Asymmetrical localisation of the motor cortex after perinatally acquired intracerebral hemorrhage: Volume shift versus neuroplasticity

Introduction: In early acquired unilateral brain lesions an interhemispheric shift of the primary motor cortical representation to the contralesional hemisphere can be observed. A neuroplastic reorganization within the lesional hemisphere has not been described yet. We report on the unusual case of a 12-year old girl with an apparently destroyed central region due to perinatally acquired right-sided intracererbal hemorrhage, left-sided spastic hemiparesis, surprisingly good residual function of the left hand and symptomatic-focal epilepsy.

Diagnostic:

MRI: large right parieto-occipital defect including the area opposing the left contralesional central region; volume-reduction, diffuse gliosis of the white matter with a frontal maximum, reduced myelinisation, hippocampal sclerosis in the right hemisphere.

Transcranial magnetic stimulation (TMS): a) lesional hemisphere: intact motor evoked potentials (MEP) of the right hand (latency 19.7ms). b) contralesional hemisphere: intact MEPs of the contralateral, non-paretic hand (latency 21.5ms) and MEPs of low amplitude of the ipsilateral paretic hand (latency 24.7ms)

Functional MRI: movement of the paretic left hand leads to an activation of the right hemisphere, which is markedly anterior of the activation of the left hemisphere during movement of the non-paretic right hand.

Fibre tracking: asymmetrical course of the bilaterally persistent pyramidal tracts with a marked frontal shift within the lesional right hemisphere.

Discussion: The combination of the functional methods shows a regular organisation of the primary motor representation of the lesional hemisphere that is represented anteriorly due to volume-shifting. The fMRI does not indicate a functional participation of the ipsilateral cortico-spinal projections to the paretic left hand. Concerning the therapy-refractory epilepsy a hemispherotomy was discussed, but a severe deterioration of the motor function of the paretic left side would have to be expected. As the epileptic focus is located temporo-occipitally, a circumscribed resection in this region seems to be a promising alternative.