Different iron deposition patterns in hemodialysis patients with and without restless legs syndrome: a quantitative susceptibility mapping study.

Objective: Brain iron deposition in hemodialysis (HD) patients increases over time. Iron deficiency in gray matter nuclei has been reported to lead to idiopathic restless legs syndrome (RLS) symptoms. Regardless of unpleasant RLS sensations, the patterns of iron deposition between hemodialysis patients with RLS (HD-RLS) and hemodialysis patients without RLS (HD-nRLS) are still unclear. To evaluate the differences in iron deposition patterns between HD-RLS and HD-nRLS patients, we utilized quantitative susceptibility mapping (QSM).

Methods: In sum, 24 HD-RLS patients, 25 HD-nRLS patients and 30 age- and sex-matched healthy controls (HCs) were enrolled. The QSM was used to assess susceptibility values of the regions of interest (ROIs), including the caudate nucleus (CN), putamen (PUT), globus pallidus (GP), thalamus (THA), substantia nigra (SN), red nucleus (RN) and dentate nucleus (DN).

Results: HD duration was significantly longer in HD-RLS patients than in HD-nRLS patients (P < 0.05). The susceptibility of HD-RLS and HD-nRLS patients in PUT was higher than that in HCs (P < 0.05), illustrating elevated iron content in the nucleus. Compared with HD-nRLS patients, HD-RLS patients demonstrated reduced susceptibility in CN and PUT (both P < 0.05). Compared with HCs, HD-RLS patients displayed decreased susceptibility in DN (P < 0.05).

Conclusions: Different iron deposition patterns between HD-RLS and HD-nRLS patients in PUT and DN, which further support disturbed sensory processing in RLS, may be involved in RLS pathogenesis in HD patients.