Pudendal Nerve Mapping Towards Improved Neuromodulation for Urinary Retention

Study Overview
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Brief Summary
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This study is to map the pudendal nerve. In this study the researchers will examine subjects who are already receiving an implanted stimulator at their pudendal nerve as part of their normal clinical care.

Detailed Description
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The pudendal nerve goes to the urethra, anus, and other areas of the pelvic floor. Electrical stimulation of this nerve can help with bladder problems and pelvic pain. Researchers do not understand how the nerve anatomy is different between people. Successfully mapping the pudendal nerve may help improve the medical care for future patients with bladder problems, pelvic pain, bowel problems, and sexual problems.

Official Title
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Pudendal Nerve Mapping Towards Improved Neuromodulation for Urinary Retention

Conditions
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Urinary Retention, Underactive Bladder

Intervention / Treatment
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* Device: Medtronic Interstim II Model 3058 Neurostimulator


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Clinically referred as having bladder problems that have not responded to conservative treatment. Normal clinical care includes referral to implant of Medtronic Interstim neurostimulator at the pudendal nerve. Fully eligible to receive an Interstim implant. Adult (18 or older), capable of providing own informed consent and communicating clearly with research team Capable of speaking, reading, and understanding English, as all study questionnaires are standardized assessments only available in English Capable of attending all experimental sessions (Visit 1: pre-stage-1 imaging, Visit 2: stage-1 surgery, Visit 3: CT after stage-2 surgery, Visit 3: cystometrogram test) Exclusion Implanted materials that prohibit magnetic imaging Any medical problems that prevent an individual from laying flat in an MRI or CT scanner, are are claustrophobic. Areflexive or atonic bladder Pregnant or planning to become pregnant. If a woman of child-bearing potential wishes to participate in this study, they will be pre-screened with a test to detect pregnancy. Diagnosed neurogenic bladder, pudendal nerve damage, lower motor dysfunction, or other conditions that would affect the neural circuits involved in micturition. Unwilling to allow de-identified data to be stored for future use or shared with other researchers.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Medtronic Interstim II Model 3058 Neurostimulator<br> | Device: Medtronic Interstim II Model 3058 Neurostimulator<br>* All stimulation parameters used will be within the normal hard-coded limits of the implantable pulse generator (IPG).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evoked bladder contractions of at least 20 centimeters of water (cmH2O) during the stage-4 test | At least 50% of participants | Visit 4, approximately 10 weeks after consent | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Selectivity index for selective stimulation of pudendal nerve branches for patient stimulation | Selectivity Index (SI) will be calculated for each sensor recording from distal pudendal nerve branches. This includes sensors in the proximal urethra (proximal perineal branch - PPB), distal urethra (distal perineal branch - DPB), and anal electromyography (EMG) (ischeal rectal nerve - IRN). The SI calculation may be modified in some patients, as necessary, for factors such as the presence of a short urethra that only allows for a single intraurethral pressure measure (female urethras < male urethras) and/or the placement of EMG in the perineal floor between yields one or more additional sensors. | Visit 2: Stage-1 (approximately 3 weeks after consent) | 
| Selectivity index for selective stimulation of pudendal nerve branches for simulated model stimulation | Selectivity Index (SI) will be calculated for each sensor recording from distal pudendal nerve branches. This includes sensors in the proximal urethra (proximal perineal branch - PPB), distal urethra (distal perineal branch - DPB), and anal EMG (ischeal rectal nerve - IRN). The SI calculation may be modified in some patients, as necessary, for factors such as the presence of a short urethra that only allows for a single intraurethral pressure measure (female urethras < male urethras) and/or the placement of EMG in the perineal floor between yields one or more additional sensors. | Visit 2: Stage-1 (approximately 3 weeks after consent) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pudendal nerve mapping