Diffusion tensor MR neurography reveals altered sciatic and tibial nerve microstructure in chronic dialysis patients

Uremic polyneuropathy is a complication of chronic kidney disease, presenting as a distal symmetric neuropathy mainly attributed to axonal damage. Electrophysiology provides limited insight into microstructural nerve alterations. Magnetic resonance neurography (MRN) may enable assessment of peripheral nerve integrity. This study aimed to quantify sciatic and tibial nerve microstructural changes in chronic dialysis patients and evaluate their clinical relevance.

Thirty patients on chronic dialysis (DP)-without prediabetes or diabetes-and 30 healthy controls (HCs) underwent MRN, including diffusion tensor imaging (DTI). All MRN datasets of the distal thigh (30/30) were suitable for analysis. Four lower-leg examinations in the patient cohort (26/30) and three in the healthy group (27/30) were excluded because of motion artifacts. Fractional anisotropy (FA) was defined as the primary imaging outcome, while axial diffusivity (AD) and radial diffusivity (RD) were analyzed as secondary metrics. Electrophysiological testing was not available in four patients in the dialysis cohort (26/30). Results were compared between groups and correlated with electrophysiological, clinical, and laboratory findings.

FA of the sciatic (DP 0.44, HC 0.48, P < .001) and tibial nerve (DP 0.38, HC 0.43, P < .0001) and AD were significantly reduced in dialysis patients, while RD did not differ between groups. Lower FA correlated with electrophysiological measures, neuropathy scores, and was independently associated with group after adjustment for age, BMI, and sex. Subgroup analyses showed lower FA in patients fulfilling electrophysiological criteria for uremic polyneuropathy but no difference according to dialysis modality.

The reduction in FA and AD, together with electrophysiological and clinical correlations, is compatible with a predominantly axonal pattern of peripheral nerve involvement in chronic dialysis patients. DTI detected peripheral nerve microstructural alterations associated with chronic dialysis. These findings support further longitudinal and disease control studies to determine the clinical utility of DTI as an imaging biomarker in chronic dialysis patients.