Hypothesis / aims of study
Up to now more than 400,000 patients have been implanted worldwide and sacral neuromodulation (SNM) has become an established minimally invasive therapy for refractory overactive bladder, non-obstructive urinary retention, and fecal incontinence. Experiences in pediatric population are limited and safety and effectiveness have not been established. In children urological treatment under the age of 16 yrs, for patients with neurological disease origins, or for bowel control under the age of 18, SNM is not approved . For these reasons ICCS and ICI reported a low level of recommendations, while an increasing pediatric studies reported improvement of bladder/bowel function in children. Different factors influenced on SNM outcome, where no specific factor, responsible for the success or failure of implanting, has been defined. For this reason hereby we present our results in 65 pediatric patients implanted, presenting our protocol for selection , implant and follow-up.
Study design, materials and methods
SNM has been considered in our Division a third line treatment. According to this statement a protocol has been defined and approved by our Hospital Scientific Committee in 2008. All patients have been evaluated and treated after a written consent has been signed and all other treatment failed. Considering the pediatric age all patients have been informed about the off-label condition for SNM. All patients have been treated according to a protocol: a ) preoperative, b) surgical, c) post-op and follow-up.
A)Preoperatively all patients performed: a new clinical evaluation , taking again patient’s history and physical examination,Urinalysis and blood exams, checking 48 hrs urinary and bowel diaries, sacrum X-ray, renal/bladder ultrasound , a no invasive urodynamic studies ( FLW,EMG, PVR if micturition present), UD+ VCUG or VUD, Neurophysiological test, Psychological evalution, QoL. Patients with renal function impairment or dilatation of urinary tract > 10 mm, or VUR or mental impairment have been excluded. In order to define clear outcome measures, we defined success when patients reported own satisfaction plus amelioration of 50% of one or more between : leaking episodes per day (number and degree), Number of pads/day , Post void residual decrease, N° of intermittent catheterisms per day,Episodes of faecal incontinence per day ,Number of defecation per day
B) Surgery: all patients have been treated with a 2 stage technique. Advanced test ( using quadripolar electrode instead PNE) has been used in all. Second stage, implant has been performed after a successful control period of 2-8 weeks, on the basis of clinical improvement, patient's satisfaction, excluding worsening of renal function and upper urinary tract. UD test have been reported but not considered as main outcome. During surgical procedure fluoroscopy control has been used in all. Choice between local or general anesthesia has been discussed with patients above 14 yrs old. All patients have been treated in inpatient regimen, with antibiotics treatment for 7 days in each procedure.
C) Control and follow-up have been performed regularly at 1,4,12,36, 52 weeks and then twice/year.
Patients with a minimum of 12 months follow-up have been included.
Results
72 patients between 2008-2021 have been operated, aged 11-19 yrs. 3 pts have been exclude because limited follow-up, < 6 months. 4 pts performed test , first stage, but non presented criteria for second stage.About 65 its, 39 presented neurogenic bladder dysfunction, 15 non neurogenic idiopathic urinary retention (NNIUR), 8 overactive bladder with urgency, frequency and urinary incontinence, 6 presented bowel dysfunction as main symptom, fecal incontinence. Implants have bene always performed in lee damaged neurological side, , prep evaluation, but 5. Overall success rate has been 70% at 12 months and 65% later, maintaining during time. Early surgical complications have been observed in 5, 1 intraoperative electrode breaking during removal, 4 infection, 2 electrode removal. All required reoperation, Later complications have been observed in 9 cases: electrode breaking during time in 5, battery dislocation in 5 , 4 of them followed by infection and skin erosion, with reimplant of new battery in contralateral side. Regarding neurogenic bladder dysfunction, overall success has been 65%, iatrogenic injury 80%, peripheral neuropathy 90%, myelomeningocele or lypomeningocele 0%, complete SCI 0%, occult spinal dysraphysm 50%. 15 pts removed device for resolution of symptoms.
Interpretation of results
According to our results a careful selection seems to be useful either for the choosing correct indication ( neurological lesion) either the side for implant. In our opinion some disease seems to offer best chance for positive response, as iatrogenic injury or peripheral lesion ( incomplete damage) versus others with complete damage ( SCI or MMC) all without response. Sharifiaghdas evaluated SNM’s effectiveness for managing refractory neuropathic lower urinary tract infection in children and adolescents: 61,53% of patients had positive test phase. Positive response was achieved in 85% at a mean follow-up of 14 months, and reported not difference in efficacy between patients with different pathologies.This data is contrasting with our experience. Complications rate seems high in our experience , where a younger age, as suggested seems to offer a better response, but presenting an highest complications rate due probably to height grow-up and variation in body mass index(BMI). In 2017 study identifying preoperative factors which associated with postoperative complications after SNM , others concluded, that there is no association between age, gender and BMI and postoperative complications. Regarding UD usefulness , Mason observed greater improvement in pts with uninhibited detrusor contractions. This is confirmed by our experience where underactive detrusor responding well too, where UD usefulness seems more relevant in preoperative period.
In 2021, Boswell reported the long-term results (2002-2019) of reoperation after SNM in one center. There were 154 total secondary surgeries in a 187 pediatric patients. There were 83 device revisions, with 89% of revisions for a non-functioning device, 8% for pain, and 2% for infection. In their cohort of children 68% carried a high reoperation rate. Critical point in our view are occult spinal disraphysm, where maybe different architectural configuration and ultrastructural properties of sacral plexus in these patients could justify discrepancies in results ( van Der Jagt 2012).
Concluding message
SNM activity in pediatric population is increasing during time, because reported effectiveness and MRI compatible device. Furthermore rechargable devices are now available. SNM in pediatric is presenting some critical points to be considered: a) patients selection ad role of Sacral abnormalities ( sacral roots and foramen) , b) Optimal age for implant ? ( early stimulation versus risk of dislocation and trauma in younger), c) to define common outcome measures, d) electric field parameters for neuromodulation ( Hz, V, used) that are scantly reported complicating evaluation of different series. According to 7th-ICI , SNM in pediatrics must be considered carefully because is Not approved in children, small study populations in different series with heterogenic pathologies but high complications rate. Good clinical response rate for neurogenic bladder and urinary functionally disorders are reported as well as seems to be effective in bowel bladder dysfunction, refractory constipation or faecal incontinence, but level of evidence remains low..
Cost effectiveness is debated, but is better considering in a 5 years period ( normal activity of no rechargable battery) and not for single surgical procedure versus onabotulinum toxin A ( less expensive but to repeat every 6-8 months). SNM in pediatrics must be used only in very few high level selected center, with a multidisciplinary team and high rate volume activity ( minimum of 5 implants/year).