Small fiber neuropathy as a possible cause for chronic pruritus

Abstract

Small fiber neuropathy arises from injury of small C and Aδ fibers and leads to pruritus as well as positive (pain, burning, tingling or stinging sensation) and negative neurological (numbness) symptoms. To give an overview on small fiber neuropathy as a cause for chronic pruritus, the diagnostic approach to this condition, and therapeutic options. A literature search using the terms "small fiber neuropathy", "pruritus", "itch", and "pain" was performed. Small fiber neuropathy is often associated with systemic diseases. However, it may occur without an underlying cause (idiopathic small fiber neuropathy). To identify small fiber neuropathy as the causal agent of pruritus, a detailed clinical history is essential. By measuring the intraepidermal nerve fiber density from skin biopsies at the sural nerve supplied region (lateral lower leg), the neurological impairment can be quantified. Often, dysfunction of a nerve fiber occurs after morphological changes ensue. Quantitative sensory testing allows the study of impaired function of these small fibers. Therapeutically, it is important to treat the underlying cause of the neuropathy. A symptomatic approach should be taken into account, when the cause cannot be treated. Topical capsaicin, as well as anticonvulsants and/or antidepressants, have been used with good results. Due to chronification processes, pruritus may persist even after treatment of the underlying cause. Therefore, early identification of small fiber neuropathy and immediate treatment of the cause is crucial for the success of the treatment.