The relationship between neuroimaging and motor outcome in children with cerebral palsy: A systematic review-Part B diffusion imaging and tractography

Background: Diffusion magnetic resonance imaging (dMRI) is able to detect, localize and quantify subtle brain white matter abnormalities that may not be visible on conventional structural MRI. Over the past years, a growing number of studies have applied dMRI to investigate structure-function relationships in children with cerebral palsy (CP).

Aims: To provide an overview of the recent literature on dMRI and motor function in children with CP.

Methods: A systematic literature search was conducted in PubMed, Embase, Cochrane Central Register of Controlled trials, Cinahl and Web of Science from 2012 onwards.

Results: In total, 577 children with CP in 19 studies were included. Sixteen studies only included unilateral CP, while none included dyskinetic CP. Most studies focused on specific regions/tracts of interest (n = 17) versus two studies that investigated the whole brain. In unilateral and bilateral CP, white matter abnormalities were widespread including non-motor areas. In unilateral CP, consistent relationships were found between white matter integrity of the corticospinal tract and somatosensory pathways (e.g. thalamocortical projections, medial lemniscus) with upper limb sensorimotor function. The role of commissural and associative tracts remains poorly investigated. Also results describing structure-function relationships in bilateral CP are scarce (n = 3).

Conclusions: This review underlines the importance of both the motor and somatosensory tracts for upper limb sensorimotor function in unilateral CP. However, the exact contribution of each tract requires further exploration. In addition, research on the relevance of non-motor pathways is warranted, as well as studies including other types of CP.