Normal regional brain iron concentration in restless legs syndrome measured by MRI

Susanne Knake¹, Johannes T Heverhagen², Katja Menzler¹, Boris Keil², Wolfgang H Oertel¹, Karin Stiasny-Kolster¹

¹Department of Neurology, Center of Nervous Diseases, ²Department of Radiology, Philipps University, Marburg, Germany

Abstract: Using a T₂* gradient echo magnetic resonance imaging (MRI) sequence, regional T₂ signal intensity (SI) values, a surrogate marker for T₂ values, were determined in 12 regions of interest (substantia nigra, pallidum, caudate head, thalamus, occipital white matter, and frontal white matter bilaterally) and in two reference regions (cerebrospinal fluid and bone) in 12 patients suffering from moderate to severe idiopathic restless legs syndrome (RLS; mean age 58.5 ± 8.7 years) for 12.1 ± 9.1 years and in 12 healthy control subjects (mean age 56.8 ± 10.6 years). Iron deposits shorten T₂ relaxation times on T₂-weighted MRI. We used regional T₂* SI to estimate regional T₂-values. A T₂-change ratio was calculated for each region of interest relative to the reference regions. We did not find significant differences in any of the investigated brain regions. In addition, serum measures involved in iron metabolism did not correlate with T₂ SI values. We could not replicate earlier findings describing reduced regional brain iron concentrations in patients with RLS. Our results do not support the view of substantially impaired regional brain iron in RLS.

Keywords: restless legs syndrome, pathophysiology, iron, MRI, substantia nigra