The Mirror Illusion Increases Motor Cortex Excitability in Children With and Without Hemiparesis

Grunt, Sebastian; Newman, Christopher J; Saxer, Stefanie; Steinlin, Maja; Weisstanner, Christian; Kaelin-Lang, Alain (2017). The Mirror Illusion Increases Motor Cortex Excitability in Children With and Without Hemiparesis. Neurorehabilitation and neural repair, 31(3), pp. 280-289. Sage Publications 10.1177/1545968316680483

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Background Mirror therapy provides a visual illusion of a normal moving limb by using the mirror reflection of the unaffected arm instead of viewing the paretic limb and is used in rehabilitation to improve hand function. Little is known about the mechanism underlying its effect in children with hemiparesis. Objective To investigate the effect of the mirror illusion (MI) on the excitability of the primary motor cortex (M1) in children and adolescents. Methods Twelve patients with hemiparesis (10-20 years) and 8 typically developing subjects (8-17 years) participated. Corticospinal reorganization was classified as contralateral (projection from contralateral hemisphere to affected hand) or ipsilateral (projection from ipsilateral hemisphere to affected hand). M1 excitability of the hemisphere projecting to the affected (nondominant in typically developing subjects) hand was obtained during 2 different conditions using single-pulse transcranial magnetic stimulation (TMS). Each condition (without/with mirror) consisted of a unimanual and a bimanual task. Motor-evoked potentials (MEPs) were recorded from the abductor pollicis brevis and flexor digitorum superficialis muscles. Results MEP amplitudes were significantly increased during the mirror condition (P = .005) in typically developing subjects and in patients with contralateral reorganization. No significant effect of MI was found in subjects with ipsilateral reorganization. MI increased M1 excitability during active movements only. This increase was not correlated to hand function. Conclusion MI increases the excitability of M1 in hemiparetic patients with contralateral corticospinal organization and in typically developing subjects. This finding provides neurophysiological evidence supporting the application of mirror therapy in selected children and adolescents with hemiparesis.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine
04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic and Interventional Neuroradiology

UniBE Contributor:

Grunt, Sebastian, Steinlin, Maja, Weisstanner, Christian


600 Technology > 610 Medicine & health




Sage Publications




Anette van Dorland

Date Deposited:

15 Feb 2017 10:02

Last Modified:

05 Dec 2022 15:00

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

cerebral palsy; hemiplegia; mirror illusion; pediatric rehabilitation; transcranial magnetic stimulation




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