Evidence map›Paper›PMID 27544840›Full record

ArticleSleep medicine2016

Brain iron deficiency in idiopathic restless legs syndrome measured by quantitative magnetic susceptibility at 7 tesla.

Xu Li, Richard P Allen, Christopher J Earley, Hongjun Liu, Tiana E Cruz, Richard A E Edden, Peter B Barker, Peter C M van Zijl

Open access · greenAbstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Sleep medicine, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 39 papers, 2 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
39citing papers in PubMed, 2 pooled it
8.8field-weighted citation impact, top 2% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

39 citing papers in PubMed, 2 syntheses or guidelines pooled it, 86 citations in OpenAlex.

  1. Putative Animal Models of Restless Legs Syndrome: A Systematic Review and Evaluation of Their Face and Construct Validity.Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics · 2023
    Pooled it
  2. Pooled it
  3. Trial
  4. Trial
  5. Altered iron metabolism and iron therapy in restless legs syndrome.Journal of neural transmission (Vienna, Austria : 1996) · 2026
    Review
  6. The evolving treatment landscape of restless legs syndrome.Therapeutic advances in neurological disorders · 2026
    Review
  7. Review
  8. Article
  9. Sleep Medicine-What's in a Name?Journal of sleep research · 2025
    Review
  10. Article
  11. Article
  12. Article
  13. Article
  14. MRI findings in movement disorders and associated sleep disturbances.American journal of nuclear medicine and molecular imaging · 2023
    Review
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  16. Article
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors at 2 institutions in 2 countries.

Xu LiF.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. Electronic address: xuli@mri.jhu.edu.
Richard P AllenDepartment of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Christopher J EarleyDepartment of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Hongjun LiuF.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, Guangzhou, China.
Tiana E CruzDepartment of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Richard A E EddenF.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Peter B BarkerF.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Peter C M van ZijlF.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Kennedy Krieger Institute · USJohns Hopkins University · US

Funding

TR&D 4: Algorithms for functional and anatomical brain analysisP41EB015909 · NIBIB · HUGO W. MOSER RES INST KENNEDY KRIEGER · PI MORI, SUSUMU · 2012 to 2020
$13.1M
Glutamate, hyperarousal and restless legs syndromeR01NS075184 · NINDS · JOHNS HOPKINS UNIVERSITY · PI ALLEN, RICHARD PUTNAM · 2012 to 2014
$1.2M
NIBIB NIH HHS P41 EB015909NINDS NIH HHS R01 NS075184
6 · The paper itself

Abstract

objectivesAltered brain iron homeostasis with regional iron deficiency has been previously reported in several studies of restless legs syndrome (RLS) patients. Inconsistencies still exist, however, in the reported iron changes in different brain regions and different RLS phenotypes. The purpose of this study was to assess differences in brain iron concentrations between RLS patients and healthy controls and their relation to severity of disease and periodic limb movement during sleep (PLMS).

methodsAssessment of brain iron was done using quantitative magnetic susceptibility measurement, which has been shown to correlate well with the tissue iron content in brain's gray matter. Thirty-nine RLS patients and 29 age-matched healthy controls were scanned at 7 T. Magnetic susceptibilities in substantia nigra (SN), thalamus, striatum, and several iron-rich gray matter regions were quantified and compared with related clinical measures.

resultsCompared with healthy controls, RLS patients showed significantly decreased magnetic susceptibility in the thalamus and dentate nucleus. No significant difference was found in the SN between RLS patients and healthy controls, but a significant correlation was observed between magnetic susceptibility in SN and the PLMS measure.

conclusionsUsing quantitative magnetic susceptibility as an in vivo indicator of brain iron content, the present study supports the general hypothesis of brain iron deficiency in RLS and indicates its possible link to PLMS.

Indexed as

Iron DeficienciesMagnetic Resonance ImagingFemaleHumansMaleMiddle AgedRestless Legs SyndromeSubstantia NigraThalamusBrain iron deficiencyPeriodic limb movement during sleepQuantitative susceptibility mappingRestless legs syndrome

Identifiers

PMID27544840
PMCPMC4992945
OpenAlexW2464850376

What OpenQuestion holds

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LicenceTDM
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.