A study of electrode placement at the cervical and upper thoracic nerve roots using an anatomic trans-spinal approach

Objective. Since 1996 we have placed temporary catheters at the cervical nerve roots in chronic pain patients for the treatment of radiculopathy and complex regional pain syndrome. We investigated the possibility of placing electrodes both at the cervical spinal nerve and dorsal root ganglion for the purpose of neuromodulation. Methods. Anatomic and technical feasibility studies were performed on 4 human cadavers to examine the placement of electrodes at the cervical nerve roots. We proposed a novel trans-spinal approach to the cervical and upper thoracic nerve roots. We tested various approaches and insertion techniques. We collected radiographic images of the essential steps involved in this technique. Results. Successful placement was accomplished in 3 of the 4 cadavers at the C3, C4, C5, C6, C7, C8, T1, and T2 nerve roots. For placement at C5 to T2, we used a trans-spinal approach entering at the corresponding contralateral interlaminar space. However, due to the anatomy of the cervical nerve roots, vertebral artery, cervical plexus, and occiput, it was necessary to use a different technique for the upper cervical nerve roots. For placement at the C3 and C4 nerve roots, we made the initial insertion between the C1 and C2 lamina using curved needles which were advanced in a caudal direction transversing the median plane of the spine to arrive at the contralateral inter vertebral foramen of either C3 or C4. We were unable to cannulate either C1 or C2 in any of the cadavers. The required equipment included fluoroscopy, contrast dye, directable guide wires, electrodes, and curved needles. Conclusions. In human cadavers, a percutaneous technique was successful in the placement of neurostimulator electrodes at the cervical and upper thoracic nerve roots using a novel trans-spinal approach. New smaller electrode systems that can be placed in a transforaminal position safely may be needed.