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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Clinical correlates of white-matter abnormalities on head magnetic resonance imaging
N Lasbury1, B Garg, M Edwards-Brown
1Department of Neurology, Indiana University School of Medicine, Riley Children's Hospital, Indianapolis, USA.
Insights
White-matter abnormalities in young children correlate with muscle tone issues. Decreased white matter quantity was seen in all groups, with specific patterns linked to tone and reflexes.
Area of Science:
- Neuroscience
- Pediatric Neurology
- Radiology
Background:
- White-matter abnormalities on brain MRI are associated with neurological deficits.
- Understanding the relationship between white matter structure and muscle tone is crucial for early diagnosis and intervention in children.
Purpose of the Study:
- To investigate the correlation between white-matter abnormalities detected via brain MRI and clinical assessments of muscle tone and reflexes in children under five.
- To quantify cerebral white matter using MRI-derived ratios and corpus callosum thickness.
Main Methods:
- Retrospective review of cranial MRI scans in children under five with white-matter abnormalities.
- Measurement of white matter quantity using two ratios (R1, R2) and corpus callosum thickness.
- Evaluation of white matter signal intensity using fluid-attenuated inversion-recovery (FLAIR) images (0-4+ grading).
- Comparison with a control group of children with normal MRI and tone.
Main Results:
- Children with white-matter abnormalities showed significantly reduced white matter quantity compared to controls.
- Decreased muscle tone was associated with less severe white matter signal abnormalities.
- Increased muscle tone correlated with a higher frequency of increased reflexes and more pronounced signal abnormalities.
- Normal muscle tone in the context of white-matter abnormalities indicated the least degree of cerebral white matter deficiency.
Conclusions:
- White matter quantity and signal intensity on MRI are linked to muscle tone and reflexes in young children.
- Hypotonia with normal reflexes may be associated with reduced white matter quantity and normal signal intensity.
- Spasticity may be linked to reduced white matter quantity with increased signal intensity, suggesting potential for conditions like cerebral palsy.
Abstract:
We undertook this study to investigate the relationship between white-matter abnormalities (seen on brain magnetic resonance imaging [MRI]) and muscle tone and muscle stretch reflexes on clinical examination. We identified all patients less than 5 years of age who had undergone cranial MRI studies at Riley Hospital for Children between June 30, 1999, and July 1, 2000, whose scans were read as showing white-matter abnormalities. We measured two ratios and the thickness of the corpus callosum as indicators of the quantity of cerebral white matter. The ratios were R1, the ratio of the thickness of the white matter at the level just above the body of the lateral ventricle compared with the width of the hemisphere, and R2, the ratio of the thickness of the white matter to the width of the hemisphere at the level of the trigone of the lateral ventricle. The thickness of the corpus callosum was measured at the junction of the anterior two thirds and the posterior third. We also evaluated the signal intensity of the cerebral white matter by reviewing the fluid-attenuated inversion-recovery images and grading the signal as normal to severely abnormal depending on the degree and extent of high signal intensity seen (0 = normal to 4+). Thirty-eight children less than 5 years of age who underwent MRI scans between June and August 2000 and who were found to have normal tone prospectively and normal MRI scan on review served as a control group. We identified 215 patients who had white-matter abnormalities; of these, only 142 (66%) had documented tone assessments in their medical record. Our study group was divided into three groups: increased (n = 35), decreased (n = 53), and normal tone (n = 54). All three measurements of white matter in each of the three study groups were significantly below values for control children. The children with white-matter abnormalities and decreased tone had significantly less signal intensity abnormality than the other study groups. Children with white-matter abnormalities and increased tone had a greater frequency of increased reflexes and tended to have more signal abnormalities than the other groups. The group of children with white-matter abnormalities and normal tone had the least amount of cerebral white-matter deficiency of the three study groups. In patients with strikingly decreased quantities of cerebral white matter, those with normal signal-intensity white matter are likely to be hypotonic with normal reflexes and those with increased signal intensity in the white matter are likely to be spastic.
