We wanted to assess the cerebral activation of the motor function after deep cortical (lentiform nucleus and thalamus) infarction.

We studied the motor function of eight right-handed deep cortical infarcted patients (mean age, 61 years; 7 men and 1 woman) who suffered a single unilateral deep cortical (lentiform nucleus or thalamus) infarction. The grade of muscle power by the grading system of the Medical Research Council was II in two patients, III in three patients and IV in three patients. All the MRI experiments were performed with a 1.5T scanner. The fMRI protocol consisted of eight alternating periods of task performance and rest. The activation tasks consisted of finger movements. Data analysis of activated area and calculation of the activated volumes in sensorimotor cortex were done.

For the six lentiform nucleus acute infarction patients, one right hemiparetic patient (MRC Grade: II), and only the right sensorimotor cortex (the unilateral non-lesion side) were activated. In five (MRC Grade: III-IV) of the six lentiform nucleus infarcted patients, bilateral activations of the primary sensorimotor cortex were recorded. In four of the five bilaterally activated patients, extended activations in the lesion side sensorimotor cortex were observed. In the two right thalamic infarction patients, bilateral activations of the primary sensorimotor cortex were recorded. One patient (MRC Grade: II) was observed to have an extended activation in the non-lesion side sensorimotor cortex. On the follow up fMRI done on this patient after 40 days (MRC Grade: III at that time), the activated volumes of both sensorimotor cortexes were increased. The activated volume in the lesion side sensorimotor cortex was more than that in the non-lesion side sensorimotor cortex. The other patient (MRC Grade: IV) was observed to have extended activation in the lesion side sensorimotor cortex.

fMRI allows for the study of the motor function in deep cortical infarction. We were able to investigate the differences in motor activation according to the individual MRC Grades. fMRI may be a useful tool to monitor and study deep cortical infarction, and it may be important to help us understand the function of the deep cortical areas.