Functional MRI Of The Healthy And Injured Human Spinal Cord With Compoex Finger Tapping And Functional Electrical Stimulation

Backgroud:Spinal fMRI is a reliable tool for assessing neuron status and localizing activity in the spinal cord. In healthy volunteers the method has proved capable of demonstrating spinal cord neuronal activity in response to different stimulations. Finger tapping is a well-established stimulation task for mapping neuronal function in the human brain. Electrical stimulation is widely used as a diagnostic method in spinal cord diseases and has a long history as a rehabilitation tool for restoring mobility after spinal cord injury. The present investigation is to determine if spinal cord neuronal activation while undergoing a complex finger tapping task and electrical stimulation can be observed by spinal fMRI with a SSFSE sequence. Standard assessment of the condition of the spinal cord after an injury, or when affected by disease, is limited to the information that can be revealed by external signs. Information about the full extent of the cord's condition, and any changes as a result of clinical interventions, is becoming increasingly valuable as treating spinal cord injury (SCI) patients. The purpose of the work we are carrying out is to apply the noninvasive method of fMRI in the injured spinal cord.Purpose: Functional MR imaging of the human spinal cord was carried out on volunteers with complex finger tapping task and functional electrical stimulation, in order to detect image intensity changes arising from neuronal activity. Spinal fMRI was also applied in central cord syndrome patients to investigate the neuronal activity in the cervical spinal cord caudal and to develop spinal fMRI as a clinical diagnostic tool.Methods: Functional MR imaging data using single-shot fast spin-echo sequence (SSFSE) with echo time 42.4ms on a 1.5 T GE Clinical System were acquired in eleven healthy subjects performing complex finger tapping task and functional electrical stimulation. Investigation was also carried out in six patients with cervical spinal cord injury (central cord syndrome). Spinal cord activation was measured both in the sagittal and transverse imaging planes. Postprocessing was performed by AFNI (Analysis of Functional Neuroimages) software system.Results: Intensity changes (4.2%~13.2%) correlated with the time course of stimulation and were consistently detected in both sagittal and transverse imaging planes of the healthy spinal cord. The activated regions localized to the ipsilateral side of the spinal cord in agreement with the neural anatomy. Spinal cord activity was detected with Spinal fMRI in the spinal cord region, below the site of injury, in four spinal cord-injured subjects studied. In subjects with central cord syndrome, activity was consistently observed in the ipsilateral dorsal horn, corresponding to sensory input. Activity was also detected on the contralateral side of the cord and within the anterior median fissure, but was less prominent.Conclusion: Functional MR imaging signals can be reliably detected with finger tapping activity in the human spinal cord using SSFSE sequence. The anatomic location of neural activity correlates with the muscles used in the finger tapping task. We present the first application of Spinal fMRI to spinal cord-injured subjects and the first noninvasive demonstration of activity in the human spinal cord below the site of injury.