====== InterStim ======

The implanted InterStim™ II system electrically stimulates the sacral nerve, which is thought to normalise neural communication between the [[bladder]] and [[brain]] and between the [[bowel]] and [[brain]]
((Leng WW, Chancellor MB. How sacral nerve stimulation neuromodulation works. Urol Clin North Am. 2005;32:11-18.))
((Patton V, Wiklendt L, Arkwright JW, Lubowski DZ, Dinning PG. The effect of sacral nerve stimulation on distal colonic motility in patients with fecal incontinence. Br J Surg. 2013;100:959–968.))
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In the early 1980s Tanagho and Schmidt began developing an implantable sacral electrode that would provide the basis for the concept of [[sacral neuromodulation]] (SNM) and the [[InterStim]] device ([[Medtronic]])
((Tanagho EA, Schmidt RA, Orvis BR. Neural stimulation for control of voiding dysfunction: a preliminary report in 22 patients with serious neuropathic voiding disorders. J Urol. 1989 Aug;142(2 Pt 1):340-5. doi: 10.1016/s0022-5347(17)38751-7. PMID: 2787411.)).
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It is indicated for refractory [[urinary urgency]], frequency, urge [[incontinence]], non-obstructive [[urinary retention]], and [[fecal incontinence]]. If a [[trial]] with a temporary lead placed adjacent to the [[sacral nerve]] via the [[S3]] foramen produces>50% reduction in symptoms, it is connected to an [[implantable pulse generator]]. [[mechanism of action]] is poorly understood but may modulate the afferent signals of the [[micturition reflex]]
((Sukhu T, Kennelly MJ, Kurpad R. Sacral neuromodulation in overactive bladder: a review and current perspectives. Res Rep Urol. 2016; 8:193–199))
Improvement in symptoms is seen in up to 70% of patients with complete resolution in incontinence around 39%
((Herbison GP, Arnold EP. Sacral neuromodulation with implanted devices for urinary storage and voiding dysfunction in adults. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD004202. doi: 10.1002/14651858.CD004202.pub2. PMID: 19370596.)).
Contraindications to implantation include failure to improve with trial and the likely need for repeated MRIs in the future (the device is MRI conditional for head only with ≤ 1.5 Tesla MRI).