The evaluation of Wallerian degeneration in chronic paediatric middle cerebral artery infarction using diffusion tensor MR imaging.
BACKGROUND
The long-term neuromotor outcome in paediatric strokes ranges from normal to varying degrees of hemiplegia. We evaluated the indices of diffusion tensor magnetic resonance imaging (DTI), fractional anisotropy and mean diffusivity to determine if these indices can identify and quantify the presence of Wallerian degeneration in paediatric patients with chronic middle cerebral artery infarction, and to determine if these quantitative parameters correlate with the neuromotor outcome.


METHODS
Eleven children (mean age 8.1 years) with evidence of unilateral middle cerebral artery stroke on magnetic resonance imaging and 10 control subjects (mean age 8.7 years) were studied. Neuromotor outcome was based on functions of the affected hand: mild (n = 3), moderate (n = 6), and severe (n = 2) hemiparesis. Fractional anisotropy and mean diffusivity of the ipsilateral corticospinal tract were compared with matched contralateral regions using the Mann-Whitney U test. Spearman's test was performed to study the relationship between neuromotor outcome and the following: ipsilateral-to-contralateral ratio of fractional anisotropy, mean diffusivity and cerebral peduncle area, and the largest infarction size.


RESULTS
For control subjects, there were no significant differences in fractional anisotropy and mean diffusivity of the corticospinal tract between the right and left side. For patients, fractional anisotropy decreased by 18% and mean diffusivity increased by 8% in the ipsilateral compared to the contralateral corticospinal tract. Neuromotor outcome correlated with the ipsilateral-to-contralateral ratio of fractional anisotropy (r = -0.638, p = 0.035) but not with the mean diffusivity ratio, cerebral peduncle area ratio and largest infarction size.


CONCLUSIONS
DTI can be used to detect and quantify Wallerian degeneration in chronic paediatric middle cerebral artery infarction. Our preliminary data show that loss of anisotropy in the corticospinal tract correlates with neuromotor outcome.
Department of Diagnostic Radiology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China. plkhong@hkucc.hku.hk
Pek-Lan
PL
Khong
Lin-Jiang
LJ
Zhou
Gaik-Cheng
GC
Ooi
Brian H Y
BH
Chung
Raymond T F
RT
Cheung
Virginia C N
VC
Wong
D000293:Adolescent; D016880:Anisotropy; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006225:Hand / Q000503:physiopathology; D006801:Humans; D007223:Infant; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D020772:Internal Capsule / Q000473:pathology; D008297:Male; D008636:Mesencephalon / Q000473:pathology; D009068:Movement; D009420:Nervous System / Q000503:physiopathology; D010291:Paresis / Q000209:etiology / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000473:pathology; D014855:Wallerian Degeneration / Q000175:diagnosis* / Q000209:etiology*