*2.2.9.5 Unanticipated adverse events and complications*

It is important to understand that although rare, complications are an important predictor of SNM reoperation and may result in severe morbidity [75, 78]. Rare complications of lead placement and implantation have been reported in separate case reports and limited series, including one case of retroperitoneal hemorrhage after SNM implanted for urge incontinence [79]. Another case of lead migration into the sigmoid colon during implantation was complicated by and presented as a colocutaneous fistula [80].

### **2.3 Direct PNS**

As our understanding grew of the neurological contribution and circuits from the sacral nerve roots, new-found focus has been on stimulation of the whole pudendal nerve as it originates from its S2, S3 and S4 nerve roots, and not just the S3 nerve root as with SNM. Theoretically, this should provide a more inclusive sacral nerve stimulation than targeting S3 alone, resulting in inhibition of the micturition reflex and controlling uninhibited detrusor contractions while increasing bladder capacity [14]. This was the hypothesis of the early work on PNS, proposing it would particularly benefit neurogenic bladder patients who fared less successfully with SNM [5].

By placement of both a sacral and pudendal tinned leads in Alcock's canal either tranperineally or through a posterior approach, continuous electrical stimulation similar to SNM is delivered to both nerves [5]. One group of researchers demonstrated comparable improvements in voiding parameters between the PNS and SNM groups, but subjective superiority for PNS reported by patients [81]. PNS was not only found to improve continence but increase bladder capacity in neurogenic bladder patients [5]. Another variation of pudendal PNS is dorsal genital nerve stimulation (DGN), the pudendal nerve's most anterior branch, and this may be the next therapeutic alternative [5, 82].

### **2.4 Peripheral, cutaneous and minimally invasive neuromodulation modalities**

Bypassing the need for formal implantation of any device, these varied modalities of neuromodulation employ concepts on transmitted electrical stimulatory signals from the skin to the nerve vicinity or from peripheral nerves to more central sacral nerve roots and in turn, resulting in a modulatory effect and control on reflex bladder activity particularly bladder hyperactivity, neurogenic or non.

### *2.4.1 Posterior tibial nerve stimulation*

### *2.4.1.1 Mode of effect*

Posterior tibial nerve stimulation (PTNS) provides indirect and retrograde electrical stimulation to the posterior tibial nerve as it passes posteriorly to the medial malleolus of the ankle; the posterior tibial nerve is a mixed nerve with roots from L4 to S3, and as such, provides its modulatory effects on sacral complex roots involved in the lower urinary tract through activation of somatic fibers and inhibiting bladder contractions [1, 15, 83].

PTNS is performed by placement of a needle superoposteriorly to the medial malleolus and a grounding pad placed on the sole of the foot laterally (**Figure 7**). The needle is connected to the stimulator device, and low-voltage stimulation is applied: correct placement is confirmed when flexion of the greater toe is observed and the patient reports sensations from the sole of the foot [84]. Treatment sessions are repeated weekly for a period of 12 weeks and in 30-minute sessions. Repeat session cycles are possible [85].

One of the advantages of PTNS is a "carryover" effect. This has been described as continued symptomatic improvement not necessarily just during the nerve stimulation sessions, which is in contrast to the loss of efficacy when the SNM device is switched off. Many studies have examined the carryover effect and what implications it may have in devising PTNS regimens and schedules, with variable success [84, 86, 87].

Another advantage of PTNS is the fact it can be administered by any healthcare provider or the patient themselves after appropriate training. As a matter of fact,

**227**

costs [93].

*Neuromodulation in Urology: Current Trends and Future Applications*

home administration systems and micro implants are being developed for that sole

In an effort to identify ideal candidates for PTNS treatment in OAB, a number of investigators identified that history of prior SNM therapy correlated negatively with PTNS outcomes. On the other hand, more severe complaints of urge urinary incontinence and urinary bladder volume at first sensation (a UDS parameter) were

Efficacy of PTNS as evident from review of 4 randomized controlled trials, none of which pinned comparison against SNM, showed a majority of patients were able to achieve at least 50% improvement from baseline complaint; these studies ruled out the possibility of a hypothesized placebo effect, according to the reviewers. A substantial complaint from PTNS treatment was temporary foot

Several trials have also compared PTNS to medical treatment of OAB, including the OrBIT trial, and reported comparable if not somewhat superior results with a lower side effect profile, particularly dry mouth and constipation among other side

Utilizing needles applied transcutaneously to stimulate the posterior tibial nerve, this modality of treatment has been investigated for MS and OAB patients [9]. There are limited studies that demonstrate variable improvements for OAB patients with transcutaneous tibial nerve stimulation (TTNS). Perhaps its advantages stem from its safety and fairly minimal adverse events profile, and its low

effects associated with anticholinergic medication [85, 91, 92].

*2.4.2 Transcutaneous tibial nerve stimulation*

purpose [84, 88]. PTNS, too, is less costly than SNM, on average [89, 90].

*DOI: http://dx.doi.org/10.5772/intechopen.92287*

*2.4.1.2 Predictors of PTNS success*

*Posterior tibial nerve stimulation.*

predictors of PTNS success [90].

*2.4.1.3 Efficacy of PTNS*

pain [74].

**Figure 7.**

*Neuromodulation in Urology: Current Trends and Future Applications DOI: http://dx.doi.org/10.5772/intechopen.92287*

**Figure 7.** *Posterior tibial nerve stimulation.*

*Neurostimulation and Neuromodulation in Contemporary Therapeutic Practice*

As our understanding grew of the neurological contribution and circuits from the sacral nerve roots, new-found focus has been on stimulation of the whole pudendal nerve as it originates from its S2, S3 and S4 nerve roots, and not just the S3 nerve root as with SNM. Theoretically, this should provide a more inclusive sacral nerve stimulation than targeting S3 alone, resulting in inhibition of the micturition reflex and controlling uninhibited detrusor contractions while increasing bladder capacity [14]. This was the hypothesis of the early work on PNS, proposing it would particularly benefit neurogenic bladder patients who fared less successfully with SNM [5]. By placement of both a sacral and pudendal tinned leads in Alcock's canal either tranperineally or through a posterior approach, continuous electrical stimulation similar to SNM is delivered to both nerves [5]. One group of researchers demonstrated comparable improvements in voiding parameters between the PNS and SNM groups, but subjective superiority for PNS reported by patients [81]. PNS was not only found to improve continence but increase bladder capacity in neurogenic bladder patients [5]. Another variation of pudendal PNS is dorsal genital nerve stimulation (DGN), the pudendal nerve's most anterior branch, and this may be the next

**2.4 Peripheral, cutaneous and minimally invasive neuromodulation modalities**

Posterior tibial nerve stimulation (PTNS) provides indirect and retrograde electrical stimulation to the posterior tibial nerve as it passes posteriorly to the medial malleolus of the ankle; the posterior tibial nerve is a mixed nerve with roots from L4 to S3, and as such, provides its modulatory effects on sacral complex roots involved in the lower urinary tract through activation of somatic fibers and inhibit-

PTNS is performed by placement of a needle superoposteriorly to the medial malleolus and a grounding pad placed on the sole of the foot laterally (**Figure 7**). The needle is connected to the stimulator device, and low-voltage stimulation is applied: correct placement is confirmed when flexion of the greater toe is observed and the patient reports sensations from the sole of the foot [84]. Treatment sessions are repeated weekly for a period of 12 weeks and in 30-minute sessions. Repeat

One of the advantages of PTNS is a "carryover" effect. This has been described

Another advantage of PTNS is the fact it can be administered by any healthcare provider or the patient themselves after appropriate training. As a matter of fact,

as continued symptomatic improvement not necessarily just during the nerve stimulation sessions, which is in contrast to the loss of efficacy when the SNM device is switched off. Many studies have examined the carryover effect and what implications it may have in devising PTNS regimens and schedules, with variable

bladder activity particularly bladder hyperactivity, neurogenic or non.

Bypassing the need for formal implantation of any device, these varied modalities of neuromodulation employ concepts on transmitted electrical stimulatory signals from the skin to the nerve vicinity or from peripheral nerves to more central sacral nerve roots and in turn, resulting in a modulatory effect and control on reflex

**2.3 Direct PNS**

therapeutic alternative [5, 82].

*2.4.1 Posterior tibial nerve stimulation*

ing bladder contractions [1, 15, 83].

session cycles are possible [85].

success [84, 86, 87].

*2.4.1.1 Mode of effect*

**226**

home administration systems and micro implants are being developed for that sole purpose [84, 88]. PTNS, too, is less costly than SNM, on average [89, 90].

### *2.4.1.2 Predictors of PTNS success*

In an effort to identify ideal candidates for PTNS treatment in OAB, a number of investigators identified that history of prior SNM therapy correlated negatively with PTNS outcomes. On the other hand, more severe complaints of urge urinary incontinence and urinary bladder volume at first sensation (a UDS parameter) were predictors of PTNS success [90].

### *2.4.1.3 Efficacy of PTNS*

Efficacy of PTNS as evident from review of 4 randomized controlled trials, none of which pinned comparison against SNM, showed a majority of patients were able to achieve at least 50% improvement from baseline complaint; these studies ruled out the possibility of a hypothesized placebo effect, according to the reviewers. A substantial complaint from PTNS treatment was temporary foot pain [74].

Several trials have also compared PTNS to medical treatment of OAB, including the OrBIT trial, and reported comparable if not somewhat superior results with a lower side effect profile, particularly dry mouth and constipation among other side effects associated with anticholinergic medication [85, 91, 92].

### *2.4.2 Transcutaneous tibial nerve stimulation*

Utilizing needles applied transcutaneously to stimulate the posterior tibial nerve, this modality of treatment has been investigated for MS and OAB patients [9]. There are limited studies that demonstrate variable improvements for OAB patients with transcutaneous tibial nerve stimulation (TTNS). Perhaps its advantages stem from its safety and fairly minimal adverse events profile, and its low costs [93].

### *2.4.3 Transcutaneous electrical nerve stimulation*

As the name suggests, this modality is applied to areas in close proximity to target internal nerves. These include the pudendal nerve, be it through transcutaneous stimulation in the vagina in a female or in the perineal region in the male, or both the pudendal and sacral nerves when applied to the sacral skin. DGN is also a form of transcutaneous electrical nerve stimulation (TENS). It is advocated as a less invasive and low-cost neuromodulation system that can also be taught to patients for self-application [5].

Multiple small-sized trials have demonstrated improvements in symptom scores and efficacy in patients with refractory OAB or MS with bladder hyperactivity. However, although it is safe, the durability of its effect has been called into question [9, 94].
