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Author Notes:

Correspondence: brynm@uidaho.edu

Braden J. Lawrence and Aintzane Urbizu contributed equally to this manuscript.

AU, AB, BAM, BJI, BGR, CM, FL, JNO, JRK, MGL, PAA, and RST conceived and designed the study, obtained and processed the MRI data.

AU, BJI, BAM, CM, MGL, and JNO were involved in patient selection and clinical data acquisition.

AU, BAM, BJL, and JAC were involved in design and implementation of the statistical portion of the paper as well as interpretation of the data and writing the manuscript.

All authors contributed to editing of the manuscript.

All authors read and approved the final manuscript.

The authors declare that they have no competing interests.


Research Funding:

Publication of this article was funded by the University of Idaho Open Access Publishing Fund.

This work was supported by The Chiari and Syringomyelia Patient Education Foundation and NIH NINDS grant 1R15NS071455-01 (FL), NIH NIGMS grants P20GM103408 (BAM) and 4U54GM104944-04 (BAM) and the University of Washington School of Medicine Medical Student Research Training Program (MSRTP–BJL).

AU was the recipient of a Postdoctoral Fellowship from Fundación Ramón Areces (Spain) and mentored by BAM.

BAM served as Director of the Conquer Chiari Research Center and received research funding from American Syringomyelia and Chiari Alliance Project at the time of this study.

FL served as Executive Director at Conquer Chiari Research Center and received research funding from Conquer Chiari at the time of this study.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Neurosciences & Neurology
  • Cerebellar tonsil
  • Inter-operator reliability
  • Morphometric
  • MRI
  • Syringomyelia
  • Type 1 Chiari malformation
  • FLOW

Cerebellar tonsil ectopia measurement in type I Chiari malformation patients show poor inter-operator reliability

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Journal Title:

Fluids and Barriers of the CNS


Volume 15, Number 1


, Pages 33-33

Type of Work:

Article | Final Publisher PDF


Background: Type 1 Chiari malformation (CM-I) has been historically defined by cerebellar tonsillar position (TP) greater than 3-5 mm below the foramen magnum (FM). Often, the radiographic findings are highly variable, which may influence the clinical course and patient outcome. In this study, we evaluate the inter-operator reliability (reproducibility) of MRI-based measurement of TP in CM-I patients and healthy controls. Methods: Thirty-three T2-weighted MRI sets were obtained for 23 CM-I patients (11 symptomatic and 12 asymptomatic) and 10 healthy controls. TP inferior to the FM was measured in the mid-sagittal plane by seven expert operators with reference to McRae's line. Overall agreement between the operators was quantified by intraclass correlation coefficient (ICC). Results: The mean and standard deviation of cerebellar TP measurements for asymptomatic (CM-Ia) and symptomatic (CM-Is) patients in mid-sagittal plane was 6.38 ± 2.19 and 9.57 ± 2.63 mm, respectively. TP measurements for healthy controls was 0.48 ± 2.88 mm. The average range of TP measurements for all data sets analyzed was 7.7 mm. Overall operator agreement for TP measurements was relatively high with an ICC of 0.83. Conclusion: The results demonstrated a large average range (7.7 mm) of measurements among the seven expert operators and support that, if economically feasible, two radiologists should make independent measurements before radiologic diagnosis of CM-I and surgery is contemplated. In the future, an objective diagnostic parameter for CM-I that utilizes automated algorithms and results in smaller inter-operator variation may improve patient selection.

Copyright information:

© 2018 The Author(s).

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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