EP341 - Removal of sacral nerve stimulators: A single center, retrospective review of 8 years. How does our experience compare?

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Purpose/Background: Sacral nerve stimulator (SNS) was first FDA-approved for urinary incontinence in the US in 1997 and subsequently for fecal incontinence in 2011. Early studies for SNS use in fecal incontinence found an infection rate of 10% and a reoperation rate of 24%, whether for device removal due to infection, electrode repositioning, chronic pain, or ineffectiveness. This review focuses on a single group of colorectal surgeons and the indications for SNS removal over the last 8 years, including the timing for removal.

Methods/Interventions: This was a retrospective study using chart review. Data was collected from a single hospital, and patients’ charts were reviewed using CPT codes to identify which patients underwent SNS placement and removal by two surgeons. All patients underwent SNS placement for fecal incontinence as the primary indication. Patients with an SNS permanently removed were identified, and their charts were reviewed including ICD 10 code/diagnosis and culture data when relevant. The timing between SNS placement and removal was determined for each patient.

Results/Outcomes: Since 2016, primary SNS placement has been performed on 86 patients. Of those 86, 15 patients required complete removal of their SNS device, totaling 17%. This did not include additional procedures such as battery exchange, device repositioning, or electrode adjustments. The following indications for removal included requiring an MRI for 6/15, intractable leg pain for 4/15, ineffective device and desired removal for 2/15, infection for 2/15, and non-compliance with incision care leading to wound dehiscence for 1/15. The timing for when the SNS was removed was noted for each case. The average time between insertion and removal was 16 months for pain, less than 2 months for infection, and less than 1 month for the non-compliant patient. For completeness's sake, the average time between insertion and removal was 34 months for an ineffective SNS and 22 months for an MRI requirement.

Conclusion/Discussion: Initial studies showed the infection rate of the SNS device to be 10% with our institution finding a much lower rate at 2.3%. Of those two patients, one was an infection after repositioning the device. This is consistent with other data for smaller studies. This may be due to regional or technical differences as this is a single-center study, though it is likely that initial studies overestimated infection rates. Notably, for patients who underwent SNS removal for pain, the average duration of time was 16 months after initial placement. This delayed pain development could be due to lead migration. Though this is a small study, it raises concern for studies with short interval follow-ups, often less than a year, which may have patients who developed neuralgia who were not captured. This was the second most common indication for device removal in our review.
As of 2020, with MRI-compatible leads being placed, we can expect a significant improvement in the SNS retention rate as 40% of the devices removed were due MRI requirements. Larger, multi-center reviews in the future may show 90% retention rate of SNS devices over 2 years. This review reinforces the durability of SNS for fecal incontinence finding that only 17% of our devices required removal, and one can expect that number to continue to improve.