High-Resolution Ultrasonography of the Superficial Peroneal Motor and Sural Sensory Nerves May Be a Non-invasive Approach to the Diagnosis of Vasculitic Neuropathy

Abstract

High-resolution ultrasonography (HRUS) is an emerging new tool in the investigation of peripheral nerves. We set out to assess the utility of HRUS performed at lower extremity nerves in peripheral neuropathies. Nerves of 26 patients with polyneuropathies of different etiologies and 26 controls were investigated using HRUS. Patients underwent clinical, laboratory, electrophysiological assessment, and a diagnostic sural nerve biopsy as part of the routine work-up. HRUS was performed at the sural, tibial, and the common, superficial, and deep peroneal nerves. The superficial peroneal nerve longitudinal diameter (LD) distinguished best between the groups: patients with immune-mediated neuropathies (n = 13, including six with histology-proven vasculitic neuropathy) had larger LD compared to patients with non-immune-mediated neuropathies (p < 0.05) and to controls (p < 0.001). Among all subgroups, patients with vasculitic neuropathy showed the largest superficial peroneal nerve LD (p < 0.001) and had a larger sural nerve cross-sectional area when compared with disease controls (p < 0.001). Enlargement of the superficial peroneal and sural nerves as detected by HRUS may be a useful additional finding in the differential diagnosis of vasculitic and other immune-mediated neuropathies.

Keywords: nerve ultrasonography; peripheral neuropathy; superficial peroneal nerve; sural nerve; vasculitis.

Figure 1

The photographs in the upper row show the investigation sites of the reported peripheral nerves. In the middle row, an example for each nerve is given in the transverse sections and in the lower row in longitudinal sections. The nerves are marked with either cyan circles (transverse) or crosses (longitudinal).

Figure 2

Box-and-whisker plots illustrate the enlarged median cross-sectional area (CSA) in high-resolution ultrasonography (HRUS) of the sural nerves of patients with vasculitic neuropathy compared with disease controls (*p < 0.05).

Figure 3

Box-and-whisker plots illustrate the results of high-resolution ultrasonography (HRUS) of the superficial peroneal nerve in patients with neuropathies and disease controls; the longitudinal diameter (LD) is displayed in millimeter. (A) Patients with peripheral neuropathies have larger LD of the superficial peroneal nerve than disease controls. (B) The subgroup of patients with immune-mediated neuropathies (“immune NP”) has increased LD when compared to disease controls and to patients with non-immune-mediated neuropathies. (C) When separating vasculitic neuropathy from the group of other immune-mediated neuropathies, LD was largest, and also, when comparing vasculitic neuropathy with all other non-vasculitic neuropathies (“non-immune NP”) (D). *p < 0.05, **p < 0.01, and ***p < 0.001.