A surgical window to chronic pain relief
Neurostimulation of the posterior spinal cords has established itself as an effective therapy for patients with chronic neuropathic pain who do not respond to conventional treatments. In a recent surgery available in the online surgery app SurgSchool, the Dr. Miguel Barrera and Dr. Blanca Moreno, leading specialists in the Gregorio Marañón University Hospital in Zaragoza, successfully implanted a posterior cord neurostimulator, providing a valuable learning opportunity for the medical community.
This procedure, now accessible for viewing and detailed study in SurgSchool, not only demonstrates the technical expertise of surgeons, but also underlines the importance of anatomical precision and teamwork in highly complex interventions.
What is a Posterior Columnar Neurostimulator?
A posterior cord neurostimulator is an implantable medical device designed to modulate pain signals traveling through the spinal cord to the brain. It consists of one or more thin electrodes placed in the epidural space, over the posterior cords of the spinal cord, and a pulse generator (similar to a pacemaker) implanted subcutaneously, usually in the gluteal or abdominal region. By emitting gentle electrical impulses, the system interferes with the transmission of pain signals, often replacing them with a sensation of paresthesia (tingling) or, with more advanced technologies, no perceptible sensation other than the pain relief.
This therapy is primarily indicated for intractable chronic pain, such as failed back syndrome (persistent pain after spinal surgery), painful diabetic neuropathy, complex regional pain syndrome, and other conditions.
Surgery in Detail: Image-Guided Precision and Experience
This surgical video in SurgSchool allows us to delve into the key moments of the intervention performed by Dr. Barrera and Dr. Moreno.
1. Planning and Access
The surgical team begins by determining the approach strategy and optimal entry point. They identify key vertebral anatomical structures, such as the pedicles and spinous processes, which will serve as landmarks. From the outset, fluoroscopy (real-time x-ray equipment) is used to guide the procedure, confirm the planned trajectory, and verify vertebral levels, starting with the twelfth thoracic vertebra (T-12) and then focusing on T-12. Proper alignment and symmetry of the pedicles in the midline are noted.
2. Level and Entry Point Identification
Using continuous fluoroscopy, an accurate vertebral body count is performed to precisely locate the D-8 level. Once this level is confirmed, a reference is marked on the upper third of that vertebra, which will serve as a guide for entry. The skin incision is planned with consideration for both a trial phase of the stimulator and the final implantation of the system.
3. Preparation and Anesthetic Infiltration
Before making any incisions, local anesthesia is administered to the patient's skin. Additional anesthetic is then injected along the entire incision site, including the area where the subcutaneous pocket will be created to house the pulse generator. Throughout the procedure, the team maintains communication with the patient to ensure comfort, monitor any possible pain, and administer additional anesthesia if necessary.
4. Dissection and Insertion of the First Electrode
The medical team begins tissue dissection to access the epidural space. During this phase, they may encounter scar tissue if the patient has had previous surgeries in the area, which is carefully managed. The necessary space is dissected to allow for proper needle insertion and to ensure that the electrode, once placed, can assume the appropriate curvature without tension. The specific equipment for neurostimulation is prepared, which includes an octopolar epidural electrode (with eight contact poles), its internal guidewire, and a Tuohy (beveled) needle. The needle is introduced at a specific angle, approximately 45 degrees to the skin, and its advancement is constantly monitored using fluoroscopy. Reaching the epidural space is confirmed using the loss of resistance technique or by tactile sensation obtained with a palpator. Once in the correct space, the electrode is gently advanced through the needle. Its position is continuously verified under fluoroscopy, and attention is paid to any sensation the patient may experience.
5. Insertion of the Second Electrode and Adjustments
The placement of the second electrode is carefully planned to ensure it is an appropriate distance from the first and that both are well positioned, considering the available space in the spinal canal. This requires a new needle puncture, parallel to the previous one. A specific technique is used to direct the second electrode, which may involve making it contact and sliding it against the previously placed first electrode (the one most medial, or closest to the midline) to facilitate its ascent to the desired position.
6. Pocket Creation and Electrode Anchoring
Once the electrodes are in the optimal position, confirmed by fluoroscopy, the team creates a subcutaneous pocket, usually in the gluteal or abdominal region, where the pulse generator will be housed. The electrodes are firmly secured to the surrounding tissues (fascia or ligaments) using anchors and sutures to prevent them from shifting or migrating out of position over time. Special care is taken to ensure that the electrodes are not too superficially positioned under the skin or subjected to excessive tension.
7. Connection to the Generator and Closing
Finally, the electrode ends are connected to the pulse generator. The system's electrical impedance is checked. This measurement helps ensure a proper connection and that the electrodes and generator are functioning properly. Once the system's functionality is verified, the incision and generator pocket are closed in layers, using absorbable sutures for deep tissue and staples or sutures for the skin.
The Importance of Online Surgical Training with SurgSchool
This procedure, detailed captured and commented on in SurgSchool, offers an invaluable opportunity to:
- Medical students and residents: To understand anatomy, surgical steps, and real-time decision-making.
- Surgeons in training and specialists: To observe refined techniques, complication management, and the application of advanced technology from experts.
- Health professionals interested in pain management: To delve deeper into one of the most innovative therapies for chronic pain.
