The prevalence of urinary lithiasis corresponds to 5% in the general population (1). Variations in urinary solute concentrations, urinary pH changes, functional and morphological changes in the urinary tract may increase the formation of stones (2).
Patients with neurogenic lower urinary tract dysfunction (ANLUTD) have a higher likelihood of presenting kidney stones, especially in the first year of diagnosis of neurological condition (1). Cohen et al. (3) described a risk of 60% in 5 years to develop urinary tract stones. The risk factors are immobilism causing hypercalciuria, inadequate bladder management, bladder augmentation surgery, indwelling bladder catheter, and non-continental urinary tract diversion (4).
Bladder stones (BS) are often associated with infravesical obstruction (4;5). However, the presence of ANLUTD should also be considered as a significant risk factor for the development (6). Few studies in the medical literature investigate the clinical characteristics correlated with the recurrence and even fewer studies comparing the different methods of treatment of BS.
This study aimed to compare open vs endoscopic surgery in a population of patients with a previous diagnosis of ANLUTD in a tertiary urological center, in addition to analyzing the clinical characteristics and studying the risk factors involved in new episodes of BS.

The present study comprises a retrospective study involving patients with clinical diagnosis of the ANLUTD who underwent elective procedures for treatment of BS in a tertiary university hospital from 2012 to 2022.
The information was collected directly from the medical records.
Patients were evaluated based on their epidemiological and clinical characteristics, including age, sex and presence of comorbidities.  The etiology of the ANLUTD was also evaluated and classified (Table 1). The procedures performed in patients (open or endoscopic surgery) were also analyzed, along with the time of operation, length of hospitalization, postoperative complications and registration of reinterventions that were necessary.
The choice between open or transurethral surgery was decided considering the measurements of BS and past abdominal surgery. Open surgery performed was cystolithotomy and transurethral cystolithotripsy was performed with Holmium YAG laser. After 6 months of follow-up, urinary US was performed and then the patients were followed up with annually.
The data collected in Excel® (Microsoft Corporation, Redmond, Wash.) and after input conferencing, the data were imported into SPSS® 27 for Mac (IBM, Armonk, New York) for statistical analysis. Continuous data were described by the mean and its respective standard deviation (SD) and 95% confidence interval (95% CI), and categorical data were described by absolute frequency and respective categorical proportion. Shapiro-Wilk test was used to determine if the data followed a normal distribution. If normality could not be assumed, Mann-Whitney U test was applied; otherwise, t-test was performed. 
The level of significance was set at p <0.05. Pearson's chi-square test was conducted to compare categorical variables, and Fisher's exact test was utilized instead when the expected frequencies were below 5.

Between January 2012 and November 2022, 73 patients underwent treatment with BS. In the follow-up, 84 procedures were performed with 42 (50%) open, 39 (46.4%) transurethral and 3 (3.6%) percutaneous, 53 men (72.6%) and 20 women (27.39%). The median age was 43 years (34.0 - 49.0). The etiology of the ANLUTD and the epidemiological and clinical profile of patients is shown in Table 1.
The mean follow-up was 71.30 months (range 124 - 7). The free rate of stones was 100% in the first 6 months post-operatory. Recurrence occurred in 11 cases, and the past of urinary tract surgery seems to be a major factor correlated with a new episode of BS (p=0.011; CI 1.21-82.34; HR:10.00). Classification B in ASIA score (p=0.019) and wheelchair use (p=010) were also associated with recurrence.
The median operative time was 75 min (IQR = 60 - 90), a median hospital stay of 2 days. Regarding preoperative urine culture, 15.2% of patients present Escherichia coli as a single germ, 4.5% Pseudomonas aeruginosa, 3% Klebsiella pneumoniae, 3% Enterococcus faecalis, and in 62.1% of cases 2 or more germs was founded in the same urine culture. 
Concerning the composition of the stones, Calcium phosphate was found in 27.38% (n=23), Struvite in 22.61% (n=19), Calcium oxalate in 21.42%  (n=18) and Calcium carbonate in 21.42% (n=18).
Initially, the two methods of treatment (open and endoscopic surgery) were compared. The difference between the medians of surgical times was statistically significant, being the fastest endoscopic method (p=0.048), however, the length of hospitalization (p=0.432), number and severity of postoperative complications (p=0.305), as well as the presence of recurrences (p=0.136) were not different between groups (Table 2).

In this study, we present a long-term follow-up of patients with ANLUTD and BS submitted to cystolithotomy and laser cystolithotripsy. Cystolithotripsy was performed in patients with smaller BS, being faster and with less recurrence in an unpaired analysis. After a paired analysis of common clinical and epidemiological factors, endoscopic cystolithotripsy may present fewer postoperative complications.
The prevalence of BS in patients with ANLUTD is estimated from 1.9% to 47% (3-7). Patients with ANLUTD have a higher risk of developing BS due to factors such as incomplete bladder emptying, urinary stasis and recurrent urinary tract infections. In our population, about 67% of patients had a history of recurrent urinary infection. In addition, measures to prevent the recurrence of BS and urinary tract infections, such as the use of clean intermittent catheterization (CIC) and behavioral interventions to promote bladder emptying, are essential for long-term management (11;12).
Our study presents a majority of patients with symptoms of BS as recurrent urinary infections (67.12%), followed by abdominal pain (28.4%) and hematuria (5.95%). A quarter of the patients present asymptomatic diverging from the presented literature. (16;17).
Bladder management is crucial to avoid BS formation. CIC is a common method of bladder management in patients with neurogenic bladder, and its use has been shown to reduce the risk of bladder stones. In a study by Sutherland and Lavers, patients who performed CIC were found to have a significantly lower incidence of BS compared to those who didn't (0.7% vs 16.9%) (18).
Open and transurethral surgery are two most common techniques for BS removal. Several studies have compared the outcomes of these two techniques and have found that transurethral surgery is associated with shorter hospital stays, less postoperative pain, and lower complication rates, that is similar to the results presented in this study.
Patients operated by open surgery in our study had a larger accumulated diameter. The faster time and the lower number of complications can also be explained by a selection bias, in which patients with more complex calculi end up being operated open and consequently have more complications and longer operative time.
The study is retrospective and cross-sectional, with limited statistical inference as to infer the superiority of one treatment method over another. In both methods patients were free of stones for at least 6 months, which denotes the efficiency of methods. This study emphasizes the importance of the correct choice of treatment according to mass of stones presented, past of urological surgeries and clinical conditions.

Bladder stone is a frequent complication in patients with ANLUTD diagnosis. It deserves attention in bladder management in order to avoid new episodes. Both open and endoscopic surgery are useful, however endoscopic surgery is associated with shorter hospital stays, less postoperative pain, and lower complication rates.

Ruffion, A., Traxer, O., & Chartier-Kastler, E. (2007). Lithiase et vessie neurogène [Stones and neurogenic bladder]. Progres en urologie : journal de l'Association francaise d'urologie et de la Societe francaise d'urologie, 17(3), 417–423. https://doi.org/10.1016/s1166-7087(07)92340-4
Chen, Y., DeVivo, M. J., & Roseman, J. M. (2000). Current trend and risk factors for kidney stones in persons with spinal cord injury: a longitudinal study. Spinal cord, 38(6), 346–353. https://doi.org/10.1038/sj.sc.3101008
Cohen, T. D., Streem, S. B., & Lammert, G. (1996). Long-term incidence and risks for recurrent stones following contemporary management of upper tract calculi in patients with a urinary diversion. The Journal of urology, 155(1), 62–65.