Is InterStim (sacral nerve stimulation) used to treat hyperactive bladder?

Sacral Nerve Stimulation (InterStim) for Overactive Bladder

Yes, sacral nerve stimulation (SNS), including the InterStim system, is an established and effective third-line treatment option for patients with overactive bladder (OAB) who have failed behavioral and pharmacologic therapies. 1

Treatment Algorithm for Overactive Bladder

1. First-line treatment: Behavioral therapies

   • Bladder training
   • Pelvic floor exercises
   • Fluid management
   • Weight loss if patient is obese

2. Second-line treatment: Pharmacologic management

   • β3-adrenoceptor agonists (preferred first due to lower cognitive side effects)
   • Antimuscarinic medications (with caution in elderly or those with cognitive concerns)
   • Combination therapy with both medication classes for refractory cases

3. Third-line treatment: Minimally invasive procedures

   • Sacral neuromodulation (SNM/InterStim)
   • Peripheral tibial nerve stimulation (PTNS)
   • Intradetrusor botulinum toxin injection

Sacral Nerve Stimulation for OAB

Efficacy

SNM has demonstrated sustained effectiveness for OAB symptoms with long-term follow-up:

• 67% therapeutic success rate at 5 years 2
• Significant reduction in urinary frequency and urgency episodes 3
• Complete continence rates of 44% in newly implanted patients after 5 years 3
• Significant improvements in quality of life measures 2

Patient Selection

SNM is specifically indicated for:

• Patients who have failed or are intolerant to behavioral and pharmacologic therapies 1
• Patients with moderate to severe OAB symptoms affecting quality of life 1
• Patients willing to undergo a surgical procedure and manage the device 1

Procedure

The procedure is typically performed in two stages:

1. Trial phase: Temporary lead placement to assess effectiveness
2. Permanent implantation: If trial shows ≥50% symptom improvement

Available Systems

Multiple SNM systems are available:

• InterStim system (Medtronic) - established with long-term data 4
• Axonics system - rechargeable with 15+ year battery life 5
• BetterStim system - newer alternative with comparable outcomes 6

Advantages and Considerations

Advantages

• Provides an option for patients who fail conservative treatments
• Offers sustained symptom improvement over many years
• Test stimulation phase allows prediction of long-term success
• Reversible treatment option

Potential Complications

• Device-related adverse events occur in approximately 51% of patients 3
• Common issues include undesirable changes in stimulation (22%), implant site pain (15%), and device ineffectiveness (13%) 2
• Surgical revisions required in 39% of patients over 5 years 3

Clinical Pearls and Pitfalls

1. Patient expectations: Counsel patients that SNM typically improves symptoms rather than providing complete cure

2. Screening process: The test stimulation phase is crucial for identifying appropriate candidates before permanent implantation

3. Follow-up: Regular follow-up is essential to monitor effectiveness and manage potential device issues

4. Contraindications: Patients should be screened for conditions that might interfere with device function or increase surgical risk

5. Shared decision-making: The 2024 AUA/SUFU guidelines emphasize that minimally invasive therapies like SNM may be offered without requiring trials of behavioral or pharmacologic management in appropriate cases through shared decision-making 1

In conclusion, sacral nerve stimulation with systems like InterStim is a well-established, effective third-line treatment option for overactive bladder with sustained long-term benefits for appropriately selected patients.