An interventional study of Repetitive Transcranial Magnetic Stimulation (rTMS) and Sham Repetitive Transcranial Magnetic Stimulation (Sham-rTMS) in Interstitial Cystitis and Bladder Pain Syndrome, sponsored by University of Southern California. Active, not recruiting at 1 site in United States. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-17.
Sponsored by University of Southern California · Not applicable, Interventional, and Treatment
Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a common, chronic, and debilitating condition in women. Preliminary evidence suggests that IC/BPS pain can be reduced applying non-invasive repetitive transcranial magnetic stimulation (rTMS) to areas of the brain that regulate pelvic floor muscle activity. However, prior studies have examined rTMS in a very limited sample and have not examined changes in brain or pelvic floor muscle activity to determine the mechanism of rTMS for IC/BPS. This study is designed to directly address these limitations.
Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a common, chronic, and debilitating condition in women. The underlying cause of IC/BPS remains unknown. We recently published the first functional magnetic resonance imaging (fMRI) study comparing brain function in women with IC/BPS to healthy women. We found that women with IC/BPS have altered resting activity in supplementary motor area (SMA). Specifically, these changes appear in a part of SMA that we have shown to control pelvic floor muscle activity. We call this part of SMA "pelvic-SMA". Our results provide the first potential explanation for extensive published reports of increased pelvic floor muscle activity in women with IC/BPS. We hypothesize that we are observing evidence of an important theory of chronic pain: motor cortical changes occur that are initially beneficial to increase protective muscle activity but are ultimately maladaptive and perpetuate pain. If this theory is true, it should be possible to reduce pain and muscle activity by improving brain activity. The proposed work is to do exactly that. Using non-invasive repetitive transcranial magnetic stimulation (rTMS) directed at pelvic-SMA, we aim to determine if we can reduce pain (Aim 1), improve resting brain activity (fMRI) and resting pelvic floor muscle electromyographic (EMG) activity in IC/BPS (Aim 2), and to link the pain reductions to fMRI/EMG improvements to develop a causal mediation model of IC/BPS symptoms (Aim 3). We will recruit 50 women with IC/BPS to participate in the study, and participants will be randomized to 2 groups of 25: high-frequency (active) or sham (inert). Our preliminary data suggest that high-frequency stimulation is the best stimulation protocol for reducing pain and improving pelvic-SMA activity and resting pelvic floor muscle activity. Our preliminary results agree with a large body of literature suggesting that high-frequency rTMS applied to motor cortex is the best stimulus paradigm to reduce pain, but our proposed work has the potential to greatly innovate the field of non-invasive brain stimulation for pain by providing a mechanism by which the stimulation can improve deficiencies in motor function in chronic pain patients.
Exclusion Criteria:
Intensity: rTMS treatment intensity determined using resting motor threshold (RMT). Treatment will be delivered at 80% of the RMT. Site of Stimulation: Region of supplementary motor area (SMA) that regulates pelvic floor muscle activity. This target is defined in Montreal Neurological Institute (MNI) Coordinates of X=-2, Y=-16, and Z=68 mm. Frequency: 10 Hz. Duration: 20 Trains, 10 second duration, 50 second inter-train interval. Total number of pulses per session: 2000. Total number of session: 5 (one session per day for 5 consecutive days).
Device: Repetitive Transcranial Magnetic Stimulation (rTMS)
Identical to the High-frequency rTMS arm except delivered with an inert "sham" stimulation coil.
Device: Sham Repetitive Transcranial Magnetic Stimulation (Sham-rTMS)
Non-invasive magnetic stimulation of the brain
Device that appears identical to the active rTMS device, but does not produce any magnetic field and does not stimulate the brain.
Longer-term Pain
Change in Visual Analog Scale of Pain. This scale ranges from 0 (no pain) to 10 (worst pain imaginable), so higher scores indicate more pain.
Time frame: Before first treatment to 3 weeks after last treatment
Shorter-term Pain
Change in Visual Analog Scale of Pain. This scale ranges from 0 (no pain) to 10 (worst pain imaginable), so higher scores indicate more pain.
Time frame: Before first treatment to 1 day later just before second treatment
Global Response Assessment
Global Response Assessment (GRA)
Time frame: 3 weeks after last treatment
fALFF in Pelvic-SMA
Change in fractional amplitude of low-frequency fluctuations (fALFF) derived from functional magnetic resonance imaging (fMRI) in targeted region of the brain (pelvic-SMA)
Time frame: One hour before and one hour after first treatment
Pelvic floor muscle activity
Change in activity of pelvic floor muscles as measured by electromyography (EMG). EMG is a physiological parameter measuring the electrical potential generated by a muscle, indicative of its activity. EMG is measured in micro-volts and then converted to percent change.
Time frame: Just before to between five and ten minutes after start of first treatment
Plan to share: No
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University of Southern California