Neuromagnetic investigation of somatosensory cortical reorganization in hemiplegic patients after thalamic hemorrhage

[Purpose] The purpose of the present study was to investigate somatosensory cortical reorganization in terms of source locations of somatosensory evoked magnetic fields (SEFs) in hemiplegic patients after thalamic hemorrhage. [Subjects] Nine hemiplegic patients after thalamic hemorrhage participated in this study. [Methods] SEFs in the affected and healthy hemispheres were obtained with alternative current stimulation of the left and right median nerves at the wrist within 72 hours (acute stage) and at three months (chronic stage) after the onset of thalamic hemorrhage. After source estimation using a single equivalent current dipole model was performed to two median nerve SEF components, the source location changes of corresponding components between the acute and chronic stages were investigated. [Results] In the affected hemisphere, no patients showed significant SEF source location changes between the acute and chronic stages. In the healthy hemisphere, three patients showed significant SEF source location changes between the acute and chronic stages. [Conclusion] The significant SEF source location changes in the healthy hemisphere between the acute and chronic stages might reflect somatosensory cortical reorganization based on dependence on the non-affected upper extremity (UE) due to affected UE dysfunction in activities of daily living (i.e. use-dependent plasticity).