Page 105 - Bladder Dysfunction in the Context of the Bladder-Brain Connection - Ilse Groenendijk.pdf
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                 Acute effect of sacral neuromodulation for treatment of detrusor overactivity on urodynamic parameters 103 INTRODUCTION
Overactive bladder (OAB) is a condition defined as urgency, with or without urgency urinary incontinence, usually associated with frequency and nocturia.1 The prevalence is described to be between 11 – 16% worldwide and is expected to increase as a result of the aging of the population causing a high burden on society.2,3 The pathophysiology of this highly prevalent disease is still being explored and the value of urodynamics (UDS) in OAB is investigated. About 54.2% of patients with symptoms of OAB show detrusor overactivity on UDS.4
Currently, first-line treatment consists of conservative treatments like pelvic floor muscle therapy (PFMT) and second-line treatment of oral anticholinergics or betami- metics. Neither of these treatments is very efficient. Research shows that the benefit of PFMT is not maintained on the long term and more than 50% stop anticholinergic drug treatment within the first three months because of lack of benefit and adverse effects.5
Sacral neuromodulation (SNM) is a safe and effective third line therapy for symp- toms of OAB.6 SNM is supposed to suppress involuntary bladder contractions and to normalize bladder sensation via afferent nerve modulation.7 Prior to implantation of a sacral neuromodulator, a percutaneous nerve evaluation (PNE) or first stage tined lead placement test (FSTLP) is done to evaluate the efficacy in the OAB patient. In patients with an improvement of ≥50% of symptoms, evaluated with bladder diaries, a sacral neuromodulator is implanted.5
Different properties of SNM in bladder dysfunction have been investigated; such as the onset of action, the wash-out period and the effectiveness of intermittent and on- demand SNM.8-11 An argument for intermittent or on-demand SNM was a longer battery life, and consequently fewer surgical replacements, although the need for intermittent SNM is less urgent since the introduction of the rechargeable battery.12 In some studies it was found that efficacy of SNM decreased after 5 years.13 Adaption by the nervous system was postulated as the cause of this.10,14 Other studies found that the therapeutic effect of SNM was stable after 5 to 6 years.6,15
Implantable ultrasound devices and potentiometers to detect bladder filling and contractions have been studied in pigs.16,17 Such devices could be helpful in the develop- ment of a feedback system in which the neuromodulator automatically activates when the detrusor pressure is increasing.18 If acute SNM has direct inhibitory effects on bladder function, such a closed-loop feedback system could be of potential value for patients with OAB. Studies in rats demonstrated an acute inhibitory effect of neuromodulation on bladder contractions.19
Whether UDS parameters can predict the success of SNM in patients has been inves- tigated, but no predictive UDS parameters have been found.20,21 Moreover, when com- paring UDS parameters before and during SNM (six months stimulation), several UDS
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