Hypothesis / aims of study
The objective is to analyze the characteristics of patients with LUTS secondary to Neurogenic Lower Urinary Tract Dysfunction (NLUTD) that have been treated with sacral neuromodulation (SNM), the results and long term complications of the technique.
Study design, materials and methods
This is an observational, descriptive, retrospective, single center study of patients with LUTS secondary to neurogenic bladder managed with sacral neuromodulation in our institution from 1998 to 2017.
Those patients with LUTS secondary to NLUTD and who do not respond to standard of care, SNM was offered in real life clinical practice. Every patient signed an informed consent.
Results
A total of 22 patients were included, 14 (63.6%) women and 8 (36.4%) men. Of them, 6 (27.4%) patients have arterial hypertension, 3 (13.6%) diabetes mellitus, 3 (13.6%) psychological disorders, 9 (40.9%) patients showed sexual dysfunction and 11(50%) neurogenic bowel. Table 1 shows disorders associated with NLUTD. The most frequent neurogenic disorder was incomplete spinal cord injury in 5 (22.7%) patients, myelitis in 4 (18.2%) patients, myelomeningocele in 3 (13.6%) patients, and others less frequently.
Mean age at implantation was 51 (± 16.2) years old. The mean time from diagnosis to implantation was 6.4 (± 4.5) years. Before implantation, the most frequent clinical diagnoses were urgency urinary incontinence (UUI) in 14 (63.6%) patients, voiding dysfunction 5 (22.7%) patients, urgency-frequency (UF) 2 (9.1%) patients and chronic urinary retention (UR) 1 (4.5%) patients. The most frequent urodynamic findings were detrusor overactivity in 8 (36.4%) patients, detrusor overactivity with urinary incontinence 4 (18.2%) patients, acontractile detrusor in 3 (13.6%), detrusor underactivity in 2 (9.1%) and other less frequently (table 1).
Before SNM, patients had tried a mean of 2.8 (1-9) treatments. All patients with bladder storage symptoms were treated with anticholinergic drugs alone or in combination, and 5 (22.7%) patients were treated with Onabotulinumtoxin A detrusor injections.
Tined Lead (two stage) technique was performed in 21 (95.4%) patients, and peripheral nerve evaluation with electrode implantation by open approach in 1 (4.6%) patient. In 19 (86.3%) cases the procedure was performed under local anesthesia, and general anesthesia was used in 2 (9.1%) procedures.
Success rate during temporary stimulation period was 59% (13 patients). All of them receive a definitive implant. Table 2 summarizes the success rate of test phase and permanent SMN at last follow-up.
Before temporary stimulation period, 9 (69.2%) patients suffered urinary incontinence. One month after definitive implantation it was reduced to 3 (33.3%) patients and to 1 (11.1%) patients at 12 moths after implantation. At 12 months the success rate in patients with urinary incontinence per-protocol and intention-to-treat was 88.9% and 57.1% respectively.
Before temporary stimulation period, only 2 (9.1%) patients suffered urgency-frequency (UF). Only one of them (50%) had positive response in the temporary stimulation and receive a definitive implant. This patient was asymptomatic at moth and at 12 months after implantation. Therefore, at 12 months the success rate in patients with UF per-protocol and intention-to-treat was 100% and 50% respectively.
At baseline 5 (38.5%) patients performed clean intermittent catheterization (CIC), with 4.6 catheterizations at day by mean. 12 months after definitive implantation it was reduced to 3 (60%) with 2.3 catheterizations at day by mean. At 12 months the success rate in patients with CIC per-protocol and intention-to-treat was 40% and 22.2% respectively, with a 50% reduction in number of catheterizations at day.
Mean follow-up was 52.6 (± 37.9) months (median 36 months). The average duration of the effect was 51.2 (± 39.4) months. 4 (30.8%) patients needed exchange of the battery at 43.8 (± 30.7) months by mean. Only 5 (38.5%) patients present some late complications. 1 patient (4.5%) presented high impedance, 1 patient (4.5%) presented implant extrusion, both treated by electrode replacement. 1 patient (4.5%) presented accommodation and underwent Onabotulinumtoxin A detrusor injections. 1 patient (4.5%) presented aversion to implant and it was removed. 1 patient (4.5%) suffered implant site pain requiring local corticosteroids injection. Re-operation rate was 23%. No patient presented implant infection.
Interpretation of results
SNM can have an inhibitory effect on neurogenic detrusor overactivity. While SNM has a place in the care of neurogenic urinary incontinence or chronic urinary retention, the proportion of patients improved seems to be lower than in non neurological patients according to literature. We observed a 55.6% success rate in UUI, 100% UF and 40% UR patients. The global success rate (improvement over 50%) was 84.6% per-protocol and 50% in intention-to-treat patients at 12 months follow up. Our figures are very similar to a systematic review on SNM for NLUTD 1. Main drawback of our study is the retrospective nature, and the small number of patients included. Keeping all these facts in mind, we think that SNM might be effective and safe, nevertheless, we only offer SNM to those patients with NLUTD who are refractory to standard of care.