AIM This study aimed to systematically map the severity of mirror movements in both hands in a prospective cohort of children with unilateral cerebral palsy, and to explore the relationship with hand function and brain lesion type.METHOD Seventy-eight children were included (41 males, 37 females; age 9y 4mo, SD 3y 1mo, range 5-15y). Mirror movements were scored during three repetitive tasks following Woods and Teuber criteria. Strength, tone, Melbourne Assessment, Jebsen-Taylor test, and Assisting Hand Assessment were evaluated. Lesions were classified into malformations (n=5), periventricular (n=43), cortico-subcortical (n=22), and postnatally acquired lesions (n=8).RESULTS Significantly more mirror movements were observed in the non-paretic versus the paretic hand (p≤0.003). Higher mirror movement scores in the non-paretic hand significantly correlated with lower distal strength and lower scores on unimanual and bimanual assessments (r=0.29-0.41). In the paretic hand, significant differences were found between lesion types (p=0.03). INTERPRETATIONThe occurrence of mirror movements in the non-paretic hand seems related to hand function while mirror movements in the paretic hand seem more related to the lesion timing, whereby children with earlier lesions present with more mirror movements.Children with unilateral cerebral palsy (CP) often experience difficulties in bimanual coordination which affects daily life activities. Apart from spasticity, muscle weakness, and sensory deficits the occurrence of mirror movements has also been suggested as a possible contributing factor that interferes with bimanual performance. 1 Mirror movements are described as 'involuntary movements of one body part that mirror the voluntary movement of the contralateral homologous body part'.2,3 They are mainly observed in the upper limbs, are symmetrical by nature, and their intensity increases with increasing task complexity or fatigue. 4,5 Physiological mirror movements are present in newborn infants, show a steep decrease between 5 years and 8 years of age, and disappear after 10 years of age. 4,6 These mirror movements are most likely to be caused by incomplete maturation of the corpus callosum and concurrent less effective interhemispheric inhibition. Unilateral tasks thereby invoke activation of bilateral motor cortices. [6][7][8] Further maturation of the transcallosal pathways with age ensures increasing inhibition of the motor cortex ipsilateral to the task hand, thus reducing the occurrence of mirror movements. 7Mirror movements have frequently been described in unilateral CP, 3,8,9 mostly in the non-paretic hand, albeit with large variability. 1,3,[8][9][10] The pathogenesis for their occurrence is not yet fully understood. One potential hypothesis could be the activation of bilateral primary motor cortices due to deficient interhemispheric inhibition caused by the underlying brain lesion. 2,6 Conversely, the persistence of ipsilateral corticospinal projections between the non-lesioned motor cortex and the paretic hand has ...

Introduction: Constraint-induced movement therapy (CIMT) improves upper limb (UL) motor execution in unilateral cerebral palsy (uCP). As these children also show motor planning deficits, action-observation training (AOT) might be of additional value. Here, we investigated the combined effect of AOT to CIMT and identified factors influencing treatment response. Methods: A total of 44 children with uCP (mean 9 years 6 months, SD 1 year 10 months) participated in a 9-day camp wearing a splint for 6 h/day and were allocated to the CIMT + AOT ( n = 22) and the CIMT + placebo group ( n = 22). The CIMT + AOT group received 15 h of AOT (i.e. video-observation) and executed the observed tasks, whilst the CIMT + AOT group watched videos free of biological motion and executed the same tasks. The primary outcome measure was bimanual performance. Secondary outcomes included measures of body function and activity level assessed before (T1), after the intervention (T2), and at 6 months follow-up (T3). Influencing factors included behavioural and neurological characteristics. Results: Although no between-groups differences were found ( p > 0.05; η2 = 0–16), the addition of AOT led to higher gains in children with initially poorer bimanual performance ( p = 0.02; η2 = 0.14). Both groups improved in all outcome measures after the intervention and retained the gains at follow up ( p < 0.01; η2 = 0.02–0.71). Poor sensory function resulted in larger improvements in the total group ( p = 0.03; η2 = 0.25) and high amounts of mirror movements tended to result in a better response to the additional AOT training ( p = 0.06; η2 = 0.18). Improvements were similar irrespective of the type of brain lesion or corticospinal tract wiring pattern. Conclusions: Adding AOT to CIMT, resulted in a better outcome for children with poor motor function and high amounts of mirror movements. CIMT with or without AOT seems to be more beneficial for children with poor sensory function. Trial registration: Registered at ClinicalTrials.gov on 22nd August 2017 (ClinicalTrials.gov identifier: NCT03256357).

Brain lesion characteristics (timing, location, and extent) and the type of corticospinal tract (CST) wiring have been proposed as determinants of upper limb (UL) motor function in unilateral cerebral palsy (uCP), yet an investigation of the relative combined impact of these factors on both motor and sensory functions is still lacking. Here, we first investigated whether structural brain lesion characteristics could predict the underlying CST wiring and we explored the role of CST wiring and brain lesion characteristics to predict UL motor and sensory functions in uCP. Fifty-two participants with uCP (mean age (SD): 11 y and 3 m (3 y and 10 m)) underwent a single-pulse Transcranial Magnetic Stimulation session to determine CST wiring between the motor cortex and the more affected hand (n = 17 contralateral, n = 19 ipsilateral, and n = 16 bilateral) and an MRI to determine lesion timing (n = 34 periventricular (PV) lesion, n = 18 corticosubcortical (CSC) lesion), location, and extent. Lesion location and extent were evaluated with a semiquantitative scale. A standardized protocol included UL motor (grip strength, unimanual capacity, and bimanual performance) and sensory measures. A combination of lesion locations (damage to the PLIC and frontal lobe) significantly contributed to differentiate between the CST wiring groups, reclassifying the participants in their original group with 57% of accuracy. Motor and sensory functions were influenced by each of the investigated neurological factors. However, multiple regression analyses showed that motor function was predicted by the CST wiring (more preserved in individuals with contralateral CST (p < 0.01)), lesion extent, and damage to the basal ganglia and thalamus. Sensory function was predicted by the combination of a large and later lesion and an ipsilateral or bilateral CST wiring, which led to increased sensory deficits (p < 0.05). These novel insights contribute to a better understanding of the underlying pathophysiology of UL function and may be useful to delineate individualized treatment strategies.

IntroductionThe clinical application of upper limb (UL) three-dimensional movement analysis (3DMA) in children with unilateral cerebral palsy (uCP) remains challenging, despite its benefits compared to conventional clinical scales. Moreover, knowledge on UL movement pathology and how this relates to clinical parameters remains scarce. Therefore, we investigated UL kinematics across different manual ability classification system (MACS) levels and explored the relation between clinical and kinematic parameters in children with uCP.Patients and methodsFifty children (MACS: I = 15, II = 26, III = 9) underwent an UL evaluation of sensorimotor impairments (grip force, muscle strength, muscle tone, two-point discrimination, stereognosis), bimanual performance (Assisting Hand Assessment, AHA), unimanual capacity (Melbourne Assessment 2, MA2) and UL-3DMA during hand-to-head, hand-to-mouth and reach-to-grasp tasks. Global parameters (Arm Profile Score (APS), duration, (timing of) maximum velocity, trajectory straightness) and joint specific parameters (angles at task endpoint, ROM and Arm Variable Scores (AVS)) were extracted. The APS and AVS refer respectively to the total amount of movement pathology and movement deviations of wrist, elbow, shoulder, scapula and trunk.ResultsLonger movement durations and increased APS were found with higher MACS-levels (p<0.001). Increased APS was also associated with more severe sensorimotor impairments (r = -0.30-(-0.73)) and with lower AHA and MA2-scores (r = -0.50-(-0.86)). For the joint specific parameters, stronger movement deviations distally were significantly associated with increased muscle weakness (r = -0.32-(-0.74)) and muscle tone (r = 0.33-(-0.61)); proximal movement deviations correlated only with muscle weakness (r = -0.35–0.59). Regression analysis exposed grip force as the most important predictor for the variability in APS (p<0.002).ConclusionWe found increased movement pathology with increasing MACS-levels and demonstrated the adverse impact of especially muscle weakness. The lower correlations suggest that 3DMA provides additional information regarding UL motor function, particularly for the proximal joints. Integrating both methods seems clinically meaningful to obtain a comprehensive representation of all aspects of a child’s UL functioning.

Knowledge on long-term evolution of upper limb function in children with unilateral cerebral palsy (CP) is scarce. The objective was to report the five-year evolution in upper limb function and identify factors influencing time trends. Eighty-one children (mean age 9 y and 11 mo, SD 3 y and 3 mo) were assessed at baseline with follow-up after 6 months, 1, and 5 years. Passive range of motion (PROM), tone, muscle, and grip strength were assessed. Activity measurements included Melbourne Assessment, Jebsen-Taylor test, Assisting Hand Assessment (AHA), and ABILHAND-Kids. At 5-year follow-up, PROM (p < 0.001) and AHA scores (p < 0.001) decreased, whereas an improvement was seen for grip strength (p < 0.001), Melbourne Assessment (p = 0.003), Jebsen-Taylor test (p < 0.001), and ABILHAND-Kids (p < 0.001). Age influenced the evolution of AHA scores (p = 0.003), with younger children being stable over time, but from 9 years onward, children experienced a decrease in bimanual performance. Manual Ability Classification System (MACS) levels also affected the evolution of AHA scores (p = 0.02), with stable scores in MACS I and deterioration in MACS II and III. In conclusion, over 5 years, children with unilateral CP develop more limitations in PROM, and although capacity measures improve, the spontaneous use of the impaired limb in bimanual tasks becomes less effective after the age of 9 years.