Standardized fluoroscopy-guided implantation technique enables optimal electrode placement in sacral neuromodulation: a cadaver study

Abstract

Background Sacral neuromodulation (SNM) is an established treatment option for patients with faecal incontinence. The location of the stimulating electrode is considered to be essential for treatment success. The purpose of this study was to evaluate the position of SNM electrodes after using a standardized fluoroscopy-guided implantation technique. Methods For this cadaver study, SNM electrodes were implanted bilaterally in 5 lower body specimens. The lower edge of the sacroiliac joint and the medial edge of the sacral foramina were marked using fluoroscopy to draw an ‘H’ with the crossing points identifying S3. After electrode placement the pelvis was dissected to describe the exact position of the SNM electrodes. Results The electrodes were inserted at an angle with a median degree measure of 60° (range 50–65°) to the skin, with a median distance of 9 mm (range 0–13 mm) from the S3 marking. All electrodes entered the third sacral foramen. The median distance of the electrodes to the sacral nerve was 0 mm (range 0–3 mm) for the most proximal, 0.5 mm (range 0–5 mm) for the second, 2.25 mm (range 0–11 mm) for the third and 1.75 mm (range 0–16 mm) for the most distant electrode. There was neither a significant difference in the proximity of the electrodes to the nerve between the right and left side (proximal to distal electrode: p = 0.18, p = 0.16, p = 0.07, p = 0.07) nor between male and female cadavers (p = 0.25, p = 0.21, p = 0.66, p = 0.66). Conclusions A standardized fluoroscopy-guided implantation technique enables a close contact between electrode and nerve. This can potentially result in an improved clinical outcome.

Technical and functional outcome after sacral neuromodulation using the “H” technique

“…An "H" is drawn on the skin site, and the intersection points of the "H" are intended as entry sites [2]. The "H" technique promises a better neuromodulatory effect by ensuring a close proximity of the electrode leads to the targeted sacral root S3 as we demonstrated in a previous study [3].…”

Comparison of surgical techniques for optimal lead placement in sacral neuromodulation: a cadaver study

“…These specimens were categorized as group A, representing the conventional guided implantation group. The other five specimens (3 female, 2 male) (group B) underwent bilateral fluoroscopy-guided lead placement using the “H” technique as previously described by Müller et al [ 7 ]. The results of both implantation techniques were compared ( n = 20).…”

“…Several factors are considered to contribute to the functional outcome [ 4 , 5 ]. Fundamental to success is the electrode's localization and its proximity to the sacral nerve [ 7 ]. Notably, lead migration was observed in patients with deterioration of initial treatment response, supporting the importance of the exact position of the inserted electrode [ 8 ].To date, only a few cadaver studies have evaluated anatomic landmarks for S3 localization and lead placement [ 9 , 10 ].…”

“…This standardized technique comprises fluoroscopy-guided marking of S3 by localizing the medial edges of the neural foramina and the inferior end of the sacroiliac joint [ 13 ]. In our recent cadaver study, Müller et al found that this technique led to a close median distance of the electrodes to the nerve [ 7 ]. This technique may result in an improved functional outcome and a higher rate of definite implants.…”

Sacral neuromodulation for faecal incontinence using the new Interstim™ Micro System — A stepwise teaching video

“…Sacral neuromodulation is an established treatment modality for patients with severe FI [4]. To optimize the functional outcome, close proximity of the lead to the sacral nerves is considered essential [9]. Thus, recently, a new 'H' implantation technique was introduced to achieve further improvement [10].…”