rheumatoid arthritis
- Mushroom poisoning
- Mercury poisoning
A genetic mutation and familial trend has also been observed.
Clinical Presentation of Erythromelalgia
Patient generally presents with red, painful, warm extremities which might have been exacerbated/aggravated by warming or dependency. Cooling may relieve the symptoms. The episodes may last minutes to days and the severity varies from an itching sensation in the beginning to severe pain with a burning quality. The lower limbs are more commonly affected than the upper limbs. Involvement is usually bilateral but my not be symmetric.
In case of secondary erythromelalgia associated with a myeloproliferative disorder, erythromelalgia usually precedes diagnosis of the myeloproliferative disorder.
Aspirin provides dramatic relief and can be used to aid in diagnosis.
The event is episodic in nature and patient might be absolutely fine between two episodes.
On examination during an episode, the affected extremity becomes warm, tender, and appears dusky, red, and sometimes mottled. The distal pulses in the limb might be normal or bounding. repeated episodes may leave ulcers.
Following pictures depict a case of erythromelalgia
A complete blood count can suggest presence of myeloproliferative disorder if present. Other investigations including radiographs are usually normal.
Investigations at most rule out presence of secondary causes but per se diagnosis of erythromelalgia is clinical. A high index of suspicion needs to be maintained.
Treatment of Erythromelalgia
Local measures, such as cooling or elevating the extremity, may relieve symptoms. In patients with myeloproliferative disorders, chemotherapy to reduce the platelet count may alleviate symptoms. Phlebotomy helps in some patients of polycythemia vara.
In addition the factors that can exacerbate the condition like heat exercise and dependent position for limbs should be avoided. Platelet inhibitors are useful in patients with thrombocytosis.
The optimal therapy in primary erythromelalgia is still unknown. Aspirin is usually the treatment of choice. Other NSAIDs provide relief of short duration.Medications those have been tried include lidocaine, mexiletine, prostacyclin and anagrelide.
Patients who respond to treatment aspirin have little morbidity but spontaneous remissions may occur. Early onset disease is associated with worse prognosis
Image Credit : Wikipedia
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