Sacral Neuromodulation (SNM), FDA-approved in 1997 for adults with urge incontinence and later for overactive bladder (OAB) and nonobstructive urinary retention, has seen an increase in off-label use in children despite lacking FDA approval for those under 16, owing to positive outcomes.

While SNM has shown success rates of approximately 70–80% in randomized studies involving adults, there are unique considerations in pediatric populations that warrant further exploration, including long-term outcomes and potential mechanisms of action.

The mechanism, believed to stabilize neurological voiding mechanisms by stimulating afferent somatic sacral nerves, remains not fully understood.

Based on the review conducted, pediatric patients undergoing implantable sacral neuromodulation therapy for voiding dysfunction experienced a high rate of symptom improvement, with an overall improvement rate of 68%, and complete resolution of symptoms observed in 39% of cases. These improvements encompassed various urinary symptoms, including urinary incontinence, frequency, urgency, and nocturnal enuresis. Additionally, psychosocial and total quality of life scores improved significantly post-treatment, although physical quality of life scores did not show significant improvement.

Urodynamic improvements were also noted, with reductions in detrusor pressure, uninhibited detrusor contractions, and postvoid residual volume observed in several studies. SNM treatment also led to a decrease in the recurrence of urinary tract infections (UTIs) in some cases, and a significant proportion of patients managed to reduce or discontinue the use of bladder-related medications post-treatment.

However, it is crucial to acknowledge the complications associated with SNM therapy, such as lead issues, device migration or erosion, pain, and device removal due to inefficacy or infections. Notably, 25% of devices were permanently explanted due to inefficacy, and 4% were removed due to infections. This underscores the importance of careful patient selection and counseling regarding the potential risks and benefits of SNM therapy.

Furthermore, there is a paucity of studies addressing symptom resolution to facilitate device removal in BBD patients treated with SNM. Recently, Rensing et al. investigated SNM device survival in 67 pediatric patients over a median 2.2-year follow-up period, identifying a growing likelihood of explantation for symptom resolution, reaching up to 32% by the fourth year [1]. Patients explanted for symptom resolution showed improved symptoms and quality of life compared to those explanted due to complications, providing valuable insights into SNM outcomes in this demographic.

The higher rate of explantation for symptom resolution observed in pediatric patients compared to adults suggests a potentially greater responsiveness to SNM therapy in younger populations, possibly due to increased neuroplasticity of central and peripheral nervous systems. This leads to speculation on whether sustained effects observed from childhood interventions could modify or eliminate future adult LUTS if treatment begins during childhood.

Challenges with device placement in smaller-sized pediatric patients include technical difficulties in positioning the lead for effective stimulation, with lead breakage frequently reported in reviewed studies. Pellegrino et al. reported a reoperation rate approaching 100% in pediatric patients undergoing SNM, attributing it to factors such as battery replacement, implant migration during growth, and device removal [2]. Clark’s et al. small study found device malfunction in three pediatric patients associated with a mean somatic growth of 8.1 cm, leading to surgical revision and restored efficacy after revision [3].

Stephany et al. observed a higher rate of lead complications in patients with a lower body mass index (BMI), suggesting that the lack of adipose tissue protecting the lead could increase the risk of lead breakage [4]. Pain over the generator site was frequently reported as a cause of generator revision in reviewed studies, possibly due to insufficient adipose tissue cushioning.

Mason et al. proposed a low BMI as a predisposing factor for reoperation, citing the vulnerability of a thin layer of subcutaneous fat in protecting the neurostimulator and electrodes from damage during physical activity and frequent falls in young children compared with adolescents [5].

However, Fuchs et al. did not find a significant association between BMI and re-operative complications, necessitating further study [6].

Groen et al. reported a high reoperation rate, primarily due to lead dislocation and infection, with efforts recommended to enhance the tined lead for use in children. The infection rate was 13%, possibly related to an extended test period and a two-stage procedure [7]. Efforts should be made to minimize the interval to prevent infection.

A final concern regarding SNM use in children is the permanent placement of a device in patients who may outgrow their symptoms. Roth et al. offered patients with at least 12 months of symptom relief a trial of device deactivation; 10% did not experience a return of symptoms and subsequently had their devices explanted [8]. It remains unclear if this finding is related to the child outgrowing their symptoms or to imperfect patient selection.

Due to these challenges and concerns, patient selection in the pediatric population is crucial. A comprehensive medical history, physical examination, and relevant testing should be conducted to rule out correctable etiologies for the child’s symptoms. Extensive counseling for the child and family regarding the risks and benefits of the SNM procedure, particularly the potential need for reoperation as the risk increases with time, is imperative. This underscores the need for shared decision-making processes and informed consent, ensuring that families are well-aware of the potential benefits and risks associated with SNM therapy.

Limitations to this review include the challenge of population heterogeneity in these studies complicating direct comparisons. Variability in age, comorbidities, and the nature of voiding dysfunction adds complexity to the interpretation of results.

Additionally, the absence of standardized terminology, especially predating the International Children’s Continence Society (ICCS) standardization endorsing “bowel and bladder dysfunction” (BBD), hinders diagnosis consistency. This complexity introduces challenges in interpreting and generalizing results, especially for conditions like Overactive Bladder (OAB) and dysfunctional voiding.

Moreover, the use of diverse evaluation methods further complicates result interpretation. Some studies rely on subjective parameters like the Vancouver Non-neurogenic Lower Urinary Tract Dysfunction/Desire to Void questionnaire and the Pediatric Quality of Life Inventory (PedsQL) questionnaire, potentially introducing placebo effect bias. Others use more objective measures such as voiding diaries, ultrasound, uroflowmetry, or urodynamic studies.