Chronic pelvic pain (CPP) is perceived in the lower quadrants of the abdomen and its symptoms may be either ongoing or intermittent (lasting for more than six months).
The causes behind CPP may be either organ related or belonging to the gender diseases group.
CPP treatment needs to be approached by a multidisciplinary team so that the application of a third tier therapy may be useful for the treatment of pain and the functional symptoms.
On this study CPP is treated according to the retrograde posterior tibial nerve (PTN) ischiatic neuromodulation technique.  
Posterior tibial nerve (PTN) is a mixed sensitive and motor nerve stemming from L4-S3 roots, which modulate the nerve activity of pelvic organs. The mechanism of action behind repetitive PTN stimulation is based on the attempt of inhibiting the nociceptive neurons on the spinothalamic tract.
Such PTN neuromodulation retrograde approach represents the last therapeutic step which follows several first and second tier therapies: anesthetic block followed by pulsed radiofrequency (PRF) on all pelvic pain peripheral branches, anesthetic block followed by PRF on ganglion impar (also known as ganglio of Walther or azygos), PRF on dorsal lumbosacral roots.

We hereby present an observational retrospective study with a 33 months follow up on 12 patients (3 male, 9 female) where CPP is treated according to the retrograde PTN ischiatic neuromodulation technique by means of application of peripheral neuromodulation to the ischiatic nerve through surgical positioning of a three-electrode-implantable lead connected to the External Pulse Transmitter (EPT, Stimrouter, Bioness Inc, Valencia, US).
We have decided to place the lead on the ischiatic nerve in order to prevent any chance of lead decubitus which may arise should the lead be positioned next to the malleoulus. The device is exclusive as it provides the chance of treating both chronic pelvic pain (CPP), urinary and fecal incontinence.  Surgical lead positionining is performed through a mini-open approach by means of a medial longitudinal incision of the thigh (either left or right), 5cm to the apex of the popliteal fossa: we then open and provide divulsion of muscular fascia, followed by isolation of the sciatic nerve and then cut through the perineurium and finally insert the lead. Lead fixation is ensured by application of a fibrin sealant.
Patients have been enrolled according to our database. In the study design we have divided CPP causes into four groups: urinary retention, detrusor hyperactivity, pelvic pain syndromes and neurological bladder disfunctions.
Inclusion criteria are as follows: eligible patients must be at least 18+ yrs old, NRS>5, patients need filling out the medical informed consent, patients need to be adherent to all scheduled follow ups and be capable of managing the device.
Exclusion criteria are damage to the tibial nerve, coagulation disorders, ongoing systemic infection onto the incision site, major psychiatric disorders, less than one year life expectancy.

At the end of the follow-up period, collected data reports that:
•	NRS was reduced by 60%.
•	Quality of life of patients enrolled in the study was assessed by SF 36 questionnaire, which shows that 9 out of 12 patients were very satisfied and 3 patients were satisfied after procedure.
•	The reduction in the number of drugs taken prior to the neuromodulation treatment was between 80-100%: opiate reduction by 80%, adjuvant drugs by 60%, nutriceutics by 100%. The reduction in opioid intake is statistically significant.

In particular, the median values of morphine administered at the beginning and at the end of follow-up period (27.5 and 0.0, respectively) significantly differed (p=0.0004).  Moreover, the significantly decreasing trend identified in the use of morphine during the treatment period was shown to be statistically significant (p<0.0001).

The stimulation parameters found in our retrospective study report an important recommendation:
-the frequency of stimulation is functional to the specificity of the treatment: for pain frequency may range from 70 Hz to 100 Hz while for the treatment of both urinary and fecal incontinence from 10 Hz to 20 Hz.
-the minimum pulse width may range between 70 and 100 µsec.
-delivered current may vary between 0.4 mA and 2.7 mA.
It is reported that the average daily stimulation in order for the therapy to be effective is 7 hours, with a minimum time of 2 hours and a maximum time of 12 hours.
The 33-month study duration shows that there is no adaptation to the stimulation of the tibial nerve.

A multiplicity of studies about the treatment of CPP with neuromodulation techniques are available. 
The most interesting neuromodulation techniques are sacral nerve stimulation (SNS), and, above all, posterior tibial nerve (PTN) neurostimulation due to its less invasiveness.
To date, all examined studies regarding posteriors tibial nerve stimulation present a short time follow up (less than 6 months).
In our retrospective study we emphasize how effective the treatment of PTN neuromodulation by sciatic nerve approach is in terms of both pain and improvement of fecal and urinary incontinence over time.
At 33 months treatment of both pain and urinary/fecal incontinence has not lost its effectiveness and overall daily stimulation time has been reduced.

Posterior tibial nerve stimulation via the ischiatic nerve may represent a valid multifunctional alternative to the treatment of CPP when compared to other neuromodulation techniques such as SNS.
In conclusion, we may consider PTN stimulation through surgical isolation of the sciatic nerve to be effective given the demonstrated reduction in the use of drugs, especially opiates and the improvement in the patient’s quality of life highlighted by the resumption of his work and normal daily life conditions.

Efficacy and Safety of Sacral and Percutaneous Tibial Neuromodulation in Non-neurogenic Lower Urinary Tract Dysfunction and Chronic Pelvic Pain: A Systematic Review of the Literature. Tutolo M, Ammirati E, Heesakkers J, Kessler TM, Peters KM, Rashid T, Sievert KD, Spinelli M, Novara G, Van der Aa F, De Ridder D.
Clinical utility of neurostimulation devices in the treatment of overactive bladder: current perspectives. Janssen DA, Martens FM, de Wall LL, van Breda HM, Heesakkers JP.