Abnormal warm and cold sensation thresholds suggestive of small-fibre neuropathy in sarcoidosis

Objective: A substantial number of sarcoidosis patients report apparently non-specific symptoms such as pain, for which no organic substrate has yet been found. Recently we observed symptoms suggestive of small-fibre neuropathy in a group of sarcoidosis patients. The aim of the present study was to verify this observation using various electrophysiological tests. Methods: In 74 sarcoidosis patients complaining of symptoms suggestive of small-fibre neuropathy, thresholds for warm (WS) and cold sensation (CS) as well as for heat pain were determined at the thenar eminence and the foot dorsum. Furthermore, sympathetic skin responses (SSR), nerve conduction studies and concentric needle electromyography were performed. In 31 patients, cardiovascular autonomic testing was carried out. Results: Thermal threshold testing (TTT) revealed abnormalities in 51 of the 74 patients. Abnormalities showed an asymmetrical distribution. WS was affected more often than CS and feet more often than hands. Nerve conduction studies in the legs showed slightly abnormal results in 6 patients; all of these had abnormal TTT results. The SSR was absent at the foot in 7 patients. Cardiovascular autonomic testing was abnormal in only a single patient. Conclusions: In a subgroup of sarcoidosis patients we found TTT abnormalities suggestive of small-fibre neuropathy. SSR and cardiovascular autonomic testing appeared to be of little diagnostic value. Small-fibre neuropathy may be the cause of a number of hitherto unexplained symptoms in sarcoidosis.