Neuropediatrics 2005; 36 - V13
DOI: 10.1055/s-2005-867972

Hemispheric dissociation between motor and sensory hand representations in congenital hemiparesis: TMS, fMRI, MEG

M Staudt 1, C Braun 2, C Gerloff 3, W Grodd 4, I Krägeloh-Mann 1
  • 1Universitätsklinik für Kinderheilkunde und Jugendmedizin, Neuropädiatrie und Entwicklungsneurologie, Tübingen
  • 2Institut für Medizinische Psychologie und Verhaltensbiologie, MEG-Zentrum, Tübingen
  • 3Hertie-Institut, Neurologische Universitätsklinik, Tübingen
  • 4Radiologische Universitätsklinik, Abt. Neuroradiologie, Sektion experimentelle MRT des ZNS, Tübingen

Objectives: Many children with congenital hemiparesis possess ipsilateral cortico-spinal projections, which enable the contra-lesional hemisphere to exert direct motor control over the ipsilateral, paretic hand. A previous TMS and fMRI study on congenital hemiparesis caused by unilateral periventricular brain lesions could demonstrate that all patient with such ipsilateral cortico-spinal pathways nevertheless showed strong fMRI activation of the central (Rolandic) cortex of the affected hemisphere during active movements with the paretic hand, even when no motor tracts could be identified arising in the affected hemisphere. The purpose of the present study was to further characterize these unclear fMRI activation sites.

Material and Methods: Two additional methods were applied: (1) fMRI during passive hand movements, i.e. repetitive flexion/extension of the fingers of the paretic hand exerted by the experimenter; (2) magnetoencephalography (MEG) during tactile stimulation (2Hz) of the paretic thumb.

Results: In all four patients, passive movement of the paretic hand elicited fMRI activation in the contralateral (affected) hemisphere, which was very similar to that observed during active hand movements, whereas the ipsilateral activation of their “reorganized primary motor representations“ disappeared. Accordingly, MEG demonstrated the first cortical response to tactile stimulation of the paretic thumb in the Rolandic cortex of the affected hemisphere, with a latency of approximately 20 msec.

Conclusions: All four patients with congenital hemiparesis due to unilateral periventricular lesions and an ipsilaterally reorganized primary motor representation of the paretic hand in the intact hemisphere showed a preserved primary somatosensory representation of the paretic hand in the affected hemisphere. The functional consequences of this hemispheric dissociation between primary motor and primary somatosensory representations require further study; they might be related to the sensorimotor deficits of such patients.