Neuroplasticity after constraint induced movement therapy: Patients with ipsilateral cortico-spinal organisation

Objective: Constraint-Induced Movement Therapy (CIMT) is a functional approach focussing on hand motor improvement in hemiparetic patients. Here, we describe neuroplastic effects after two weeks of CIMT in patients with ipsilateral cortico-spinal (re-)organization.

Methods: 8 patients with congenital hemiparesis, unilateral periventricular white matter lesions and ipsilateral cortico-spinal projections to the paretic hand were included (mean age: 16.6 years). The Wolf motor function test (WMFT) was used to evaluate hand function before and after treatment. fMRI during repetitive active movements of the paretic hand was performed in all patients. Furthermore changes of motor evoked potentials (MEP) after single and paired pulse (interstimulus intervals: 2, 3, 10 and 20ms) transcranial magnetic stimulation (TMS) were studied.

Results: After CIMT patients showed an improvement in the quality section of WMFT (pre 3.32±0.35, post 3.86±0.25, p=0.007) but not in the time dimension (pre 2.22±0.79, post 2.82±0.76, p=0.051). A decrease in fMRI activation was observed in the ipsilateral cortical hand representation during active movement of the paretic hand. A parallel decrease was seen in single pulse TMS MEP amplitude (pre 0.90±0.21 mV, post 0.41±0,32 mV, p=0,035). Furthermore, these patients showed a significant intracortical disinhibition by factor 1.95 (1.63–2.3, KI 95%; log(ICI) 0,47–0,85, KI 95%) compared to the representation of the non-paretic hand.

Conclusion: Patients with unilateral periventricular white matter lesions and ipsilateral cortico-spinal projections to the paretic hand did not show a clear functional benefit after CIMT. Whereas disinhibition after training is in accordance to the findings after hand motor training in healthy subjects, these patients showed paradox neuroplasticity in form of decreased motor cortex activity in TMS as well as in the fMRI.