How Stratus Radiofrequency Is Performed: Step-by-Step Procedure

Stratus radiofrequency ablation (RFA) is a minimally invasive pain management technique that has been refined to provide long-lasting relief for patients with sacroiliac joint (SIJ) pain and certain cervical pain syndromes. Unlike conventional RF methods, Nimbus Stratus technology utilizes a multi-tined bipolar electrode that creates a continuous strip lesion, capturing a larger portion of the target nerve network.

Pre-Treatment Assessment and Diagnostic Protocols

The effectiveness of Nimbus Stratus RFA depends on precise diagnosis:

• Diagnostic PSN Blocks: Patients undergo sacral lateral branch blocks (PSN) to confirm the SIJ as the pain generator.
  
• Response Criteria: A ≥50% pain reduction after diagnostic blocks is required to proceed.
  
• For Cervical Indications: Targeting the third occipital nerve (TON) or cervical medial branches requires dual diagnostic blocks to increase specificity.
  
• Imaging: MRI or CT scans help rule out alternative causes such as radiculopathy or structural pathology.

Patient Preparation and Imaging Guidance

Preparation ensures a safe and effective intervention:

• Positioning: Prone positioning for SIJ ablation; slight obliquity for cervical procedures.
  
• Sedation: Conscious sedation is typically employed, allowing the patient to respond during testing.
  
• Imaging Guidance:
  
  • Fluoroscopy: Standard method for real-time visualization.
    
  • Ultrasound: Optional in specific cases to minimize radiation exposure.
    
• Sterility: Strict sterile field preparation prevents infection.

Technical Execution and Device Settings

Nimbus Stratus technology allows precise, reproducible lesioning:

• Electrode Placement: Under fluoroscopy, the multitined electrode array is inserted parallel to the sacral foramina for SIJ or along the articular pillar for cervical targets.
  
• Stimulation:
  
  • Sensory (50 Hz) confirms proximity to target nerves.
    
  • Motor (2 Hz) ensures no involvement of motor roots.
    
• Ablation Parameters:
  
  • Continuous RF: Typically 85°C for 180 seconds (COBRA-SIJ protocol).
    
  • Pulsed RF: Used in cases where neuromodulation without nerve destruction is preferred.
    
• Outcome: The bipolar lesion achieves >95% neural capture of PSN, compared to <15% with monopolar RF.

Duration of Pain Relief and Retreatment Intervals

Findings from the COBRA-SIJ and other protocols show:

• Sustained pain relief for 12–24 months in most patients.
  
• Functional improvement documented by ODI, EQ-5D, and NPRS scores.
  
• Repeatability: Retreatment is safe and effective, typically performed when symptoms recur after 18–24 months.

Post-Procedure Care and Monitoring

Post-procedure care focuses on safety and functional recovery:

• Observation: 30–60 minutes monitoring for immediate adverse reactions.
  
• Pain Management: Mild post-procedural discomfort is common and self-limiting.
  
• Recovery: Patients usually return to normal activity within 24–48 hours.
  
• Follow-Up: Scheduled evaluations at 1, 3, 6 months, and annually.

Safety Profile and Patient Tolerability

Nimbus Stratus RFA has a favorable safety profile:

• Complication rates are extremely low (<0.1%).
  
• Adverse Events: Minor and transient (e.g., soreness, numbness).
  
• Patient Tolerability: High, with minimal recovery time and excellent clinical outcomes.
  
• Safety Enhancements: The use of sensory and motor stimulation minimizes the risk of nerve injury.

References

1. Aaron Conger, DO et al.
   “Conventional or Bipolar Radiofrequency Ablation for the Treatment of Sacroiliac Joint Pain? The COBRA-SIJ Study, a Double-Blind, Randomized, Comparative Trial.”
   University of Utah, Department of Physical Medicine and Rehabilitation, Protocol Version 3.0, January 3, 2023.
   
2. Eldon Y. Loh, MD; Anne M. Agur, PhD; Robert S. Burnham, MD.
   “Ultrasound-Guided Radiofrequency Ablation for SI Joint Pain: An Observational Study.”
   Spine Intervention Society, Elsevier (Pre-proof), 2022.
   
3. Stratus Medical, Regulatory Division.
   “Nimbus Electrosurgical Radiofrequency Multitined Expandable Electrode – Indications for Use and FDA 510(k) Clearance.”
   US FDA Device Evaluation, Class II Neurology Device, K-121773, 2012.
   
4. IRB Approval Document – Stratus Medical Protocol.
   “Prospective Cohort Study of Cervical Radiofrequency Ablation for Axial Neck Pain with Nimbus RFA (TON/C3 & C4 Medial Branch).”
   WCG IRB Approval, Sponsor Protocol Number Stratus_001, 2021.