A transcranial magnetic stimulation study for the investigation of corticospinal motor pathways in children with cerebral palsy

Effects of repetitive transcranial magnetic stimulation on motor function and language ability in cerebral palsy: A systematic review and meta-analysis

OBJECTIVE

This review was conducted to assess the quality of the evidence of effectiveness of repetitive transcranial magnetic stimulation (rTMS) in treating motor and language ability of cerebral palsy (CP).

METHOD

Medline, Cochrane library, Web of Science, Embase, PubMed, and CNKI databases were searched up to July 2021 by two independent reviewers. Randomized controlled trials (RCTs) that were published in English and Chinese and met the following criteria were included. The population comprised patients who met the diagnostic criteria for CP. Intervention included the following: comparison about rTMS and sham rTMS or comparison about rTMS combine with other physical therapy and other physical therapy. Outcomes included motor function, as follows: gross motor function measure (GMFM), Gesell Development Diagnosis Scale, fine motor function measure (FMFM), Peabody developmental motor scale, and Modified Ashworth scale. For language ability, sign-significant relation (S-S) was included. Methodological quality was assessed using the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Finally, 29 studies were included in the meta-analysis. Results of evaluation using the Cochrane Collaborative Network Bias Risk Assessment Scale showed that 19 studies specifically explained randomization, among which two studies described allocation concealment, four studies blinded participants and persons and had low risk of bias, and six studies explained that the assessment of outcome measures was blinded. Significant improvements in motor function were observed. The GMFM of total score was determined by using the random-effect model [I2= 88%; MD = -1.03; 95% CI (-1.35, -0.71); P < 0.0001] and FMFM was determined by using the fixed-effect model [P = 0.40 and I2 = 3%; SMDs = -0.48, 95% CI (-0.65, -0.30); P < 0.01]. For language ability, the language improvement rate was determined using a fixed-effect model [P = 0.88 and I2 = 0%; MD = 0.37, 95% CI (0.23, 0.57); P < 0.01]. According to the PEDro scale, 10 studies had low-quality, four studies had excellent quality, and the other studies had good quality. Using the GRADEpro GDT online tool, we included a total of 31 outcome indicators, as follows: 22 for low quality, seven for moderate quality, and two for very low quality.

CONCLUSION

The rTMS could improve the motor function and language ability of patients with CP. However, rTMS prescriptions varied, and the studies had low sample sizes. Studies using rigorous and standard research designs about prescriptions and large samples are needed to collect sufficient evidence about the effectiveness of using rTMS to treat patients with CP.

Brain functional reorganization in children with hemiplegic cerebral palsy: Assessment with TMS and therapeutic perspectives

Transcranial magnetic stimulation (TMS) can be a useful tool for the assessment of the brain functional reorganization in subjects with hemiplegic cerebral palsy (HCP). In this review, we performed a systematic search of all studies using TMS in order to explore the neuroplastic changes that occur in HCP patients. We aimed at investigating the usefulness of TMS to explore cortical excitability, plasticity and connectivity changes in HCP. Children with HCP due to unilateral lesions of the corticospinal system had ipsilateral motor evoked potentials (MEPs) similar to those recorded contralaterally. TMS studies demonstrated that occupational and constraint-induced movement therapy were associated with significant improvements in contralateral and ipsilateral corticomotor projection patterns. In addition, after intensive bimanual therapy, children with HCP showed increased activation and size of the motor areas controlling the affected hand. A TMS mapping study revealed a mediolateral location of the upper and lower extremity map motor cortical representations. Deficits in intracortical and interhemispheric inhibitory mechanisms were observed in HCP. Early hand function impairment correlated with the extension of brain damage, number of involved areas, and radiological signs of corticospinal tract (CST) degeneration. Clinical mirror movements (MMs) correlated with disability and CST organization in subjects with HCP and a positive relationship was found between MMs and MEPs strength. Therefore, TMS studies have shed light on important pathophysiological aspects of motor cortex and CST reorganization in HCP patients. Furthermore, repetitive TMS (rTMS) might have therapeutic effects on CST activities, functional connectivity and clinical status in children with HCP.

Bilateral Motor Responses to Transcranial Magnetic Stimulation in Preterm Children at 9 Years of Age

OBJECTIVE

This study was aimed to evaluate motor tracts integrity in nondisabled preterm-born (PT) children at 9 years of age.

METHODS

Overall, 18 PT and 13 term-born (T) children without motor disability were assessed by transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were measured bilaterally from the abductor pollicis brevis (APB) and the tibialis anterior (TA) muscles. Muscle responses could be stimulated from all patients.

RESULTS

Overall, 83.3 and 23.1% of PT and T children, respectively, had mild clumsiness (p = 0.001). One PT and three T children had immediate bilateral responses in the upper extremities. Seven PT children had delayed ipsilateral APB responses after left and ten after right TMS. Three controls had delayed ipsilateral responses. Ipsilateral lower extremity responses were seen in one PT after right and two PT children and one T child after left TMS. The results did not correlate to groups, genders, clumsiness, or handedness.

CONCLUSION

Children of PT and T may have bilateral motor responses after TMS at 9 years of age. Ipsilateral conduction emerges immediately or more often slightly delayed and more frequently in upper than in lower extremities.

SIGNIFICANCE

Bilateral motor conduction reflects developmental and neurophysiological variability in children at 9 years of age. MEPs can be used as a measure of corticospinal tract integrity in PT children.

Changes of Structural Brain Network Following Repetitive Transcranial Magnetic Stimulation in Children With Bilateral Spastic Cerebral Palsy: A Diffusion Tensor Imaging Study

Introduction: Bilateral spastic cerebral palsy (BSCP) is the most common subtype of cerebral palsy (CP), which is characterized by various motor and cognitive impairments, as well as emotional instability. However, the neural basis of these problems and how repetitive transcranial magnetic stimulation (rTMS) can make potential impacts on the disrupted structural brain network in BSCP remain unclear. This study was aimed to explore the topological characteristics of the structural brain network in BSCP following the treatment of rTMS. Methods: Fourteen children with BSCP underwent 4 weeks of TMS and 15 matched healthy children (HC) were enrolled. Diffusion tensor imaging (DTI) data were acquired from children with bilateral spastic cerebral palsy before treatment (CP1), children with bilateral spastic cerebral palsy following treatment (CP2) and HC. The graph theory analysis was applied to construct the structural brain network. Then nodal clustering coefficient (C _i ) and shortest path length (L _i ) were measured and compared among groups. Results: Brain regions with significant group differences in C _i were located in the left precental gyrus, middle frontal gyrus, calcarine fissure, cuneus, lingual gyrus, postcentral gyrus, inferior parietal gyri, angular gyrus, precuneus, paracentral lobule and the right inferior frontal gyrus (triangular part), insula, posterior cingulate gyrus, precuneus, paracentral lobule, pallidum. In addition, significant differences were detected in the L _i of the left precental gyrus, lingual gyrus, superior occipital gyrus, middle occipital gyrus, superior parietal gyrus, precuneus and the right median cingulate gyrus, posterior cingulate gyrus, hippocampus, putamen, thalamus. Post hoc t-test revealed that the CP2 group exhibited increased C _i in the right inferior frontal gyrus, pallidum and decreased L _i in the right putamen, thalamus when compared with the CP1 group. Conclusion: Significant differences of node-level metrics were found in various brain regions of BSCP, which indicated a disruption in structural brain connectivity in BSCP. The alterations of the structural brain network provided a basis for understanding of the pathophysiological mechanisms of motor and cognitive impairments in BSCP. Moreover, the right inferior frontal gyrus, putamen, thalamus could potentially be biomarkers for predicting the efficacy of TMS.