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Abstract
Objective To compare the clinical utility of volume-based ratios with the standard linear ratio of Evans index (EI) by examining their associations with gait, cognition, and other patient and imaging variables.
Methods From MRI scans of 1,774 participants in the Mayo Clinic Study of Aging, we calculated 3 ventricle size measures: Evan index (frontal horn width divided by widest width of skull inner table), total ventricular volume, and frontal horn volume as ratios of total intracranial volume. Gait was measured by a timed 25-foot walk and cognition by a composite of psychometric tests. We also evaluated variables associated with the measures of ventricular size. Further, we evaluated gait and cognition associations with MRI of extraventricular findings seen in normal-pressure hydrocephalus: disproportionate enlargement of subarachnoid space (DESH) and focal sulcal dilations (FSD).
Results Ventricular volume measures had stronger association with gait and cognition measures than EI. In decreasing order of strength of association with ventricle size were DESH, FSD, white matter hyperintensity volume ratio, age, male sex, cortical thickness, and education. Modest evidence was observed that FSD was associated with future decline in gait and cognition.
Conclusion Ventricular volume measures are clinically more useful than EI in indicating current and future gait and cognition. Multiple factors are associated with ventricle volume size, including FSD and DESH, suggesting that changes in CSF dynamics may go beyond simple ventriculomegaly.
Glossary
- CI=
- confidence interval;
- DESH=
- disproportionately enlarged subarachnoid hydrocephalus;
- EI=
- Evans index;
- FH=
- frontal horn;
- FHVR=
- ratio of frontal horn volume to total intracranial volume;
- FSD=
- focal sulcal dilation;
- MCALT=
- Mayo Clinic Adult Lifespan Template;
- MCSA=
- Mayo Clinic Study of Aging;
- NPH=
- normal-pressure hydrocephalus;
- TV=
- total ventricular;
- TVVR=
- ratio of total ventricular volume to total intracranial volume;
- WMHV=
- white matter hyperintensity volume;
- WMHVR=
- white matter hyperintensity volume as a ratio of white matter volume
Footnotes
Abstract presented at the 10th Meeting of the International Society for Hydrocephalus and Cerebrospinal Fluid Disorders, Bologna, Italy, October 19–22, 2018.
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received December 28, 2018.
- Accepted in final form July 31, 2019.
- © 2019 American Academy of Neurology
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