Diagnostic utility of Sudoscan for detecting bortezomib-induced painful neuropathy: a study on 18 patients with multiple myeloma.

Introduction: In the past few years, treatment of multiple myeloma has undergone a deep change for the employment of novel treatment comprising proteasome inhibitors. Bortezomib is a first-line drug in therapy of multiple myeloma. The onset of peripheral neuropathy is a dose-limiting collateral effect of the drug. This neuropathy is a distal symmetric neuropathy that affects both large and small fibers. Nerve conduction study (NCS) can be used for the diagnosis of bortezomib neuropathy, but this technique demonstrates alterations of the large nerve fibers. Sudoscan is a novel technique utilized to offer an evaluation of sudomotor function. The main objective of this study was to compare the sensitivity and diagnostic specificity of Sudoscan with respect to the nerve conduction study after bortezomib treatment. Material and methods: A total of 18 multiple myeloma patients were studied, 10 (55.5%) men and 8 (44.5%) women. Patients were analyzed at baseline and after 6 months of treatment with bortezomib. Subjects were submitted to nerve conduction study and electrochemical skin conductance evaluation with the Sudoscan device. Patients were also submitted to a clinical measure of pain and neuropathy. Results: At baseline NCS showed that only the mean sural SAP amplitude was below the 2SD lower limit of normal in 3 (16.7%) patients, while at same time we found an alteration of Sudoscan profiles in 2 (11.1%) patients. After 6 months of treatment, the NCS profiles were altered in 13 (72.2%) patients, and the Sudoscan profiles were modified in 11 (61.1%) subjects. Conclusions: Our results suggest that Sudoscan can be considered for the diagnosis of bortezomib-induced neuropathy. It is objective, reproducible, and surely easier than the traditional nerve conduction study. Sudoscan may be a useful help to manage the therapeutic interventions in multiple myeloma.