Morphologic Variants of the Hand Motor Cortex in Developing Brains from Neonates through Childhood Assessed by MR Imaging

Abstract

BACKGROUND AND PURPOSE: Knowledge of anatomic markers of the hand motor cortex is essential in the evaluation and treatment of motor neurologic diseases for both adults and developing populations. However, hand motor cortex variants in developing brains remain to be investigated. Our objective was to observe morphologic variants of the hand motor cortex in developing brains from neonates through childhood. MATERIALS AND METHODS:In this study, 542 participants (0$15 years of age) were retrospectively enrolled and divided into different age groups. The hand motor cortex morphology was evaluated on the basis of 3D T1WI. Variations in hand motor cortex variants were compared among different age groups. Inter-gender and interhemispheric differences of hand motor cortex variants were also evaluated. RESULTS:Various hand motor cortex variants could be observed in developing brains, even in the neonatal period. One new morphologic shape, "immature X," was found in neonates and infants. The proportion of this new shape decreased dramatically during the first year after birth, then disappeared after 1 year of age. It persisted for a longer time in the right hemisphere and in males. However, sex or hemispheric effects on the distribution of the proportion of variants were not statistically significant. Furthermore, the proportion of concordance of the bilateral hand motor cortex showed an increasing trend with age (P ¼ .006), higher in females than males.CONCLUSIONS: Various hand motor cortex variants already existed at birth. The distribution of proportions of different variants developmentally varied during the first year after birth and became stable after 1 year of age. The concordance of the bilateral hand motor cortex could be influenced by age and sex.

A Narrative Review of Stroke of Cortical Hand Knob Area

“…Six variations of anatomical appearance, including epsilon, mediately asymmetric epsilon, laterally asymmetric epsilon, null, mature omega, and immature omega, have been reported in the literature (Figure 2). These variations describe adult brain imaging findings, and when developing brains are considered, immature omega variants are often reported [28].…”

“…Six variations of anatomical appearance, including epsilon, mediately asymmetric epsilon, laterally asymmetric epsilon, null, mature omega, and immature omega, have been reported in the literature (Figure 2). These variations describe adult brain imaging findings, and when developing brains are considered, immature omega variants are often reported [28]. The hand knob area of the premotor cortex has been studied by Francis et al using microelectrode recordings, and it was found that face, arm, leg, and head movements are intermixed in the hand knob area.…”

Volume development changes in the occipital lobe gyrus assessed by MRI in foetuses with isolated ventriculomegaly correlate with neurological development in infancy and early childhood

“…It is hypothesized that prenatal enlargement of the occipital cortex may have some in uence on postnatal language development. Fine motor development is closely related to the development of various regions of the brain; it is a fundamental component of hand [30] and visuomotor function and visual-motor integration, which has been shown to be a facilitator of visuomotor function, although the causal relationship of this mediation is unclear [31] . Fine motor skills were associated with future writing skills, reading and writing.…”

Development and validation of a novel model based on hand knob score and white matter injury on MRI to predict hand function in children with cerebral palsy

“…Neuroimaging studies have confirmed that hand dysfunction often involves multiple circuits of motor function (5)(6)(7). The hand motor area is mainly restricted to a specific part of the precentral gyrus called the hand knob, and lesions in this area are associated with hand dysfunction (8)(9)(10).…”