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 1) 2)
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) 3).
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 4) Improvement in symptoms is seen in up to 70% of patients with complete resolution in incontinence around 39% 5). 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).