عدم تقارن ساختاری در قشر حرکتی در سندرم آسپرگر
Abstract
Introduction
Materials and methods
Participants and study design
Magnetic resonance imaging (MRI)
Navigated transcranial magnetic stimulation (nTMS)
Analysis of TMS
Analysis of MRI
Assessment of handedness, head circumference, manual dexterity and physical activity
Statistical analysis
Results
nTMS
MRI
Discussion
Strengths and limitations of the study
Compliance with ethical standards
References
Abstract
Motor functions are frequently impaired in Asperger syndrome (AS). In this study, we examined the motor cortex structure and function using navigated transcranial magnetic stimulation (nTMS) and voxel-based morphometry (VBM) and correlated the results with the box and block test (BBT) of manual dexterity and physical activity in eight boys with AS, aged 8–11 years, and their matched controls. With nTMS, we found less focused cortical representation areas of distinct hand muscles in AS. There was hemispheric asymmetry in the motor maps, silent period duration and active MEP latency in the AS group, but not in controls. Exploratory VBM analysis revealed less gray matter in the left postcentral gyrus, especially in the face area, and less white matter in the precentral area in AS as compared to controls. On the contrary, in the right leg area, subjects with AS displayed an increased density of gray matter. The structural findings of the left hemisphere correlated negatively with BBT score in controls, whereas the structure of the right hemisphere in the AS group correlated positively with motor function as assessed by BBT. These preliminary functional (neurophysiological and behavioral) findings are indicative of asymmetry, and co-existing structural alterations may reflect the motor impairments causing the deteriorations in manual dexterity and other motor functions commonly encountered in children with AS.
Results
Both the imaging and nTMS session were well-tolerated. No abnormalities related to motor areas were found in the MRIs. The demographic and clinical characteristics of the AS and control group are shown in Table 1. Although our original aim was to recruit only right-handed subjects, there was one left-handed and one ambidextrous (predominantly lefthanded) boy in the AS group. The AS boys received lower scores in the BBT (right hand p=0.028, left hand p=0.003). The AS boys also performed more poorly with their left hand than with their right hand (p=0.021), whereas no such difference was observed in the control group (p=0.799). No mirror movements were observed during the BBT. The head circumference was smaller (p=0.038) and habitual physical activity level was lower in AS subjects than in controls (p=0.028). (Table 1).