MRI evaluation of Pacinian corpuscle number and distribution in the forefoot in diabetic sensorimotor polyneuropathy

Abstract

Abstract Objectives To evaluate Pacinian corpuscles (PC) in the forefoot of patients with type 2 diabetes-derived sensorimotor polyneuropathy (DSP) with MRI. Materials and methods This single-center study compared 20 DSP patients who underwent clinical forefoot 3-T MRI to healthy volunteers matched for age and gender. Two radiologists independently assessed the number and distribution of PC. In addition, one radiologist determined PC size. Correlations between PC number, duration of diabetes, and Hemoglobin A1c (HbA1c) were assessed. Results In DSP patients, the number of PC in the forefoot was significantly reduced compared to healthy volunteers (82.7 ± 46.1 vs. 265.3 ± 49.3, p < 0.001). In contrast to the typical “chain-like” pattern of PC in healthy volunteers, their arrangement was heterogeneous in DSP patients and showed a more isolated “spot-like” pattern. Volunteers exhibited the highest PC number along the proximal phalanges, followed by the metatarsophalangeal (MTP) joints, while in patients, no such predominance was found. In DSP patients, the maximum diameter of PC was 3 mm (range 1–3 mm) compared to 5 mm (1–5 mm) in healthy volunteers. In patients, the mean duration of diabetes was 234.8 ± 130.4 months, and the mean HbA1c was 7.6 ± 1.1%. There was no significant correlation between PC number, duration of diabetes, and HbA1c. Conclusion DSP patients had threefold lower PC numbers in the forefoot and exhibited a “spot-like” PC distribution pattern rather than the typical “chain-like” pattern observed in healthy volunteers. The exact depiction of PC and their distribution in the forefoot opens up the possibility of using MRI as a noninvasive diagnostic tool to assess DSP. Critical relevance statement MRI may serve as a noninvasive diagnostic tool for assessing patients with diabetic sensorimotor polyneuropathy as it allows for evaluating Pacinian corpuscle number and distribution in the forefoot. Key Points DSP patients showed three times lower forefoot PC numbers than healthy volunteers. PC distribution was altered in DSP patients and termed a “spot-like” pattern. Reduced PC (n < 9 along each MTP joint II-V) might be suspicious for DSP. Graphical Abstract

Keywords

• Pacinian corpuscle
• MRI
• Diabetes
• Diabetic sensorimotor polyneuropathy