Does sacral ratio have any impact on success rate of biofeedback therapy in children with lower urinary tract dysfunction?

INTRODUCTION: To evaluate the possible impact of patients' sacral ratios (SRs) on response to biofeedback (BF) therapy in pediatric patients with lower urinary tract dysfunction (LUTD).

MATERIALS AND METHODS: In this retrospective cohort conducted from 2016 to 2018 in our tertiary medical center, we included the medical records of all pediatric patients with LUTD who were nominated for BF due to having abnormal uroflowmetry patterns and simultaneous increase in electromyography (EMG) activity. Ten sessions of weekly animated BF were performed for each patient. All patients underwent a complete urological evaluation, uroflowmetry with simultaneous EMG and post-void residual measurement before and after treatment. SRs were calculated based on plain anteroposterior lumbosacral radiographs. Patients were then divided into normal SR (≥0.74) and low SR (<0.74) and outcomes were compared between them.

RESULTS: Of the total 86 patients included in our study, 48 (55.8%) had a normal SR (≥0.74), while 38 (44.2%) had a low SR (<0.74). Our data revealed that BF therapy significantly improved maximum and average urinary flow rates, urine volume, daytime urinary incontinence, enuresis, urinary urgency and constipation; irrespective of the patients' SRs (all P < 0.001). Our between-groups analyses showed that after the completion of BF, the SR ≥ 0.74 group had significantly higher maximum urinary flow rate (mean difference [95%CI]: 7.7 [5.4, 10.0], P < 0.001) (Figure) and urine volume (mean difference [95%CI]: 49.9 [19.5, 80.4], P = 0.002) and significantly lower diurnal urinary incontinence (4.2% vs. 21.1%, P = 0.020), enuresis (4.2% vs. 18.4%, P = 0.040) and constipation (2.1% vs. 23.7%, P = 0.004) compared to the SR < 0.74 group.

DISCUSSION: SR has been proposed as a reliable indicator of bony pelvis growth and subsequent lumbosacral neurodevelopment. Additionally, larger SR values are associated with better postoperative sphincter function in children with urological and anorectal malformations. Our results demonstrated that after completion of BF, the normal SR group had a significantly better improvement of some of the uroflowmetry indicators and LUTD-associated symptoms compared to the low SR group.

CONCLUSION: Our findings implied that although BF therapy is an efficient treatment for children with LUTD, irrespective of their sacral development; children with enhanced sacral development may benefit from better clinical response, especially in terms of LUTD-associated symptoms.