Task-specific brain reorganization in motor recovery induced by a hybrid-rehabilitation combining training with brain stimulation after stroke.

Recently, we have developed a new hybrid-rehabilitation combining 5Hz repetitive transcranial magnetic stimulation and extensor motor training of the paretic upper-limb for stroke patients with flexor hypertonia. We previously showed that the extensor-specific plastic change in M1 was associated with beneficial effects of our protocol (Koganemaru et al., 2010). Here, we investigated whether extensor-specific multiregional brain reorganization occurred after the hybrid-rehabilitation using functional magnetic resonance imaging. Eleven chronic stroke patients were scanned while performing upper-limb extensor movements. Untrained flexor movements were used as a control condition. The scanning and clinical assessments were done before, immediately and 2 weeks after the hybrid-rehabilitation. As a result, during the trained extensor movements, the imaging analysis showed a significant reduction of brain activity in the ipsilesional sensorimotor cortex, the contralesional cingulate motor cortex and the contralesional premotor cortex in association with functional improvements of the paretic hands. The activation change was not found for the control condition. Our results suggested that use-dependent plasticity induced by repetitive motor training with brain stimulation might be related to task-specific multi-regional brain reorganization. It provides a key to understand why repetitive training of the target action is one of the most powerful rehabilitation strategies to help patients.

Recovery of upper-limb function due to enhanced use-dependent plasticity in chronic stroke patients.

Patients with chronic stroke often show increased flexor hypertonia in their affected upper limbs. Although an intervention strategy targeting the extensors of the affected upper limb might thus be expected to have benefits for functional recovery, conventional repetitive motor training has limited clinical utility. Recent studies have shown that repetitive transcranial magnetic stimulation could induce motor recovery. The present study tested whether 5 Hz repetitive transcranial magnetic stimulation of the upper-limb area of the primary motor cortex, combined with extensor motor training, had a greater effect on motor recovery than either intervention alone in stroke hemiparesis. Nine patients with chronic subcortical stroke and nine age-matched healthy subjects completed the crossover study. In separate sessions, we examined the single intervention effect of repetitive wrist and finger extension exercises aided by neuromuscular stimulation, the single intervention effect of 5 Hz repetitive transcranial magnetic stimulation and the combined effect of the two interventions. The motor functions were evaluated behaviourally in patients (Experiment 1) and electrophysiologically in healthy subjects (Experiment 2), both before and after the intervention. In addition, we tested the long-term effect by repeating the combined interventions 12 times in patients (Experiment 3). The motor functions were measured again 2 weeks after the end of the repetitive intervention period. In Experiment 1, the combined intervention, but neither of the single interventions, resulted in an improvement of extensor movement (P < 0.0001) and grip power (P < 0.05), along with a reduction of flexor hypertonia (P < 0.01), in their paretic upper limbs. In Experiment 2, only the combined intervention resulted in selective plastic changes of cortico-spinal excitability (P < 0.01), motor threshold (P < 0.001) and silent period (P < 0.01) for the extensors. In Experiment 3, we also confirmed long-term beneficial effects of the combined intervention in patients. These findings indicate that combining motor training with repetitive transcranial magnetic stimulation can facilitate use-dependent plasticity and achieve functional recovery of motor impairments that cannot be attained by either intervention alone. This method could be a powerful rehabilitative approach for patients with hemiparetic stroke.

A new evaluation method for upper extremity dexterity of patients with hemiparesis after stroke: the 10-second tests.

We developed a new, sensitive evaluation method for upper extremity dexterity in patients with hemiparesis after stroke. This evaluation method consists of three types of test: the Finger Individual Movement Test, Hand Pronation and Supination Test, and Finger Tapping Test. In each test, the number of movements that can be performed during a 10-s period is measured. Data obtained by these 10-s tests were compared with those obtained by the Nine-Hole Peg Test (NHPT), and the usefulness of this new method was evaluated. In patients with hemiparesis after stroke, three types of 10-s test and NHPT were performed for the upper extremities on both the affected and unaffected sides. Simple correlation analysis and multiple regression analysis of data obtained by the three types of test and NHPT were performed using the affected/unaffected ratios. Twenty patients participated (54-85 years; 0.23-43.83 months after stroke) with mild upper extremity hemiparesis. Significant correlations exist between Finger Individual Movement Test and NHPT data (r=-0.584, P=0.0068) and between Hand Pronation and Supination Test and NHPT data (r=-0.707, P=0.0005). The multiple regression analysis model using the three types of 10-s test as explanatory variables was significant (P=0.0025) and explained 52.4% of the NHPT results. A significant association was observed between NHPT and the 10-s tests. The 10-s tests require no special examination instruments and can be readily performed in a short period. This evaluation method consisting of the 10-s tests can be a new clinical parameter of dexterity in patients with hemiparesis after stroke.