Neuroanatomical correlates of gross manual dexterity in children with unilateral spastic cerebral palsy

Abstract

Unilateral spastic Cerebral Palsy (UCP) results from congenital brain injury, and Magnetic Resonance Imaging (MRI) has a role in understanding the etiology and severity of brain insult. In UCP, functional impairment predominantly occurs in the upper limb (UL) of the more affected side, where manual ability and dexterity are typically reduced. Also, mirror movements (MMs), are often present in UCP, with a further possible negative functional impact. This study aims to investigate the relationships among neuroanatomical characteristics of brain injury at MRI, manual functional impairment and MMs, in children with UCP. Thirty-five children with UCP participated in the study (20, M = 15, F, mean age 9.2 ± 3.5 years). Brain lesions at MRI were categorized according to the Magnetic Resonance Classification System (MRICS) and by using a semi-quantitative MRI (sqMRI) scale. Gross manual performance was assessed through Manual Ability Classification System (MACS) and the Box and Block Test (BBT), and MMs by Woods and Teuber scale, for both hands. Non-parametric correlation analyses were run to determine the relationship between neuroanatomical and functional features. Regression models were run to explore the contribution of neuroanatomical features and MMs to UL function. Correlation analyses revealed moderate to strong associations between sqMRI scores contralateral to the more affected side and UL functional impairment on MACS and BBT, with more severe brain injuries significantly correlating with poorer function in the more affected hand. No association emerged between brain lesion severity scores and MMs. MRICS showed no association with MACS or BBT, while a significant correlation emerged between MRICS category and MMs in the more affected hand, with brain lesion category that are suggestive of presumed earlier injury being associated with more severe MMs. Finally, exploratory regression analyses showed that neuroanatomical characteristics of brain injury and MMs contributed to the variability of UL functional impairment. This study contributes to the understanding of the neuroanatomical and neurological correlates of some aspects of manual functional impairment in UCP by using a simple clinical brain MRI assessment.

Keywords: Magnetic Resonance Imaging; children; gross manual dexterity; mirror movements; neuroanatomical correlates; unilateral cerebral palsy.

Figure 1

Magnetic Resonance Imaging axial FLuid-Attenuated Inversion Recovery (FLAIR) representative images of some different brain lesion type and severity are provided, with corresponding scores for manual functional impairment and Mirror Movements (MMs). (A) Perinatal stroke in the left middle cerebral artery territory (main branch). MRICS type C, predominant gray matter injury. Brain lesion severity score sqMRI GS: 20.5. More affected hand BBT, 13; MMs, 2. Less affected hand BBT, 48; MMs, 7. (B) Perinatal stroke in the left MCA territory (cortical branch). MRICS type C, predominant gray matter injury. Brain lesion severity score sqMRI GS, 13.5. More affected hand BBT, 48; MMs, 4. Less affected hand BBT, 13; MMs, 1 (C) Right periventricular venous infarction. MRICS B, predominant white matter injury. Brain lesion severity score sqMRI GS, 4. More affected hand BBT, 34; MMs, 2. Less affected hand BBT, 47; MMs, 2. GS, global Score; MRICS, Magnetic Resonance Imaging Classification System; BBT, Box and Block Test; MACS, Manual Ability Classification System; MMs, Mirror Movements.