Sacral Nerve Stimulator Placement: A Novel Surgical Navigation Tool for...

Sacral neuromodulation delivers electrical impulses through a probe placed near the sacral nerve to improve quality of life in patients with constipation and fecal incontinence

Sacral neuromodulation technology acts like a pacemaker to promote bowel and sphincter function

Placement at this institution occurs in a hybrid operating room equipped with C-arm cone beam CT and surgical navigation system

The navigation technique enables offering this therapy to patients with dysplastic or malformed sacra whose anatomy would be prohibitive for traditional or purely fluoroscopic interventions

The horizontal axis for anatomical landmarks is marked at the posterior inferior iliac spine in the cranial aspect of the sciatic notch

The vertical axis is traced overlying the medial aspect of the S3 neural foramina bilaterally, roughly 2 centimeters from the midline

Conventional skin entry points are marked 2 centimeters cranially to the intersections of horizontal and vertical axes

Traditional approach without navigation provides access to the S3 foramina at a 60 degree angle

A cone beam CT run is acquired intraoperatively and a three dimensional model constructed for procedural guidance

With navigation guidance, the planned needle entry site was identified around 1 centimeter caudal to the traditional markings in this case

Proximity to the sacral nerve is assessed through electrical stimulation, with bellows contraction identifying proper placement at the S3 foramen

Plantar flexion of the great toe provides confirmation of proper S3 foramen placement

The neuromodulation lead is inserted using standard Seldinger technique with the dilator sheath provided

The marker should be visible halfway through the foramen on imaging

The tined lead is inserted under live visualization until the 3rd and 4th marks straddle the interior edge of the sacrum

The lead consists of 4 distal electrodes, tines or barbs for stabilization, distance markers, and 4 proximal connectors

A pocket is developed over the contralateral gluteus to accommodate the remaining lead, which is where the generator is to be implanted after the initial test period

The lead extension is attached and screwed in tightly until clicks are heard

Over the next 2 to 4 weeks, the patient's bowel function is carefully recorded and compared to previous records

If a positive effect is demonstrated with neuromodulation, a permanent generator is implanted in a second stage

If unsuccessful, the lead can be removed without permanent damage to the nerve