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 [9
]. 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 [10
]. 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 [11
]. 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 [12
]. 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
Since then, some studies have been conducted to prove the efficacy of PTNS versus other treatments and placebo for the treatment of OAB. Bellette et al. [14
] 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. Amarenco et al. [15
] 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. [16
] 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. [17
] 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. Vandoninck et al. [18
] 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. However, it is not useful to abolish the detrusor hyperactivity. Finazzi-Agro et al. [19
] in 2010 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. It is possible that this improvement did not live up to their expectations.
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 [20
]. 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 [21