Patient Reported Outcomes Due to Bladder Neck Obstruction in Women Treated With Botulinum Toxin A Injection

Primary bladder neck obstruction (BNO) occurs when the bladder neck fails to open during voiding, causing urinary symptoms despite no anatomic obstruction. The cause of BNO is unclear but may involve neurogenic dysregulation related to the sympathic nervous system such as upper motor neuron lesion or peripheral autonomic neuropathy (small fiber neuropathy (SFN)). Another etiology can incuded increased sympathetic tone secondary to anxiety or stress conditons. Botulinum toxin A (BoNT-A) to the bladder neck has been used in our practice to treat women with BNO who failed conventional therapies (alpha blockers, relaxation strategies). This is the first report of patient-reported outcomes after BoNT-A treatment in women with pelvic pain and BNO.

We included female patients with pelvic pain and BNO who received BoNT-A to the bladder neck between January 2022 and March 2023, and mailed self-reported outcome questionnaires. The primary outcome was the Global Response Assessment (GRA); secondary outcomes included pain scores on the Visual Analogue Scale (VAS) and symptom checklists. BNO was diagnosed using Nitti Criteria (high bladder pressure, low flow in bladder neck on video urodynamics), supplemented by additional criteria (e.g., high voiding pressure, prolonged attempts, Valsalva effort, and cystoscopic evidence or symptoms related to BNO). Urodynamic studies followed International Continence Society standards. Additionally, due to BNO's association with SFN, patient history of biopsy-confirmed SFN was recorded.

Our inclusion criteria was satisfied among 18 patietns, with 17 completing the questionnaire. Out of those, 14 patients (77%) reported improvement on the GRA, with an average VAS of 8.3 ("Very Helpful"). The most commonly improved symptoms were feeling of incomplete emptying, difficulty starting stream, urethral burning, pain with urination, and pelvic pain. Postoperative symptom flares were reported in six patients for an average of 16 days. All six patients with biopsy-confirmed SFN showed significant improvement (VAS 8.7). Total of 14 patients (77%) indicated they would repeat the procedure.

BoNT-A to the bladder neck significantly improved pelvic pain and refractory hesitancy in women with bladder neck obstruction, especially in those with small fiber neuropathy. Symptom flares are common, but did not reduce interest in repeated treatments, and scheduling injections before symptom recurrence may mitigate these flares.