Urology Video Journal (Jun 2023)
Basic evaluation for sacroneuromodulation with the novel use of an in-line camera to guide lead insertion
Abstract
Background: Sacroneuromodulation (SNM) is a technique that simulates sacral spinal nerve roots with the goal of modulating afferent neural pathways. While the exact mechanism of effect is incompletely understood, it is an effective treatment in several pelvic floor disorders including Overactive Bladder (OAB), voiding dysfunction and non-obstructive urinary retention. The placement of SNM leads is guided by fluoroscopy or anatomical landmarks. The preferred target is the S3 sacral nerve. Correct placement is confirmed through obtaining the desired motor responses of anal bellows and toe dorsiflexion. Objective: To demonstrate our operative technique for SNM lead placement, including theatre set-up, use of fluoroscopy, identification of relevant anatomical landmarks and the novel use of an in-line camera to guide lead placement. Additionally, we demonstrate the motor findings associated with the target S3, and inadvertent S2 nerve stimulation. Patient and Surgical Procedure: We routinely perform basic evaluation trials for confirmation of symptomatic improvement (50% or greater), prior to single stage system implantation. We utilise the Medtronic Interstim device (Minneapolis, MN). Fluoroscopy and an additional in-line camera are used to guide all lead insertions. Confirmation of correct lead placement is achieved through visualisation of the desired motor responses. Additionally, stimulus amplitudes of less than 2 Vs are desired. Results: The use of an in-line camera acts as an additional reference point, allowing the operator to maintain an optimal craniocaudal angle during needle insertion. This is particularly useful in patients with a high BMI, where operator vision is limited, and early in the learning curve for trainees. Motor findings associated with both inadvertent S2, and the target S3 nerve stimulation are also demonstrated in a real-time case. Conclusion: Fluoroscopy and the use of an in-line camera allows for efficient SNM lead placement into the S3 sacral foramen.
