Modified and systematically-designed installation procedure for spinal cord stimulation in the decubitus position under local anesthesia: a introductory technical case report

Abstract

Introduction: Spinal cord stimulation (SCS) is sometimes preferable in some refractory chronic lower back pain (LBP) pathologies. SCS involves an insertion of electrode leads into the epidural space in the prone position under local anesthesia, followed by neurostimulator implantation under local/general anesthesia. These continuous procedures can cause transient post-operative LBP exacerbation and to make temporary pockets that will store redundant leads in it with some risk of subcutaneous irritation and infection in addition to making extra incisions. We introduce a modified simpler method for SCS implantation, systematically designed to be performed only under local anesthesia in a decubitus, non-prone position.

Materials and methods: An 81-year-old patient with FBSS was treated. A physician was able to insert SCS leads with ease while the patient was in a decubitus position. The patient was comfortable, under totally local anesthesia, and the procedure produced no extra subcutaneous pockets.

Result: The patient felt almost no LBP and reported no pain exacerbation during the operation. The SCS installation provided the patient with great improvement in both her lower back (NRS from 8 to 0-1) and leg (from 7 to 2) pain with a great improvement in her daily life activities. No adverse events were observed during the perioperative period.

Conclusion: The modified SCS insertion method enabled us to achieve both intraoperative pain relief and complete SCS implantation in a minimally invasive manner.

Keywords: Spinal cord stimulation (SCS); decubitus position; failed back surgery syndrome (FBSS); less invasive; lower back pain (LBP).

Figure 1

Radiological studies of the presented case. A, B. Plain lumbar radiograph. C. Magnetic resonance imaging. Radiological studies showed spondylosis with decreased disc height in and multiple bulging intervertebral discs with severe L3-4 foraminal stenosis.

Figure 2

Preoperative setting for lead placement. The patient was laid down in a decubitus position on her right side. A. The location of an anterior pocket, which was to contain the redundant leads during the neurostimulation trial period, was determined by placing a stimulator mock-up. The pocket was also used as a pocket for a neurostimulator. B. The length of the lead trajectory from the pocket was measured and confirmed via a scheduled incision on the back. The levels and location of the L3 pedicles and L3-4 interlaminar were marked up prior to fluoroscopic guidance, as the L1-2 interlaminae space was the site that had been predetermined for approach into the epidural space. A paper clip was applied at the level of T8 as a marker (*). C, D. The patient was draped in a usual sterile manner, and a wide opening was made in the drapery to expose the navel to the right iliac bone so that sufficient area was secured for the operation.

Figure 3

Placing the stimulation leads in the decubitus position. A. A Tuohy needle was inserted using a paramedial approach via a midline incision, and the epidural space was confirmed using a standard loss-of-resistance technique. B. The leads were inserted to the initial target placement site under fluoroscopic guide. Notice the marker for the T8 level (a paper clip) shown in the fluoroscopic display. C. After insertion of the leads, optimal lead positions were determined during the intraoperative test stimulation. D. After optimal lead placement was determined, the leads were anchored to fascia using an anchoring device.

Figure 4

Subcutaneous lead introduction to complete the trial placement (A-E). The dotted line indicates the route of the subcutaneous lead. (F) Shows the scheme of the whole trajectory. (A) After anchoring the leads to the fascia, they were introduced to the temporary hole at the flank with enough local anesthesia along the tunneling route. (B) The proximal end of the extension of the lead was gently introduced through the passing straw to the temporary hole. Notice that the other surgeon was simultaneously making an anterior pocket on the contralateral side. (C) Another tunnel was made from the temporary hole to the anterior pocket using the tunneling tool, and this was followed by introduction of the lead to the anterior pocket. (D, E) After connecting the implanted lead to the extension leads (white circle), we retraced the trajectory from the anterior pocket to the temporary hole and introduced the extension leads.

Figure 5

Neurostimulation system installation. (F) Shows the scheme of the installation. (A) The patient was placed again in a decubitus position. *: anterior pocket, arrowhead: extension lead from the temporary hole. (B) Under local anesthesia, extension leads were pulled out from inside of the pocket. (C) Extensions were removed, followed by the connection and placement of the neurostimulator system. (D, E) Post-operative lumbar radiograph with well-positioned leads.

Figure 6

Anatomical confirmation using a lumbar bone model. A. Neutral position. B. Flexion position. Trans-interlaminar space was increased in flexion (b, L_F) compared with neutral or extension (a, L_N). The enlarged trans-interlaminar space enabled us to achieve a more sharp and controllable insertion angle (θ_F) compared with the neutral (θ_N) position. This also prevented damage to the leads and dura mater caused by too much angulation at the epidural insertion point.