Langlois V, Bedat Millet AL, Lebesnerais M, Miranda S, Marguet F , et al.
La Revue de medecine interne •
Small fiber neuropathy (SFN) is still unknown. Characterised by neuropathic pain, it typically begins by burning feet, but could take many other expression. SFN affects the thinly myelinated Aδ and unmyelinated C-fibers, by an inherited or acquired mechanism, which could lead to paresthesia, thermoalgic disorder or autonomic dysfunction. Recent studies suggest the preponderant role of ion channels such as Nav1.7. Furthermore, erythromelalgia or burning mouth syndrome are now recognized as real SFN. Various aetiologies of SFN are described. It could be isolated or associated with diabetes, impaired glucose metabolism, vitamin deficiency, alcohol, auto-immune disease, sarcoidosis etc. Several mutations have recently been identified, like Nav1.7 channel leading to channelopathies. Diagnostic management is based primarily on clinical examination and demonstration of small fiber dysfunction. Laser evoked potentials, Sudoscan, cutaneous biopsy are the main test, but had a difficult access. Treatment is based on multidisciplinary management, combining symptomatic treatment, psychological management and treatment of an associated etiology.
Legroux-Crespel E, Sassolas B, Guillet G, Kupfer I, Dupre D , et al.
Annales de dermatologie et de venereologie •
Erythermalgia is a rare acrosyndrome characterized by reddening of the skin, local increase heat and pain. The disease is frequently resistant to treatment. Recently, Kuhnert et al. presented very favorable results using a combination of lidocaine and mexiletine. We used this treatment in 4 patients suffering from familial erythermalgia. In a family exhibiting severe familial erythermalgia involving 5 members over 3 generations, we treated 4 patients aged 41, 39, 19 and 15 years. In these patients, the erythermalgia known since early childhood, progressed in the form of multiple flares (6 to 7/day) during the day and at night, lasting several hours and often accompanied by headaches. The impact of the disease on their quality of life was major. Only cold-water baths provided temporary relief, obliging them to live with their "feet in cold water". After they had been informed of the modalities of treatment and in the absence of any contraindication, notably cardiologic, 200 mg (100 mg in the youngest patient) of lidocaine were infused in 4 hours in a single intravenous injection on the first day. Mixelitine was introduced on the second day at the dose of 600 mg in 3 oral intakes (200 mg in the youngest patient). The painful paroxistic symptomatology rapidly improved and the flares had disappeared on the 3dr day, thus permitting the progressive reduction in analgesics and major improvement in quality of life. This beneficial effect persisted with oral mexiletine alone, 2 years after the infusion of lidocaine in the first patient treated (and one year after in the other patients). Primary familial erythermalgia is highly resistant to treatment. The combined action of lidocain and mexiletine, usually well tolerated (class IB antiarrythmic), blocks the sodium channels. The mechanism of action of their analgesic effect is peripheral or central or even mixed. This benefit warrants confirmation in other forms of erythermalgia.