InterStim or Sacral Nerve Stimulation


Millions of people suffer from frustrating and embarrassing bladder control problems that make them feel trapped by a fear of leaking, or not being close to a bathroom when they are out of their home. Treatments such as medications, behavior modification, diet changes, pelvic floor exercises, or the use of a catheter, can be effective for many patients, but there are still others who do not respond well to these therapies. 

Sacral Nerve Stimulation (SNS) is a surgical option that involves a small implanted device that can be thought of as a pacemaker for the bladder. InterStim® therapy is a sacral nerve stimulation therapy developed by Medtronic that was approved for use by the U.S. Food and Drug Administration (FDA) in 1997. This device has been successfully implanted to treat thousands of patients worldwide. 

InterStim® therapy employs a small implanted medical device that sends mild electrical pulses to the nerves located just above the tail bone. These nerves are called sacral nerves. The sacral nerves activate or inhibit muscles and organs that contribute to urinary control. These include bladder, sphincter and pelvic floor muscles. This electrical stimulation is designed to facilitate communication between the brain and the bladder in order to eliminate, or reduce, certain bladder control functions. 


Sacral nerve stimulation is intended for patients who have failed or cannot tolerate more conservative treatments. Bladder control problems that may improve with SNS therapy include:

  • Overactive bladder - includes urge incontinence, urgency and frequency
  • Urge incontinence - The involuntary loss of urine associated with a sudden, strong desire to void (urgency).
  • Urgency-frequency - Frequent, uncontrollable urges to urinate (urgency) and voiding often in very small amounts (frequency).
  • Urinary retention - The inability to empty the bladder
  • Fecal Incontinence - The inability to control your bowels


InterStim Therapy is not intended to treat or used by:

  • Stress incontinence - People with stress incontinence lose urine when they exercise, sneeze, cough, or laugh.
  • Mechanical obstructions - Enlarged prostate (benign prostatic hyperplasia or BPH), cancer or narrowing of the urethra (urethral strictures).
  • Patients with pacemakers
  • Pregnant women
  • Diabetic patients
  • Patients with neurological diseases such as Multiple Sclerosis
  • Patients under 16 years of age


Before starting SNS therapy, a provider will initiate two tests to determine if this therapy will be effective for the patient.

Basic Test

This is an in-office procedure in which temporary leads are placed into the sacral nerve using a local anesthesia. After the leads are placed, a test will be performed to insure that the sacral nerve is being stimulated. This can be easily verified by the movement of the big toe. Regardless of overall test outcomes, these leads will be removed in the office after one week.

Advanced Test

This test is performed in the operating room on an out-patient basis. This is generally indicated for patients who have urinary retention, and in which a longer sacral nerve stimulation is necessary. Rather than placing temporary leads, this procedure uses one long-term lead that is left in the sacral nerve for a minimum of two weeks. If the patient is recommended for permanent placement of the InterStim® device, this lead will remain in place and be connected to the InterStim® after the test period is complete. If the patient is not recommended for the InterStim®, they will still require a second surgery to remove the long-term lead.


Implantation of the InterStim® device is performed in an operating room. Your doctor will discuss the type of anesthesia to be used - either pain medication with a sedative or general anesthesia. Two incisions will be made in the buttocks where the device will be placed under the skin. The incision for the neurostimulator will be about 2 inches long; a second incision will be about ½ inch or less. 

If a temporary lead was used for the test stimulation:

  • the lead will be removed
  • a long-term lead and neurostimulator will be implanted in the upper buttock or abdomen

If a long-term lead was used for the test stimulation:

  • the long-term lead will remain in place
  • the external wire used for test stimulation will be removed
  • a neurostimulator will be connected to the long-term lead and placed under the skin in the upper buttock or abddome


Some known limitations for this therapy include:

  • Failed test stimulation.
  • Inability to use the patient programmer.
  • MRI and other Imaging - Patients with an InterStim device CANNOT have an MRI without MRI protocol. In addition, patients cannot  have shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy (localized heating of body tissues with an electric current for medical or surgical purposes), anywhere on their body because pf the implanted neurostimulator. Energy can be transferred through the implanted system, and can cause tissue damage, severe injury or death.


As with any therapy, individual results may vary. Patients implanted with an InterStim® device can experience relief of many urinary symptoms, as well as an improved quality of life. However, implantation of the device is not guaranteed to result in complete improvement or cure.