Neuropathic Itching Syndrome: a preliminary study

Icth is a common manifestation in systemic disease as malignancy, haematological disorders, uraemia and allergy. Microneurography studies showed that itch is mediated by a functionally distinct subset of C-fibres and dedicated neuronal pathways. We examined 6 patients (3 men and 3 woman, 55-72 years-old) complaining of itch at trunk and legs, with subacute onset, several years (1-10) before our first observation. In all itch was induced by ambient warm and was associated with a persisting burning-like heat sensation. Extensive dermatologic and allergologic investigations were unrevealing; treatment with anti-histaminergic and low-dosage oral steroids for several months did not modify the clinical picture. Physical examination was negative. Patients underwent clinical, laboratory examination, Neuropathy Pain Questionary, and nerve conduction studies (NCS). Small fibre impairment was investigated by skin biopsy at proximal thigh (Pth) and distal leg (Dl) and quantitative sensory testing (QST). Neurological examination showed the presence of thermal hypoesthesia in 3 pts, warm hyperalgesia in 3 pts. Laboratory investigations revealed only in one pt mild eosinophilia, in 1 patient neutrophilic leukocytosis, whereas chemistry profile, serum and urine immunofixation, screening for immunologic, infectious, and neoplastic disease in all was negative. Cerebrospinal fluid examination performed in 2 pts was normal. Nerve conduction studies and needle electromyography, was normal. Intraepidermal nerve fibre (IENF/mm) density was reduced in all patients, (pth 9,46/mm4,09; dl 5,04/mm2,51). Our preliminary data show the presence in this kind of pts with distinctive feature of itch and functional and histological impairment of small fibres, of itching Small Fiber Neuropathy.