728 J. GROEN and J.L.H.R. BOSCH

FIg. 4. SANS with stlmulatlon nccdlc andground pad.

Evidence. McGuire et aI. [35] used acupuncture points

in TENS and obtained good symptomatic results; Chang

[50] was the first to report results with the needle

technique; showing statistically significant changes in

the maximum cystometric capacity and maximum flow

rate in a group of 26 women immediately after a 30-min

treatment. Such changes were absent in a controI group

of 26 women. ln addition, the proportion ofpatients who

became stabIe and had subjective symptomatic improve-

ment was greater in the treated group. Despite these

promising results from the technique, it did not

appear in uroIogical practice until a commercial version

(PercSANS@) became avaiIabIe recentIy. Most of the

results of SANS to date are reported onIy in abstracts.

Clínical success rates of 67-81% were reported during

the lCS and EAU congresses of 1999 and 2000.

Urodynamic results were reported by Klingler et aI.

[51], who found that bIadder instability was eradicated

in nine of 13 patients and improved in one. The bladder

capacity increased significantIy from a mean of 197 to

252 mL.

Long-term resuIts. Stoller [52] described an 81 % clinical

success rate in 90 patients after a mean follow-up of

5.1 years. Patients were treated continuously with

increasing intervals between treatments; some patients

treated themselves at home. These promising results

were a reason to start the development of a minimally

invasive peripheral implant device. No side-eITects have

been reported.

Magnetic stimulation

An electric current, e.g. through a coil, induces a mag-

netic field; and a changing magnetic field in tum induces

an electric field. These physical laws can be applied to

stimulate the sacral roots or the pudendal nerves

noninvasively using a 'magnetic field. This is possible

because body tissues do not significantly attenuate such

a field, but in contrast have a high electrical impedance.

FIg. 5. Commcrclally avallablc chalr for magnctlc stlmulatlon.

The advantage of magnetic stimulation over electrical

stimulation is therefore that the stimulation intensity

at the leveI of the nerves can be high [53]. Reports of

magnetic stimulation in the context of the overactive

bladder aImost alI originate from two groups.

Technique. McFarlane et aI. [54], who to date have

applied magnetic stimulation for research purposes only,

pIace a specially designed coil tangentially over the sacral

skin and connect it to a stimuIator. The muscle response

of the toes (or the EMG response of the toe flexors to single

pulses) is used for correct positioning of the coi!. The

optimal position is usually = 10 cm beIow the iliac crests

and 5 cm lateral to the midline [54]; stimulation lasts for

2-5 s. Yamanishi et aI. [55] developed a chair with a coil

and a cooling system in its seat; patients are instructed to

sit so that the anns is positioned at the centre of the coil

and so that the highest anal contraction is felt during

stimulation (Fig. 5). Patients are treated twice a week

for 5 weeks; one session lasts 15 min with cycles of

60 s on/30 s oIT.

.

Evidence. The group lead by Craggs was the first to

show that magnetic stimulation of 83 acutely suppresses