Misery L

Small-fibre neuropathies and skin: news and perspectives for dermatologists.

Small-fibre neuropathies (SFNs) can be defined as diseases of small nerve fibres. Because their symptoms are mainly located in the skin in the initial stages, dermatologists may frequently be confronted with these diseases. Moreover, skin biopsies and the subsequent measurement of intraepidermal nerve fibre density have become a widely accepted technique to investigate the structural integrity of small nerve fibres. The pathogenesis of injury to small nerve fibres is poorly understood. It probably depends on the cause. SCN9A-gene variants have been reported. Diabetes mellitus is one of the main causes of SFNs. Some causes of SFNs are very well-known to dermatologists: Gougerot-Sjögren syndrome, lupus, sarcoidosis and Fabry disease. We also discuss erythermalgia, prurigo nodularis, nummular eczema, burning mouth syndrome and sensitive skin as SFNs.

Severe neurological complications of hereditary erythermalgia.

[Hereditary erythermalgia: a model for understanding erythermalgia?].

Treatment of familial erythromelalgia with venlafaxine.

[Aquadynia: a role for VIP?].

Aquadynia (water-related cutaneous pain) is a very rare disorder, recently described. A 40 year-old woman suffered from aquagenic pruritus, complicated by paresthesia and pain. There was no clinical argument in favor of a psychiatric disorder, Fabry's disease or any other disease. Clinical and histological cutaneous examinations were normal. Immunohistochemical study of neurotransmitters (substance P, calcitonin gene-related peptide or CGRP, vasoactive intestinal peptide or VIP, somatostatine) did not show any modification in nerve density. However, VIP-immunoreactive epidermal cells were observed. Electromyography and study of somesthesic-evoked potentials were normal. No treatment had provided any efficacy. Clonidine and capsaicin had been prescribed with partial success. Three other cases of aquadynia have been reported. Differential diagnoses of aquadynia are aquagenic pruritus and urticaria, hysteria or simulation, Fabry's disease, erythermalgia, peripheral neuropathy or polycythemia vera. The presence of VIP-immunoreactive cells suggests that VIP could be produced by these cells after contact with water. The effects of propanolol and clonidine on aquadynia are in favor of an adrenal component.

[Treatment of familial erythermalgia with the association of lidocaine and mexiletine].

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.