THE NORMAL BRAIN-STEM FROM INFANCY TO OLD-AGE - A MORPHOMETRIC MRI STUDY

Our purpose was to develop a method of measuring the size of the brain stem by routine MRI and to determine brain stem dimensions in a norma l population. We examined 174 subjects, aged 4 months to 86 years, wit h no known brain disease. Sagittal midline diameters of the mesencepha lon, pens and medulla oblongata were measured on sagittal T1-weighted images, coronal diameters from axial T2-weighted images. The adult mid sagittal diameter of the mesencephalon was reached at the age of 6 yea rs, and decreased slightly after 45-50 years. Pontine dimensions incre ased until the age of 20 years and did not subsequently decrease. The midsagittal and midcoronal diameters of the medulla oblongata stopped increasing at the ages of 6 and 8 years, respectively. Minimal reducti on in the midsagittal diameter occurs after 50 years. Normal ranges fo r each dimension were recorded. Knowledge of the normal variation in s ize of the brain stem can be helpful in the investigation of neurodege nerative diseases. The method described is rapid and needs no addition al hard-or software. An additonal finding was an increase in large ver mian sulci in subjects over 50 years of age.