Cortical activation pattern in hemiparetic patients with pontine infarct

No prior study has reported on the cortical activation pattern in hemiparetic patients with a pontine infarct. The aim of this study was to investigate the cortical activation pattern of hemiparetic patients with a pontine infarct, using functional MRI scanning (fMRI).

Fifteen consecutive patients who showed severe weakness at onset due to a pontine infarct were recruited. The motor function was assessed at the time of the onset of stroke and fMRI scanning was performed (on average 8.9 months after stroke onset). The fMRI was performed during a motor task of timed hand grasp-release movements. From the fMRI, the laterality index was calculated to assess the relative activity in the ipsilateral versus the contralateral primary sensorimotor cortex (SM1).

All patients except for 2 (bilateral SM1 activation) showed contralateral SM1 activation without ipsilateral SM1 activation associated with the affected hand movements. The average laterality index for the affected hand movements among all patients was 0.97.

The fMRI results showed that primarily the contralateral SM1 was activated during affected hand movements. Therefore, it appears that the motor function of the affected hand, in patients with a pontine infarct, recovers mainly via the lateral corticospinal tract.