Craniometric measures of microcephaly using MRI.
Academic Article
Overview
abstract
BACKGROUND: Microcephalic brains exhibit varying sizes, shapes, and dimensions when compared to normocephalic counterparts, but the extent of these differences is unresolved. AIMS: To ascertain developmental changes in brain morphology using craniometric (linear brain) measures derived from MRI in microcephalic individuals and in normocephalic controls. STUDY DESIGN: A retrospective, cross-sectional cohort study. SUBJECTS: Twenty-one primary and secondary microcephalic individuals ages 2 postnatal weeks to 8.5 years with occipito-frontal circumference<2nd percentile for age; 83 age-equivalent normocephalic controls. OUTCOME MEASURES: Age, sex, weight, height, body mass index, occipito-frontal circumference, and diagnosis prompting the MRI scan. Sixteen craniometric measures to determine specific ratios and age-related changes in brain shape and size. RESULTS: Microcephalic infants and children not only have abnormally small brains but also proportionately lower weights and heights. The brain volumes of both primary and secondary microcephalics were quite variable, ranging from 266 to 723 cm(3) and 440 to 730 cm(3), respectively (p=0.34). Despite their smaller sizes, the shapes of 15/21 (71%) microcephalic brains were similar to those of age-equivalent controls. Cerebral hemispheric configurations were not consistent among the 6 misshapen brains, which included 2 primary, 3 secondary, and 1 unknown microcephalics. Older microcephalic brains could be distinguished from their normocephalic counterparts by two specific craniometric ratios (frontal cerebellar pole/sagittal cerebral length; axial temporal width/axial cerebellar width), each incorporating cerebral and cerebellar dimensions in either length or width. CONCLUSIONS: The findings should provide useful information for distinguishing the characteristics of both modern and ancient microcephalic from normocephalic brains.
