Nerve ultrasound in painful diabetic neuropathy: a pilot study of sural and tibial nerves

Abstract Background This case–control study investigated the role of nerve ultrasound measurement of the sural and tibial nerve cross-sectional area (CSA) in assessing painful diabetic neuropathy (PDN). It included 30 patients with PDN—15 with small fiber neuropathy (SFN) and 15 with mixed fiber neuropathy (MFN)—along with 15 healthy controls. Participants underwent standard nerve conduction studies including tibial and sural nerves, and nerve ultrasound of both nerves. Results Tibial nerve CSA was significantly higher in patients with MFN only compared to the control group. However, sural nerve CSA was significantly higher in both subgroups of PDN compared to the control group. Larger tibial and sural nerve CSA significantly correlated with lower tibial CMAP and CV, and sural SNAP, respectively, and both significantly correlated with lower IENFD in all subjects, but not in SFN patient group. The sural nerve CSA exceeding 2 mm 2 yielded a sensitivity of 60% and a specificity of 80% to diagnose SFN. Conclusions Sural nerve CSA may be enlarged in patients with PDN, even in its early stages of small fiber affection, while tibial nerve CSA enlargement may correlate with the more advanced MFN parameters.