Treating Overactive Bladder Syndrome with Interstim Therapy

The International Continence Society has defined overactive bladder, or OAB, as urgency, with or without urge incontinence, often accompanied with nocturia and frequency in the absence of metabolic or local factors elucidating these symptoms.

Comparison of a normal (left) vs an overactive bladder (right). © Lightspring/

Overactive Bladder

Approximately 1 in 11 adults, especially older adults, are affected by OAB. This disorder occurs when the muscular wall of the bladder contracts rapidly, causing urinary urgency—an instant uand unpreventable urge to urinate. There are certain nervous system disorders that may cause OAB. These include strokes, spinal cord injury, dementia, Parkinson’s disease, diabetic neuropathy, and multiple sclerosis, although the factors that cause OAB in majority of patients are not clear.

Treatment may comprise of medications, behavioral therapy, and pelvic muscle strengthening. Previously, pharmacotherapy was looked at as the standard treatment for OAB, but this procedure has been associated with several side effects such as dry eyes and mouth, blurry vision, and constipation. Moreover, studies have demonstrated poor long-term patient compliance with OAB medications.

Interstim Therapy

Interstim therapy is useful for patients who are not able to tolerate anticholinergic medications or have refractory OAB. In this treatment, the pelvic nerves (S-3 nerve root) are electrically stimulated, but mildly, through centrally implanted electrodes in the sacral foramen. While the actual mechanism of action is not fully understood, it has been hypothesized that the normal micturition reflex is moderated by sacral neuromodulation, which activates the somatic afferent inhibition of sensory processing of the bladder inside the spinal cord.

Interstim therapy involves two steps—a test phase and implantation phase. While the initial test phase can be carried out either in the operating or office room, the full implantation is invariably conducted in the operating room under anesthesia.

At the time of test phase, the permanent tined lead (when carried out in the operating room) or a temporary test lead wire (when carried out in office) is first passed via the S-3 foramen and then linked to an external stimulator. After completing the test phase, pre- and post-procedure voiding diaries are used to assess the patient. Full implantation is given to patients who show a positive test response, that is, 50% or more improvement to baseline. Following a successful test phase, the battery is implanted in the operating room.


Studies have demonstrated prospective outcomes with interstim therapy for OAB. In fact, one study showed as much as 84% satisfaction among patients who use this therapy. There was another study which reported that 76% of patients were able to achieve success at just six months when compared to 49% of patients who used medications. Generally, interstim therapy has been shown to be an effective and safe option for patients suffering from refractory OAB, with excellent long-term efficacy.



This article has been adapted from content authored by Dr. Mohamed Akl and Dr. Ahmed Akl at the AZ Urogynecology and Pelvic Health Center.

About AZ Urogynecology and Pelvic Health Center

The AZ Urogynecology and Pelvic Health Center is devoted exclusively to the diagnosis and treatment of all urogynecologic, pelvic floor disorders and complex gynecologic problems.

They offer a wide array of advanced diagnostic tools and specialized treatment options.

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Last updated: Jun 28, 2018 at 3:19 AM

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