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All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human welfare and have been reviewed by the local institutional review board.
1. Implantation of the Multicolumn Lead
- Obtain the patient's informed consent after explaining the details of the surgical procedure, including the complications (infection 3–6%; serious neurological complications 0.54–1.71%; epidural hematoma 0.19–0.63%; spinal cord injury 0.022–0.067%; and cerebrospinal fluid leakage 0.05–0.001%).
NOTE: The long testing period required in Belgium is presumed to be the main reason for the higher infection rate (11%) observed in our institution, and we are currently trying to address this issue. This must be explained to the patient. - In addition to the above risks, which are similar to those associated with other spinal procedures, explain the other risks normally associated with the use of an implant, such as allergic or immune system responses to the implanted materials; lead, extension, or neurostimulator erosion through the skin or migration; and formation of reactive tissue around the lead in the epidural space that can result in delayed spinal cord compression and paralysis, requiring surgical intervention. Time to onset can range from weeks to many years after implant.
NOTE: The neurological complication rates for percutaneous dorsal column stimulation leads are slightly higher (infection 3–6%; serious neurological complications 0–2.35%; epidural hematoma 0.75%; spinal cord injury 0.03–2.35%; and cerebrospinal fluid leakage 0.3%). - If the patient doesn't have any contraindication, conduct an MRI (Magnetic resonance imaging) to rule out any anomaly of the conus medullaris projection such as spinal dysraphism or other congenital spinal cord anomalies.
- Perform antibiotic prophylaxis 30 min before incision using a single intravenous (IV) dose of Cefazolin, 50 mg/kg, with a maximum of 2 gm, through a 16 G needle placed in a peripheral route.
- With the patient under general anesthesia (use 0.1 µg/kg Sunfentanil, 2 mg/kg Propolipid 1%, 0.3 mg/kg Ketamine Hydrochloride (see Table of Materials), and 0.3 mg/kg Rocuronium) and in the prone position, define the incision site between the spinous processes of T10 and T11 under fluoroscopic assistance.
- Infiltrate the incision site with 5 mL of a 20 mL solution of 0.5% Bupivacaine and 1:200,000 adrenaline (see Table of Materials).
- Incise until the thoracic aponeuroses are revealed.
- Dissect the paravertebral musculature on both sides of T10's supraspinous process and place the retractor.
- Resect the supraspinous and interspinous ligaments and dissect the lamina of T10 (5 mm on each side and 5 mm in the craniocaudal direction).
- Before inserting the lead, perform a partial laminectomy of T10 to create enough space to allow the insertion of the lead (no need to remove the entire lamina).
- Insert the phantom lead into the epidural space while keeping the insertion of the flavum ligament on the upper part of the T11 lamina intact.
NOTE: This T11 lamina is used as a guide for the insertion of the lead into the epidural space. - Place the lead as medially as possible under fluoroscopic guidance. The final lead's position is reached when placed midline in the projection of the bodies of T8–T9 under fluoroscopic control.
- Fix the lead to the interspinous ligament of T11 by doing a single interrupted stitch.
- Tunnel the extensions from your operative field to the lateral side of the back (often the right one) by using the tunneling tool provided by the company, and then connect them to the lead.
- Check fluoroscopically to be sure the lead has not moved and is still in the epidural space, midline, in the projection of T8–T9.
- Remove the retractor and make sure there is no bleeding.
- Suture the musculo-aponeurotic layer by means of simple interrupted stitches of braided synthetic absorbable suture material (see Table of Materials).
- Connect the two intrinsic external extensions to the two extrinsic external extensions. Tunnel them in the subcutaneous fat in such a way that they exit through the skin 15 cm laterally to the incision site.
NOTE: The choice of the side is discussed preoperatively with the patient and depends on the implantation location of the internal pulse generator. - Wrap the intrinsic and extrinsic extensions and suture the subcutaneous layer by means of simple interrupted stitches of braided synthetic absorbable suture material (see Table of Materials).
- Make a dermic subcuticular suture using finer absorbable 3/0 suture material (see Table of Materials) and apply antiseptic and bandages. During this step, administer a single IV dose of 1g Paracetamol and 100 mg Tradonal.