Bladder pain syndrome (BPS) has no known single aetiology, involving complex mechanisms of neuroplasticity and neuropathic pain. In this setting, sacral neuromodulation (SNM) is a possible treatment option after conservative measures and pharmacotherapy have failed. If successful, SNM is able to delay or even surpass the necessity for more invasive treatments. 
This study aims to demonstrate how augmentation cystoplasty after neuromodulation is a valid option, in a specific patient phenotype, exploring this evolving scientific area.

We conducted a secondary analysis of patients included prospectively in the Department Database. The two patients presented had their phenotyping of pelvic pain accordingly to the UPOINT classification, the severity of pain assessed with a visual score and were evaluated using the Interstitial Cystitis Symptom Index (ICSI). In the diagnostic assessment, the voiding diary and the urodynamic evaluation were also performed.

The patients, aged 58 and 64 years, experienced suprapubic pain associated with micturition for more than a decade.
The bladder diary demonstrated an increased urinary frequency (>15/day) and nocturia (10/night). No significant post void residual in both cases. Urodynamic evaluation revealed an intense bladder oversensitivity, accounting for a low functional capacity (under 200mL) and detrusor underactivity. A stepwise approach was offered, beginning with conservative therapies and oral medication, both ineffective. Hydrodistension was performed in one patient and the other underwent specialized physical therapy both with minimal clinical benefit. SNM was then performed with an improvement on their pain and quality of life, although frequent reprogramming of the device was required. However, after 4-5 years the effect diminished and the severity of the pain warranted the need for additional surgical treatment - an augmentation cystoplasty was then performed.
Following surgery, both patients demonstrated significant clinical improvement. Pain levels decreased from 10/10 to 5/10, and ICSI scores were markedly reduced—from 36 to 13 after 5 months in one patient, and from 36 to 18 after 2 months in the other. In addition, the spontaneously voided volume increased, exceeding 200 mL in both cases.

The UPOINT classification enabled us to phenotype these patients’ pelvic pain within the urinary domain. Urodynamic evaluation demonstrated low functional capacity and bladder oversensitivity, as expected in BPS. The reproduction of pain on bladder filling further supported the diagnosis. The sequential therapeutic options were applied as per guidelines, beginning with physical therapy and pharmacotherapy (gabapentin, pentosan polysulfate and oral analgesics) which were not successful. SNM is not formally approved for the treatment of BPS. Nonetheless, results in this area are encouraging, possible due to the effects on pain gate regulation at higher spinal segment levels, being considered a potential fourth line treatment. Our patients experienced reduced pain levels and achieved meaningful control of their symptoms for about 4-5 years. 
Neuromodulation may help defer or even obviate the need for major surgical procedures in this patient population. Unfortunately, the efficacy of SNM slowly decreased, while quality of life progressively worsened, prompting the need for a more definite solution, as an augmentation cystoplasty. The patients presented here are an example of success, with much less symptomatic burden at the moment and the ability to void with a much lower frequency.

SNM has the ability to alleviate symptoms of BPS, often reducing the need for more invasive treatments, especially when combined with other conservative and pharmacological therapies. However, some patients present unsatisfactory results or experience relapse after an initial good response. In such cases, augmentation cystoplasty may be an option for low volume bladders, providing increased capacity and lower storage pressures, potentially leading to significant improvement in symptomatic burden and quality of life.

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