Upper Limb Function and Cortical Organization in Youth with Unilateral Cerebral Palsy

Abstract

Aim: To explore the relationship between motor cortical and descending motor pathway reorganization, lesion type, and upper limb function in youth with unilateral cerebral palsy (CP).Methods: Twenty participants with unilateral CP (mean age 15 ± 3 years; 11 males) completed a range of upper limb functional measures. Structural MRI, diffusion-weighted, and functional MRI were conducted to determine type and extent of brain lesion, descending white matter integrity, and whole-brain activity during affected hand use. Single pulse transcranial magnetic stimulation (TMS) (n = 12) was used to examine functional integrity of the corticospinal pathway as well as primary motor cortex intracortical and interhemispheric inhibition from motor-evoked potentials and silent periods.Results: Fractional anisotropy measures within the posterior limb of the internal capsule were a predictor of upper limb function (R2 = 0.41, F = 11.3, p = 0.004). Participants with periventricular lesions tended to have better upper limb function [F(2, 17) = 42.48, p < 0.0001]. Five participants with evidence of cortical reorganization and functional ipsilateral projections to their affected hand had worse upper limb function. Deficits in intracortical and interhemispheric inhibitory mechanisms were found in participants with worse upper limb function (Melbourne Assessment of Unilateral Upper Limb Function: Mann Whitney p = 0.02).Conclusion: Neuroimaging and TMS can provide useful information related to hand function of individuals with unilateral CP and may have potential to assist as a predictive tool and/or guide rehabilitation.

How does the interaction of presumed timing, location and extent of the underlying brain lesion relate to upper limb function in children with unilateral cerebral palsy?

“…Bilateral brain damage in children with unilateral CP has been previously reported although frequencies were highly variable. 6-8, 10 Correlations between the contralesional global scores and AHA performance were not significant for both groups. This is in line with Holmefur et al, 9 who already reported the lack of impact of bilateral abnormalities on UL function.…”

Intensive upper limb intervention with self-management training is feasible and promising for older children and adolescents with unilateral cerebral palsy

“…These characteristics could possibly have influenced their response to treatment. In future studies, with the availability of brain imaging techniques (Krageloh-Mann & Horber, 2007;Scheck, Boyd, & Rose, 2012) and knowledge of the relationship between specific brain lesions, corticomotor projection patterns, and hand function (Arnfield, Guzzetta, & Boyd, 2013;Feys et al, 2010;Holmstrom et al, 2010;Mackey, Stinear, Stott, & Byblow, 2014), UL interventions may be better tailored to the neurological characteristics of individual patients.…”

Measuring motor-training induced neuroplasticity using diffusion and functional MRI: a sensitive, pathology-robust approach

“…Distinct changes in activation patterns have been reported in rehabilitative studies of adult stroke (postrehabilitation versus retention), 111 hemispherectomy (pre-versus postrehabilitation), 125 and paediatric CP (preversus postrehabilitation), 66 despite subjects demonstrating stable motor scores. In unilateral CP, the degree of S1M1 activation for active and passive movements may not correlate with motor scores, 105,113 and results for sensory impairment are mixed. 57,105,126 Similarly, for stroke, activation of the ipsilateral primary motor cortex has been associated with both good and poor behavioural outcomes.…”

“…112 Both stroke and unilateral CP patients, however, regularly demonstrate robustly bilateral activation. 105,113,114 These balances of activation are typically calculated as laterality index (LI):…”