Functional MRI of the spinal cord: will it solve the puzzle of pain?

Whether stimulation of the median nerve could evoke an fMR imaging response at 1.5 T in the cervical spinal cord was investigated and the response pattern was compared with that obtained by fist clenching.

Eleven subjects performed the fist-clenching task and in seven of them electrical stimulation was also applied. fMRI was performed using a T2* sensitive echo-planar imaging sequence gated by the heartbeat signal. A dynamic cardiac-gated T2*-weighted imaging sequence was used to quantify cervical spinal cord activation. Cord activation was measured in the sagittal and transverse imaging planes.

With the fist-clenching task, activation of the spinal cord in the cervical intumescence could be seen in seven of eleven subjects in the sagittal plane and in six of nine subjects in whom axial images were acquired. When median nerve stimulation was applied, cord activation was seen in the sagittal images in five out of seven, and in the axial plane in two out of six subjects. A consistent cross-sectional localization of the activity measured in the spinal cord was not detected, either in terms of the right and left sides or in terms of the posterior and anterior directions.

In the sagittal plane, median nerve stimulation at the elbow can evoke an fMR imaging response in the lower cervical spinal cord. The activation pattern was comparable with that obtained by fist clenching.