The relationships between trunk function and the findings of transcranial magnetic stimulation among patients with stroke

In this study, we investigated the relationship between the motor evoked po tentials obtained from trunk muscles and the clinical function of trunk mus cle. Twenty patients with unilateral hemispheric stroke and 11 healthy adul ts were examined. The responses of the bilateral external oblique muscles a nd the erector spinae muscles to the magnetic stimulation of multiple sites over both cortical hemispheres were recorded. Trunk muscle performance was assessed using the Trunk Control Test and Stroke Impairment Assessment Set . In the stroke group, stimulation of the affected hemisphere resulted in a motor evoked potential in only one patient, while the other 19 stroke pati ents produced no response to stimulation of the affected hemisphere. Stimul ation of the unaffected hemisphere evoked bilateral responses in 19 patient s. Further, stimulation of the unaffected hemisphere in the stroke group pr oduced larger motor evoked potentials in the ipsilateral muscles than the m otor evoked potentials recorded in the ipsilateral muscles of the control g roup. The clinical assessment scores of trunk function (i.e. Trunk Control Test and trunk items of Stroke Impairment Assessment Set) were correlated w ith the amplitudes of the motor evoked potentials of the ipsilateral extern al oblique muscle that were evoked by stimulation of the unaffected hemisph ere. Our results suggest that the recovery of trunk function after stroke i s associated with an increase in ipsilateral motor evoked potentials in the external oblique muscle upon stimulation of the unaffected hemisphere, sug gesting a role for compensatory activation of uncrossed pathways in recover y of trunk function.