Corneal nerve quantification predicts the severity of symptoms in sarcoidosis patients with painful neuropathy

M. Brines, M. Swartjes, M.R. Tannemaat, A. Dunne, M. van Velzen, P. Proto, E. Hoitsma, I. Petropoulos, X. Chen, M. Niesters, A. Dahan, R. Malik (+1 others)
2013 TECHNOLOGY  
Small fiber neuropathy (SFN) is a debilitating condition characterized by chronic pain as well as sensory and autonomic dysfunction. SFN is an increasingly recognized component of a large number of diseases, including sarcoidosis. Although affecting an estimated 2{3% of the adult population in the United States, it often remains undiagnosed. Skin biopsy for evaluating intra-epidermal nerve fiber density (IENFD) and more recently corneal confocal microscopy (CCM) have been used to identify small
more » ... d to identify small fiber damage in patients with neuropathy. We demonstrate a significant reduction in IENFD, corneal nerve fiber number and length, with no change in the number of branches in patients with painful sarcoid neuropathy. Moreover, unlike IENFD, corneal nerve fiber number and length inversely correlate with the degree to which pain interferes with activities of daily living as assessed by the Brief Pain Inventory questionnaire. CCM thus constitutes an accurate, non-invasive assessment technique to aid in the diagnosis of SFN, as well as an objective marker of symptoms in patients with painful sarcoid neuropathy. INNOVATION Currently, a definitive diagnosis of small fiber neuropathy (SFN) requires a skin biopsy that demonstrates small nerve fiber loss. However, quantifying IENFD in skin biopsies is an invasive, laborintensive process that has a low sensitivity for diagnosing SFN and further does not correlate with the pain that patients report. Alternatively, CCM is a rapid non-invasive clinical ophthalmic technique for in vivo imaging and quantification of corneal nerve fibers. Here we show that CCM is a useful diagnostic tool to evaluate small fiber damage and that corneal nerve fiber density is inversely related to symptoms in patients with painful sarcoid neuropathy. This technology expands the role of CCM to one that provides a surrogate marker for both nerve fiber damage and pain in clinical trials of novel therapeutics in sarcoid and perhaps other painful small fiber neuropathies. Technology A R T I C L E S technology Downloaded from www.worldscientific.com by 69.125.224.29 on 09/30/13. For personal use only.
doi:10.1142/s2339547813500039 fatcat:s4vepvolzndtvlawkpvbxrbbhe