[Two cases of unilateral chilblains associated with monoparesis]. / Engelures unilatérales associées à une monoparésie : 2 observations.

BACKGROUND: Chilblains are inflammatory dermal lesions associated with hypersensitivity to cold, and they occur on the extremities bilaterally and symmetrically. Their onset during the course of pro-thermogenic and autoimmune diseases has been widely reported, but the association with predisposing locoregional causes is not well known. PATIENTS AND METHODS: Case 1: a 57-year-old man, who smoked 80 packets per year, presenting a deficit of the levator muscles in his right foot following lumbar sciatica with paralysis of L5, consulted for unilateral necrotic lesions of the toes recurring each winter in the paralysed limb only. Case 2: a 60-year-old man had a previous history of liposarcoma of the right side treated with radiotherapy and surgery, resulting in sequelae of monoparesis and radiation-induced arteritis. Each winter, he presented recurring unilateral purpuric macules of the toes on his right foot, with no necrotic progression. In both cases, clinical examination, disease progression over time, histology and laboratory tests confirmed the diagnosis of idiopathic chilblains. CONCLUSION: The physiopathological hypotheses posited to account for the unilateral appearance of chilblains in the event of paralysis include decreased blood flow to the paralysed limb, imbalance in neuromodulators, dysfunction of the autonomous nervous system, cutaneous atrophy with hypertrophy of underlying soft tissues, and finally, hypoesthesia aggravating the trophic disorders.

Erythromelalgia.

Erythromelalgia is a rare syndrome characterized by the intermittent or, less commonly, by the permanent occurrence of extremely painful hyperperfused skin areas mainly located in the distal extremities. Primary erythromelalgia is nowadays considered to be a genetically determined neuropathic disorder affecting SCN9A, SCN10A, and SCN11A coding for NaV1.7, NaV1.8, and NaV1.9 neuronal sodium channels. Secondary forms might be associated with myeloproliferative disorders, connective tissue disease, cancer, infections, and poisoning. Between the pain episodes, the affected skin areas are usually asymptomatic, but there are patients with typical features of acrocyanosis and/or Raynaud's phenomenon preceding or occurring in between the episodes of erythromelalgia. Diagnosis is made by ascertaining the typical clinical features. Thereafter, the differentiation between primary and secondary forms should be made. Genetic testing is recommended, especially in premature cases and in cases of family clustering in specialized genetic institutions after genetic counselling. Multimodal therapeutic intervention aims toward attenuation of pain and improvement of the patient's quality of life. For this purpose, a wide variety of nonpharmacological approaches and pharmacological substances for topical and systemic use have been proposed, which are usually applied individually in a step-by-step approach. Prognosis mainly depends on the underlying condition and the ability of the patients and their relatives to cope with the disease.