Contact dissociation from paddle leads: a report of two cases.

Case 1 A 60-year-old white male developed neck and bilateral shoulder pain two and a half years ago. There was no history of trauma. He had numbness and paresthesias along the ulnar border of his left forearm and in his left ring and little fingers. Pinprick sensibility was decreased along the medial and lateral borders of his left forearm and in his left middle finger. Reflexes and motor testing were normal. A CT myelogram of his cervical spine showed small disc bulges at C3-4, C4-5, and C5-6 without neural impingement. He had been treated with pain medications and epidural blocks without improvement. He had a spinal cord stimulator trial with greater than 50% improvement in his pain. He underwent implantation of a Boston Scientific permanent percutaneous spinal cord stimulator (Boston, MA, USA) and placement of a rechargeable battery above the left hip onMay 4, 2011. Onemonth later, he lost stimulation. The percutaneous leads had migrated. On June 20, 2011, he underwent removal of the percutaneous leads and implantation of a Boston Scientific paddle lead through a laminectomy at C4. He was kept in a soft cervical collar for six weeks. AP and lateral X-rays of his cervical spine obtained at that time are shown in Figure 1. He had good coverage and pain control for 14 months, after which time he lost coverage in his neck and left upper extremity. There was no history of trauma. His implantable pulse generator (IPG) was found to be functioning normally, and the impedances were normal. A lateral X-ray is shown in Figure 2. The lateral X-ray obtained at six weeks after his first revision, shown in Figure 1, was made in slight flexion. The implant appears relatively straight. The X-ray obtained at 14 months post-revision, shown in Figure 2, was made in a more neutral position. Note the deformation of the paddle. The top of the paddle is still at the superior margin of the lamina of C3, and the bottom of the paddle is still at the superior margin of the spinous process of C5, to which the implant was anchored. On December 14, 2012, the patient underwent removal of the Boston Scientific paddle and implantation of a St. Jude (Plano, TX, USA) Exclaim lead over the ring of C1. The Boston Scientific IPG was discarded, and a St. Jude IPG was implanted into a new pocket over the right hip. Since this was a second revision procedure, great care was taken during the dissection. The tails of the Boston Scientific leadwere traced to the paddle. As the scar over the dorsal surface of the bottom half of the paddle was incised, the inferior half of the lead popped up into the surgical field. Half the contacts were noted to be separated from the ventral surface of the paddle and were embedded in the fibrous sheath that had formed around the lead. The wires remained in the silastic paddle and did not appear to be attached to the contacts, as would have been expected based on the preoperative impedance testing. The lead and all but one of the disengaged contacts were removed. Themost cephalad dissociated contact could not be removed without performing a laminectomy of C3 and was left in place (Figure 3). The patient is getting satisfactory coverage and pain control with his St. Jude implant.