Trial of Continuous Versus Cyclic Stimulation in Interstim Therapy

Sacral Nerve Stimulation (SNS) delivers non-painful, mild electrical pulses to the sacral nerves to modulate the reflexes that influence the bladder, sphincter, and pelvic floor to improve or restore normal voiding function. Sacral nerve stimulation is indicated for refractory voiding dysfunction including urinary urgency/frequency, urinary urge incontinence, and nonobstructive urinary retention. Since its introduction, SNS has undergone significant improvements in design and application so that implantation is now a minimally invasive procedure under local and intravenous (IV) sedation. However, despite the progress made in advancing this therapy to a minimally invasive procedure, there are neither data nor guidelines on ideal program settings. The purpose of this study is to evaluate the programming parameter of cyclic versus continuous stimulation on efficacy of the therapy. If the therapy is equally efficacious at both settings, the cyclic setting has the advantage of resulting in a longer battery life.

The components of SNS include a quadripolar lead wire that is placed adjacent to a sacral nerve root (typically S3), and an implantable pulse generator (IPG) that the lead wire is attached to. The IPG provides the electrical impulse and has several parameters that are amenable to adjustment including rate, strength and length of stimulation. Additionally, the stimulation can be programmed to be continuous or cyclic. If the therapy is equally efficacious at both settings, the cyclic setting has the advantage of resulting in a longer battery life. This would prolong the time interval between IPG replacements which would reduce the number of times a patient is exposed to a surgical procedure and may have a substantial impact on reducing cost to the healthcare system. Participants will be randomized into one of two groups: either cyclic stimulation or continuous stimulation after IPG placement and will continue with this setting for four weeks. Subjects will return to the office 4 weeks post-op. They will complete a 3-day consecutive voiding diary just prior to their study visit. The subject will then undergo reprogramming to change the stimulation to the alternate pattern (from cyclic to continuous or vice versa as appropriate) keeping all other parameters the same. Subjects will be asked to return to the office 4 weeks after being switched to the alternate setting. She will complete a 3-day consecutive voiding diary just prior to the visit. The subject will also be asked their preference of mode of stimulation and the reason for their choice. After this visit, the participant will be switched to the mode of stimulation that is most efficacious for her.

Inclusion Criteria: You are eligible to participate in this study if you have the diagnosis of urge/frequency or urge incontinence and have undergone a successful Interstim trial and are planning on proceeding with IPG placement. All subjects must have had a minimum of a 50% improvement of one or more of the parameters being measured on the voiding diary to be considered a candidate for implant. Eligibility criteria also include non-pregnant women over the age of 18 who are able to provide informed consent and are willing to accept randomization. Exclusion Criteria: You are not eligible to participate in this study if: you are under 18 years of age; pregnant or planning to become pregnant; have underlying neurological disease; stress incontinence; unable to read English; inability to complete the voiding diary; and inability to complete the follow-up visits.