Sensory recovery after constraint – induced movement therapy

Abstract

Constraint-Induced Movement Therapy (CIMT) involves intensive training of the affected arm, restraining of the less affected arm (immobilization) and shaping techniques. Previous reports have documented CIMT's clinical efficacy and its reorganization model. Since previous studies focused on motor recovery alone, it is still now unclear whether motor improvement is also based on sensory recovery. In former clinical studies subgroups of patients with sensory deficits showed more improvement of motor tests than patients with less affected sensory deficits. Considering this circumstance the underlying reorganization pattern is unclear by now. The aim of the current study was to investigate reorganization within the sensory network before and after CIMT. 7 chronic stroke patients with moderate hemiparesis and sensory deficits (no anaesthesia) were included to the study. CIMT contained six hours daily intensive training over two weeks with shaping technique and immobilization of the less affected arm. Motor tests (Wolf Motor Function Test, WMFT and Motor Activity Log, MAL) and fMRI were performed before and after CIMT. Passive movement of the affected and less affected hand was used to activate the sensory network. All patients improved their hand function significantly after CIMT. A correlation analysis between functional activation during passive hand movement of the affected hand and WMFT revealed a close relationship. This analysis showed that improvement of hand function was accompanied with less S1 activation and more thalamus activation. We suggest that functional interaction between S1 and thalamus plays an important role in hand function improvement after CIMT. In a post hoc analysis, probabilistic fiber tracking was used to connect two seed points between S1 and thalamus. Reorganization of improved hand function after CIMT is not only limited to the motor network, but also is based on reorganization within the sensory network.