The purpose of this study is to evaluate if it is possible to use intravaginal high-density surface electromyography to guide Botulinum neurotoxin (BoNT) injection to treat pelvic floor muscle overactivity that complicates Chronic Pelvic Pain (CPP).

The management of pelvic floor overactivity (PFOA) using focal BoNT injection has been gaining clinical interest. Evidence has shown that BoNT injections to the levator ani in patients with CPP generated a greater than 50% improvement in symptoms at least 72% of the time, suggesting a promising efficacy of BoNT therapy. The current clinical standard for BoNT injection employs a fixed injection template or the manual palpation of a contracted muscle, followed by an injection towards the palpating finger. As such, the injection is highly subjective, operator-dependent, variable, and not tailored to individual patients, which may lead to inconsistent outcomes. Trigger point targeted injections have been practiced for many years worldwide, yet a recent randomized controlled trial reported no significant difference in outcome between trigger point targeted BoNT injections versus a saline placebo. Furthermore, it has also been reported that neuromuscular junction (NMJ) and trigger points are distributed in well-defined separate areas with a distance of approximately 10 mm apart. It has also been shown that BoNT injections made 10 mm away from the NMJ can reduce the efficacy of BoNT by 46%. Therefore, injections targeted at the trigger point may, in turn, compromise therapeutic efficacy.

The rationale of this study is that BoNT acts at the NMJ, where the neuromuscular junctions are densely located. By specifying the muscle(s) responsible for the pelvic floor overactivity, and the offending NMJ using high density surface electromyography (HD-sEMG), BoNT can be injected with greater accuracy and objectivity to optimize treatment efficacy. The investigators aim to test the hypothesis that interstitial cystitis patients in the guided injection arm will demonstrate lower hypertonic metrics and improved quality of life. The purpose of this study is to provide preliminary evidence supporting the use of HD-sEMG and NMJ mapping to guide BoNT efficacy.

Inclusion Criteria:

• Inclusion criteria for interstitial cystitis/bladder pain syndrome (IC/BPS) patients will be:

  1. Woman aged 18 to 60.
  2. Have a clinical diagnosis of IC/BPS.
  3. Pain, pressure, or discomfort in the bladder and/or pelvic area for the past 6 months or more, associated with lower urinary tract symptoms (such as frequency of urination), in the absence of other explanation of the symptoms (e.g., urinary tract infection).
  4. Myofascial pain diagnosed with palpable contracted muscle fibers.
  5. Pelvic muscle tenderness by assessment of pelvic floor muscles on digital pelvic examination.
  6. Pelvic floor hypertonicity (PFH), measured using vaginal manometry (pressure > 35 cm∙H2O).
  7. Ability to provide informed consent.

Exclusion Criteria:

• Exclusion criteria consist of the following:

  1. History of pelvic malignancy and sexually transmitted diseases.
  2. Bleeding disorder such as coagulopathy
  3. History of neurological disorders, such as spinal cord injury, multiple sclerosis, amyotrophic lateral sclerosis or myasthenia gravis.
  4. Pregnancy, breast feeding or desiring for pregnancy in the coming year.
  5. Subjects with history of pelvic surgery (e.g., pain from mid-urethral sling or pelvic mesh),
  6. Pelvic malignancy (urinary tract, gynecologic, gastrointestinal)
  7. Active fistula
  8. Radiation cystitis
  9. Cyclophosphamide cystitis
  10. Pre-existing anorectal disorders
  11. Infections near the injection sites
  12. History of drug or alcohol abuse
  13. Hypersensitivity to BoNT
  14. Steroids or hormone usage will be carefully considered by the research team for inclusion.

Participants with on-going BoNT therapies will not be screened until the complete drug washout is confirmed.