Is the New Ultrasound-Guided RFA Method Safer and More Effective for Treating SHPT?

Summary:

In patients with secondary hyperparathyroidism (n=103, mean age 50.8±12.8 years, 49 males), an improved ultrasound-guided radiofrequency ablation protocol involving parathyroidal circumferential hydrodissection, short electrode, low-power settings, and intra-nodular ablation (n=53) significantly increased clinical success rates (94.97% vs 89.07%) and reduced recurrent laryngeal nerve-related hoarseness (5.7% vs 18%) with faster recovery (1.63 vs 2.75 months) compared to conventional ultrasound-guided RFA protocol without hydrodissection or modified parameters (n=50), though it was associated with mild transient hoarseness in a small proportion of patients that resolved more quickly than with conventional technique.

Clinical Context

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease, characterized by parathyroid gland hyperplasia and elevated parathyroid hormone (PTH) levels in response to hypocalcemia, hyperphosphatemia, and vitamin D deficiency. Uncontrolled SHPT leads to renal osteodystrophy, cardiovascular calcification, and increased mortality. While medical management with phosphate binders, vitamin D analogs, and calcimimetics is first-line, refractory SHPT often requires parathyroidectomy.

Ultrasound-guided radiofrequency ablation has emerged as a minimally invasive alternative to surgery for SHPT, offering parathyroid tissue destruction without general anesthesia or surgical incision. However, the proximity of parathyroid glands to the recurrent laryngeal nerve (RLN) creates risk of thermal injury causing voice changes—the same concern that exists with thyroid and parathyroid surgery.

This prospective study evaluated technical modifications designed to improve both efficacy and safety of RFA for SHPT. The key innovations included hydrodissection (fluid injection creating a protective buffer zone), use of shorter electrodes for more precise ablation, lower power settings to reduce thermal spread, and intra-nodular (rather than peripheral) ablation technique. These modifications aim to achieve complete gland ablation while minimizing collateral thermal damage.

Clinical Pearls

1. Higher Success Rate with Improved Protocol: The 94.97% clinical success rate with the improved protocol versus 89.07% with conventional technique represents a meaningful improvement in efficacy. For patients with refractory SHPT, maximizing first-procedure success is important to avoid repeated interventions.

2. Dramatic Reduction in Nerve Injury: The reduction in RLN-related hoarseness from 18% to 5.7% represents a three-fold safety improvement. Hoarseness significantly impacts quality of life, particularly for patients who rely on their voice professionally. This reduction makes RFA more acceptable as a treatment option.

3. Faster Recovery When Hoarseness Occurs: Even when hoarseness occurred with the improved protocol, recovery was significantly faster (1.63 vs 2.75 months). This suggests less severe nerve injury—likely thermal stunning rather than more substantial damage—reflecting the protective effect of the modifications.

4. Hydrodissection Is Key: Circumferential hydrodissection creates a fluid buffer zone that both protects adjacent structures and provides acoustic contrast for better ultrasound visualization. This technique is transferable from thyroid ablation experience and represents best practice for parathyroid RFA.

Practical Application

For centers performing RFA for secondary hyperparathyroidism, adopt the improved protocol elements: circumferential hydrodissection before ablation, short electrode selection appropriate to gland size, conservative power settings, and intra-nodular ablation initiation. These modifications do not add substantial procedure time but significantly improve outcomes.

Hydrodissection technique involves injecting normal saline or 5% dextrose around the parathyroid gland to create separation from the tracheoesophageal groove where the RLN runs. Continuous visualization during injection confirms adequate buffer creation. The fluid also conducts heat away from critical structures.

For patient counseling, explain that while hoarseness risk exists, the improved technique has substantially reduced this complication compared to earlier RFA approaches. When hoarseness does occur, most patients recover within 2 months. Compare this to surgical parathyroidectomy risks to help patients make informed treatment decisions.

Broader Evidence Context

This study advances the technical optimization of RFA for parathyroid disease. While RFA is well-established for thyroid nodules, its application to parathyroid tissue is more recent. The techniques developed for thyroid RFA—including hydrodissection and moving-shot technique—are being adapted and refined for parathyroid applications.

Current guidelines still consider parathyroidectomy the standard treatment for refractory SHPT, but RFA is gaining recognition as an alternative, particularly for patients at high surgical risk. Studies like this one help establish best practices that may facilitate broader adoption.

Study Limitations

Single-center prospective study with moderate sample size. The historical comparison group (conventional technique) was treated earlier, introducing potential temporal bias from learning curve effects. Long-term PTH control and recurrence rates not detailed in the summary. Operator experience with each technique was not controlled. Specific definitions of “clinical success” would affect interpretation.

Bottom Line

An improved RFA protocol incorporating hydrodissection, short electrodes, low power, and intra-nodular technique significantly increases clinical success and reduces recurrent laryngeal nerve injury in secondary hyperparathyroidism, establishing best practices for this minimally invasive treatment approach.

Source: Yuhan Qiu, et al. “A novel strategy for optimizing safety and efficacy in ultrasound-guided radiofrequency ablation for secondary hyperparathyroidism: a prospective study.” Read article