in 2002 , overactive bladder syndrome ( oab ) was defined by the international continence society as " denoting urgency with or without urge incontinence , usually with frequency and nocturia in the absence of urinary infection or another identifiable disease " . the prevalence of this syndrome in adults varies between 12% and 17% and rises with age . in europe , the prevalence ranges from 12 to 22% , in the united states the prevalence is around 16% , and in spain it is 21% [ 2 - 4 ] . oab negatively impacts the patients ' quality of life , especially when they present with symptoms of bladder filling , such as micturitional urgency and its associated incontinence . treatment with anticholinergic drugs acting on the detrusor muscarinic receptors are , in most cases , the first - choice treatment for this type of patient , although a significant percentage of patients do not respond to this treatment owing either to lack of adherence or lack of efficacy or tolerability . when treatment with antimuscarinic drugs is not effective , other treatment alternatives include the following : conduction therapies , the use of drugs such as uroselective alpha - blockers , neuromodulation , intravesical botulinum toxin , and even posterior tibial nerve stimulation ( ptns ) . the purpose of our study was to assess in an objective way both the efficacy and the results of ptns in patients with oab in which treatment with anticholinergics ( antimuscarinics ) was not clinically effective . we designed a unique cohort study of 14 patients ( before and after study ) to assess the efficacy of treatment with ptns in patients with oab in which treatment with anticholinergics was not effective for 6 months previously . fourteen female patients were diagnosed with oab according to the definitions set out by the international continence society in 2002 . before stimulation , all patients had been treated with maximum - dose anticholinergics ( solifenacin or fesoterodine ) and presented with no clinical improvement according to their pre- and post - treatment micturitional diary in which diurnal micturitional frequency , nocturnal micturitional frequency , urgency episodes , and urge incontinence episodes were recorded and compared . after a minimum 2-month washout period after the oral anticholinergic treatment , the ptns treatment was started . the treatment protocol consisted of 14 sessions per patient conducted as follows : 8 weekly sessions , 4 sessions every 15 days , and 2 monthly sessions . before starting treatment , a urodynamic study was performed and a 48-hour micturitional calendar was provided to assess diurnal micturitional frequency , nocturnal micturitional frequency , urgency episodes , and urge incontinence episodes . after 14 ptns sessions , every patient turned in this 48-hour micturitional calendar in which the same aforementioned variables were assessed . we also assessed adherence to treatment , satisfaction or subjective feeling of improvement , and collateral side effects and complications of the treatment . we performed statistical study of the results by applying the wilcoxon test for nonparametric sample comparison , with statistical significance established as p0.05 . for the statistical analysis , we used spss ver . 17.0 ( spss inc . , the hospital ethics committee authorized the use of ptns in oab and approved this work . a total of 14 women diagnosed with oab with a mean age of 60.8 years were treated . every patient underwent 14 sessions of ptns , although two patients did not complete the treatment owing to a lack of subjective improvement . of the 14 patients included in this study , only 1 presented with oab with a known cause ( multiple sclerosis ) . we conducted urodynamic study in all the patients before starting the ptns treatment , and nine of the patients presented with detrusor hyperactivity waves . the 48-hour micturitional calendar provided by the patients before starting the ptns treatment showed the following means : diurnal micturitional frequency , 12.6 times ; nocturnal micturitional frequency , 3.1 times ; urgency episodes , 10.9 times ; and urge incontinence episodes , 5.2 times . at the completion of treatment ( 14 sessions ) , the patients were again requested to submit their 48-hour micturitional diary , which documented the following : diurnal micturitional frequency , 10.2 episodes ; nocturnal micturitional frequency , 2.7 episodes ; urgency , 6 episodes , and urge incontinence , 2.5 episodes ( fig . 1 ) . after applying the wilcoxon test for paired samples and analyzing these four variables , we observed statistically significant improvement in the diurnal micturitional frequency ( p=0.05 ) , urgency episodes ( p=0.003 ) , and urge incontinence episodes ( p=0.004 ) but no significant improvement in the nocturnal micturitional frequency ( p=0.472 ) ( table 1 ) . when we analyzed the patients ' subjective feelings of improvement regarding the treatment , we found that 50% reported improvement and another 50% reporting feeling no difference . when we compared this result with the anticholinergic treatment in these patients previously ( for which 100% of patients felt no subjective difference ) , the results were statistically significant ( p<0.05 ) . of the two patients who did not complete all 14 sessions , one showed improvement when we considered the micturitional calendar filled out after the 8th session ( the last one for this patient ) . the other patient did not show improvement after filling out the calendar at the 6th session , which was the last one applied . ten patients reported pain in the electrode application zone during the treatment that was not an obstacle to completing the treatment . no complications or side effects were reported after ptns in these 14 patients with oab . after a mean of 8.5 months of follow - up , the patients ' symptoms had stabilized and no progression of symptoms was shown . treatment of oab with anticholinergics ( antimuscarinic ) can have a lack of benefit in up to 60% of cases depending on the kind of patient and the sex of the patient . accordingly , many patients express a wish to change their treatment to another anticholinergic drug or another type of therapeutic . generally , the most common reasons for a change of the medication are a lack of therapeutic response , new medications , side effects , and the acceptance , by some patients , that their pathology is not going to improve no matter which treatment they receive . analyzing the symptoms experienced by these patients , which result in often drastic measures taken in an attempt to lead a relatively normal life , brings to light the enormity of the problems that arise from this syndrome and explains why these patients often demand a solution to their problem or feel there is unacceptable improvement of their symptoms with the prescribed treatment . hence , it is necessary to give these patients other therapeutic alternatives with the intention of improving and controlling their symptoms . it is within this diagnostic - therapeutic framework that ptns was born as a possible alternative for the treatment of oab . ptns via surface electrodes was proposed in 1983 and , later , in 1987 , in animal experimentation , it was proven that it could inhibit detrusor hyperactivity as well as control urge incontinence . ptns is the electrostimulation of the sacral roots ( s2-s4 ) that produce an activation of the sacral plexus that controls the visceral organs and the pelvic floor muscles , thereby improving bladder control [ 12 - 14 ] . since then , some studies have been conducted to prove the efficacy of ptns versus other treatments and placebo for the treatment of oab . conducted a randomized clinical trial comparing ptns with placebo in 37 women and reported significant improvement regarding frequency and nocturia after the stimulation , although both quality of life , as assessed by questionnaire , and micturitional urgency improved in both groups without significant differences . .   carried out a study with 44 patients with oab treated with ptns , without a control group , and reported improvement in urodynamic parameters , both in the maximum cystometric capacity and in the time of onset of the first involuntary detrusor contraction . peters et al .   in 2009 published a clinical trial in which they compared tolterodine with ptns in 100 patients with oab . ptns showed clinical improvement in 79.5% of the patients versus improvement in 54.8% of patients who took tolterodine 4 mg . in a group of 43 patients with oab that did not respond to medical treatment with anticholinergics , yoong et al . tested a protocol of ptns for 6 weeks ( 6 sessions ) and saw a positive response in 69.7% of the patients . in those who responded to the treatment , significant decreases in nocturia and micturitional urgency were observed and quality of life improved , although the therapy duration in this study needs to be clearly defined , a point that is currently not clear . analyzed the urodynamic changes in oab patients treated with ptns and found an objective improvement rate of 56% of the patients , with an increase in bladder capacity . in a small percentage of cases , bladder hyperactivity decreased , leading to the conclusion that ptns treatment may cause an increase in cystometric capacity as other clinical studies seem to suggest . proved , in a controlled clinical trial with placebo , that ptns leads to improvement in 71% of patients versus 0% in a control group , and there was also improvement in the treatment group for the number of incontinence episodes , micturitional volume , and quality of life compared with the placebo . in relation to the aforementioned results , our study showed clinically significant improvements in diurnal micturitional frequency , micturitional urgency , and urge incontinence , but not in nocturia , which is one of the symptoms that most affects the patients ' quality of life . also , the subjective improvement of the patients was 50% , similar to previous studies in which the rate ranged between 56% and approximately 70% . however , in patients with no objective improvement , we did observe clinical improvement when the patients handed over their 48-hour micturitional calendar . one of the discussions about this therapy , apart from its clinical efficacy , is the application time and whether maintenance treatment must be applied . regarding this , it seems that treatment with at least 12 continuous sessions leads to improvement of symptoms that can last for at least 12 months . some authors even recommend that if the ptns treatment has been effective , it must be maintained , because it seems to stabilize the disease and improve the quality of life of these patients . in conclusion , ptns in patients with oab refractory to treatment with anticholinergics is currently a valid and safe alternative , with an acceptable success rate , and does not increase the morbidity of the patient nor prevent the patient from undergoing another kind of treatment .
purposeoveractive bladder ( oab ) is a clinical syndrome that is currently treated initially with anticholinergics , although some other therapeutic alternatives exist , such as neuromodulation , botulinum toxin , and posterior tibial nerve stimulation ( ptns ) . 
 the purpose of this study was to assess the efficacy of ptns in patients with oab refractory to anticholinergics.materials and methodswe present a cohort study of 14 women with oab to whom we applied ptns . 
 we assessed ( before and after the treatment ) the diurnal micturitional frequency , the nocturnal micturitional frequency , urgency episodes , and urge incontinence episodes . 
 results were analyzed by using the wilcoxon test for nonparametric samples.resultswe observed statistically significant improvement in the diurnal micturitional frequency ( p=0.05 ) , in episodes of micturitional urgency ( p=0.03 ) , and in episodes of urge incontinence ( p=0.004 ) . 
 a total of 50% of the patients felt subjective improvement from their pathology.conclusionsptns is a valid , minimally invasive treatment option with minimum morbidity for patients with oab refractory to treatment with anticholinergics .