Small fibre neuropathy in patients with chronic pain and a previous diagnosis of Multiple Chemical Sensitivity syndrome

Abstract Small fiber neuropathy (SFN) is characterised by an involvement of Aδ and C-fibres leading to sensory, mainly pain, and/or autonomic symptoms. Multiple chemical sensitivity syndrome (MCS) is a still not fully defined condition characterised by the arising of different symptoms after exposure to several chemical substances. Pain is often complained by patients affected by MCS. In this study we report the histological and clinical data of a cohort of patients referred to our attention for the suspect of SFN because of chronic pain, who had also received a previous diagnosis of MCS. We studied a total of 21 patients; all patients underwent neurological clinical examination (including scales for pain and autonomic disorders) and skin biopsy. Age matched healthy were used as controls for skin biopsy data. In addition, nerve conduction studies and serum screening to exclude possible causes of peripheral neuropathy were also performed. Skin biopsy disclosed a somatic SFN in all patients. Notwithstanding the majority (18 out of 21) of patients complained also of autonomic symptoms we found a sparing of autonomic innervation on skin biopsy. Chronic pain in MCS could be secondary to the presence of a somatic SFN although larger studies are needed to confirm our observation.