Where Is a Spinal Cord Stimulator Placed?

A spinal cord stimulator is placed in the epidural space of the spinal canal, with thin electrode leads positioned against the back (dorsal) side of the spinal cord. Imaging studies confirm that in most patients the electrodes sit in the posterior third of the canal, just outside the protective membrane surrounding the spinal cord itself. A separate battery unit, called the pulse generator, is implanted under the skin in a different part of the body, typically the lower back or buttock area. The exact spinal level where the leads land, the type of lead used, and where the generator goes all vary depending on where your pain is, what kind of pain it is, and your surgeon’s preferred approach.

Inside the Spinal Canal

The spinal cord runs through a bony tunnel formed by your vertebrae. Between the bone and the cord’s outer membrane sits the epidural space, a narrow gap filled with fat, blood vessels, and connective tissue. This is where stimulator leads are placed. A CT-based study of patients with implanted devices found that on the large majority of scans, electrodes sat in the epidural space within the posterior third of the spinal canal, meaning they rested behind the spinal cord rather than beside or in front of it.¹ That dorsal positioning is intentional. The electrical contacts need to be close to the dorsal columns of the spinal cord, which carry sensory signals up to the brain. Stimulating those columns is the core mechanism behind pain relief.

It was not always done this way. The very first spinal cord stimulator, implanted in 1967 by physician Norman Shealy and his engineering collaborators, used an electrode placed in the subarachnoid space, directly against the spinal cord beneath the protective membranes. That worked for pain relief, but putting hardware inside the fluid-filled space surrounding the cord created serious complication risks. By the 1970s, the field had universally shifted to epidural placement, which keeps the electrode outside the membranes and dramatically reduces the chance of damaging the cord.²

Which Spinal Level Gets the Lead

The lead does not go to a single standard location for every patient. The electrode is positioned at the spinal cord segments that align with each person’s specific pain distribution.³ For the most common indication, chronic low back and leg pain after spinal surgery, leads typically land in the mid-to-lower thoracic spine. One multicenter study placed leads so that the active contacts crossed the T8/T9 disc space and the T9/T10 vertebral junction, which are standard landmarks for covering low back and bilateral leg pain.⁴

For complex regional pain syndrome affecting an arm or hand, leads may be placed much higher, at the C2 vertebral level in the upper cervical spine.⁵ When the pain source is a spinal cord injury itself, the lead may be placed on the lesion, below it, or above it, depending on where the pain is actually felt rather than where the damage occurred.³ This flexibility is one reason spinal cord stimulation can address such different pain conditions.

Percutaneous Leads vs. Surgical Paddle Leads

There are two fundamentally different ways to get a lead into the epidural space, and each determines the kind of surgery involved.

Percutaneous leads are thin, cylindrical wires threaded through a needle under local anesthesia and guided by fluoroscopy (live X-ray). You are awake or lightly sedated during the procedure because the surgeon needs your feedback. A technique called paresthesia mapping sends test pulses through the lead while it is being positioned, and you report where you feel the tingling. This real-time adjustment lets the surgeon fine-tune the lead’s final resting spot to cover your specific pain area.⁵ The tradeoff is that cylindrical leads contact the spinal cord over a smaller surface area.

Surgical paddle leads are flat, wider arrays of electrodes that require a small opening in the bone (a laminotomy or laminectomy) to slide into the epidural space. This is done under general anesthesia, so there is no real-time patient feedback during placement. Surgeons rely instead on anatomical landmarks. The wider contact surface of a paddle lead can provide more stable stimulation coverage, and the flat shape helps keep the lead from rotating out of position. One technique, called en bloc laminoplasty, removes the bone as a single piece and then replaces it after the paddle is positioned. The preserved bone acts as a buttress behind the lead, helping hold it in place and providing a protective barrier.⁶

Where the Pulse Generator Goes

The leads in your spine connect via extension wires to a pulse generator, which is the battery-powered device that actually produces the electrical signals. This generator is implanted in a pocket of tissue under the skin, away from the spine. Common locations include the upper buttock, the lower flank or abdomen, and the posterior chest wall (the upper back below the shoulder blade). Your surgeon picks a spot based on your body type, lifestyle, and sometimes personal preference.

Location matters more than you might think, because “pocket pain,” or discomfort at the generator site, is a real and sometimes persistent problem. A single-center study found that the lowest rates of generator-site pain occurred with posterior chest wall placement, while abdominal implants had the highest rates.⁷ A separate analysis found that patients who developed pocket pain were more likely to have the generator placed in the buttock, and that thicker generators were associated with more pain at the site.⁸ If you are being offered a choice of generator location, it is worth asking your surgeon about their experience with pocket-related complications at each site. The buttock is popular because it is easy to access surgically and out of the way cosmetically, but the evidence suggests it may carry a higher pocket-pain risk than other spots.

The Trial Phase Before Permanent Placement

Almost no one goes straight to a permanent implant. Standard practice involves a trial period, usually lasting about a week, during which temporary leads are placed in the epidural space and connected to an external pulse generator worn on a belt. You go about your daily routine and track whether the stimulation reduces your pain enough to justify permanent surgery. A trial can be done with a simple percutaneous temporary lead or with a permanently anchored lead that is placed through a small open surgical procedure and secured to tissue.⁹ The temporary approach is less invasive but the leads can shift during the trial. The anchored approach is more stable but means a slightly bigger procedure even at the trial stage.

If the trial is successful, permanent implantation follows. The trial leads may be removed and replaced with new permanent leads, or in some protocols, the anchored trial leads are kept and simply connected to a fully implanted generator. Either way, the spinal target for the permanent leads is the same location that worked during the trial.

Lead Migration and How Surgeons Try to Prevent It

One of the most common mechanical complications is lead migration, where the electrode shifts from its intended position over time. Even a few millimeters of movement can change which nerve fibers are being stimulated, reducing pain relief or causing unwanted sensations. This can happen during the trial phase as well as after permanent placement. A study of lead migration during trials found no clear predictor of which patients were most likely to experience it. Factors like the fixation technique used, the surgeon’s experience level, the device manufacturer, or patient characteristics such as age, sex, height, or BMI did not correlate with the likelihood of significant movement.¹⁰

Despite the lack of a single proven prevention method, surgeons use a variety of anchoring strategies to reduce migration risk. Standard practice involves suturing the lead to the deep tissue (fascia) near where it exits the spine. Some surgeons have developed more aggressive fixation techniques, including the use of small screws and washers as a secondary anchor point to add mechanical stability.¹¹ With paddle leads, the broader shape and the surrounding bone (especially when a laminoplasty technique is used) provide inherent resistance to shifting.⁶ Modern programming capabilities can also compensate for small degrees of migration by adjusting which contacts are active, which is less invasive than reopening the wound to reposition the lead.

Dorsal Root Ganglion Stimulation

A related but distinct approach targets the dorsal root ganglia (DRG), which are clusters of nerve cell bodies sitting just outside the spinal cord at each vertebral level. DRG stimulation uses leads that are threaded through the epidural space and then steered laterally into the bony opening (foramen) where a spinal nerve exits the canal. The lead tip is positioned directly over the dorsal surface of the ganglion.¹² This is a more targeted form of stimulation, useful for localized pain in specific areas like the foot, knee, or groin that traditional spinal cord stimulation sometimes struggles to cover.

DRG lead placement is technically trickier than standard spinal cord stimulation because the target is smaller and the path through the foramen is tight. After the lead is advanced into position and confirmed with imaging, the surgeon creates tension loops (S-shaped curves of extra lead wire) in the epidural space before anchoring the lead to the deep tissue.¹³ These loops act as strain relief, absorbing movement from daily activities so the lead tip stays in place rather than being pulled out of the foramen. Migration and lead fracture are particular concerns with DRG stimulation precisely because the lead must navigate a narrow anatomical corridor.

Scarring and What Happens Around the Leads Over Time

Once leads are in the epidural space, the body gradually forms a thin layer of fibrous tissue around them, much like it does around any implanted device. In most patients this is harmless and may even help stabilize the lead. But in rare cases, excessive scar tissue can become a problem. Case reports have documented patients developing myelopathy, a condition where the growing fibrous mass compresses the spinal cord enough to cause neurological symptoms like weakness or sensory changes. One review of previously reported cases found that this complication has occurred at both mobile cervical levels and the relatively stationary thoracic spine, suggesting that spinal movement alone does not fully explain why some patients develop problematic scarring.¹⁴

Scarring also becomes relevant if the device ever needs to be removed. When paddle leads are explanted, the scar tissue capsule that has formed around the base of the paddle must be carefully dissected. The lead is removed by gentle traction, but if resistance is encountered, the surgeon needs to verify that the base is fully freed from scar before pulling, to avoid tearing surrounding tissue or damaging the dura.¹⁵ Percutaneous cylindrical leads can usually be removed more easily due to their smaller profile, though long-dwelling leads may still require careful dissection.

Patients With Prior Spinal Surgery

Many candidates for spinal cord stimulation have already had one or more spine surgeries, often the very surgeries that left them with chronic pain. This prior surgical history can change the anatomy the implanting surgeon encounters. Scar tissue from a previous laminectomy may partially obliterate the epidural space, making it harder to thread a percutaneous lead smoothly or to position a paddle at the desired level. Hardware from a prior fusion, such as rods and screws, can physically block the path or distort the usual landmarks.

In patients with a spinal cord lesion (from injury or disease), the lead placement strategy may diverge from the standard approach. Rather than always placing the electrode at the level of the lesion, the surgeon may target segments above or below it based on where the pain is felt and whether the damaged cord can respond to stimulation at all.³ Pre-existing instability at the implant site has also been raised as a concern, since the added mechanical presence of a lead in a spine that already moves abnormally could contribute to repetitive local trauma and scarring over time.¹⁴

How Placement Verification Works During Surgery

Getting the lead to the right spot is only half the challenge. Confirming it is in the right spot is the other half, and the two main lead types handle this very differently.

With percutaneous leads placed under local anesthesia, the surgeon relies on fluoroscopy to visualize the lead’s position against the vertebral landmarks, then uses paresthesia mapping to verify functional coverage. The patient describes where they feel stimulation-induced tingling, and the surgeon adjusts the lead until the tingling overlaps with the pain area. In one study, one lead was placed using this paresthesia-based mapping technique while a second lead was placed purely by anatomical landmark at T9/T10, allowing researchers to compare the two approaches head to head.⁴

Surgical paddle leads placed under general anesthesia cannot use paresthesia feedback because the patient is unconscious. Surgeons rely entirely on anatomical knowledge, pre-operative imaging, and intraoperative fluoroscopy. Some centers use neurophysiological monitoring (recording electrical signals from the spinal cord during the procedure) as a partial substitute, but the lack of real-time patient feedback is a genuine disadvantage of the surgical approach.⁵ This tradeoff is one reason the choice between percutaneous and paddle leads is not straightforward. Paddles offer broader coverage and better positional stability, but percutaneous leads offer the advantage of awake placement with real feedback.

Living With an Implanted Device

After permanent implantation, the leads remain in the epidural space indefinitely, and the generator stays in its pocket until the battery runs out (rechargeable units last about a decade; non-rechargeable ones typically last three to five years, depending on usage). Generator replacement is a relatively minor outpatient procedure that only involves the pocket site, not the spine. The leads are usually left untouched unless they have migrated or malfunctioned.

Daily life with a stimulator involves some awareness of the hardware. You can usually feel the generator under your skin, especially if you are lean. Bending, twisting, and lifting can sometimes cause a brief change in stimulation intensity as the lead shifts slightly relative to the cord. Most patients adapt to these fluctuations within weeks. MRI compatibility is an important consideration and varies by device model. Some newer systems are labeled as MRI-conditional, meaning scans can be done under specific conditions (limited body regions, specific field strengths, certain scanning protocols). Older systems may be MRI-incompatible entirely, which can be a significant limitation if you need imaging for other health issues later on. This is worth discussing before implantation, especially if you have other conditions that are routinely monitored with MRI.

Activity restrictions in the first several weeks after implantation are common. Most surgeons ask patients to avoid raising their arms above their head, bending at the waist excessively, or twisting the torso for four to eight weeks. The goal is to let scar tissue form around the lead anchor, stabilizing it before the body starts moving normally again. After that healing window, most patients can return to regular activities, though high-impact sports and heavy lifting may remain a conversation with your care team.

1
PubMed. Spinal cord stimulators: typical positioning and postsurgical complications
2
Neuromodulation. A Visual and Narrative Timeline Review of Spinal Cord Stimulation Technology and US Food and Drug Administration Milestones
3
PubMed Central. Comparative outcomes of spinal cord stimulation for neuropathic pain: peripheral nerve versus spinal cord lesions
4
Neuromodulation: Technology at the Neural Interface. Comparison of Paresthesia Mapping With Anatomic Placement in Burst Spinal Cord Stimulation: Long-Term Results of the Prospective, Multicenter, Randomized, Double-Blind, Crossover CRISP Study
5
PubMed Central. Comparison Between Surgical and Percutaneous Paddles in Spinal Cord Stimulation for Chronic Neuropathic Pain
6
PubMed Central. Placement of spinal cord stimulation paddle leads in the thoracic spine using en bloc laminoplasty: A technical note
7
PubMed. Pocket pain, does location matter: a single-centre retrospective study of patients implanted with a spinal cord stimulator
8
PubMed. Is Pocket Pain Still a Major Issue in Spinal Cord Stimulation?
9
PubMed. A Temporary vs. Permanent Anchored Percutaneous Lead Trial of Spinal Cord Stimulation: A Comparison of Patient Outcomes and Adverse Events
10
PubMed Central. Migration of Epidural Leads During Spinal Cord Stimulator Trials
11
PubMed Central. Mitigating Spinal Cord Stimulator Lead Migration Complications in Minimally Invasive Spine Surgery: Technical Note
12
Neuromodulation: Technology at the Neural Interface. Peripheral Nerve Stimulation Relevant Anatomy, Morphology, and Implantation Techniques of the Dorsal Root Ganglia at the Lumbar Levels
13
PubMed. A paramedian approach for dorsal root ganglion stimulation placement developed to limit lead migration and fracture
14
PubMed Central. A Late Complication Related to Percutaneous Implantable Leads for Spinal Cord Stimulation: Myelopathy due to Fibrous Scar Tissue
15
World Neurosurgery: X. Safe explantation of spinal cord stimulator paddle electrodes