Super-voltage PRF of Stellate Ganglion Versus Super-voltage PRF of T2 T3 Sympathetic Ganglia in Managing PMPS. (PMPS PRF)

Rationale for our study:

Supervoltage Pulsed Radiofrequency (SV-PRF) is an advanced neuromodulation technique that delivers higher-voltage short pulses (typically 60-90 V) while keeping tissue temperature below neurodestructive levels (<42°C), allowing deeper electric-field penetration, enhanced C-fiber modulation, and sustained changes in sympathetic outflow without causing structural nerve injury, theoretically providing longer-lasting analgesia and improved safety compared to standard PRF. Among interventional options for sympathetically mediated PMPS, stellate ganglion (SGB) and T2-T3 sympathetic interventions have emerged as promising therapies, yet they differ in mechanism, outcomes, and clinical implications. The current literature lacks direct head-to-head comparisons of these two techniques regarding efficacy, long-term relief, and safety, as most studies evaluate each intervention individually. This knowledge gap, combined with the limited efficacy of conventional pharmacologic treatments, highlights the need for a comparative study to determine which approach offers superior pain relief, durability, safety, and cost-effectiveness. By examining short- and long-term outcomes, as well as resource utilization, this study aims to provide evidence-based guidance to optimize clinical decision-making, help clinicians select the most appropriate intervention for PMPS patients, and establish practical, sustainable treatment strategies. .(33, 34)

Aim of the study:

The aim of this study is to compare the effectiveness of supervoltage pulsed radifrequency of stellate ganglion and supervoltage pulsed radifrequency of T2-T3 sympathetic ganglia in the treatment of postmastectomy pain syndrome.

Primary Objectives:

To assess the degree of pain relief using Visual analogue scale (VAS scores) in 3 groups (Group S: receiving stellate ganglion supervoltage pulsed radiofrequency, Group T: receiving T2T3chains supervoltage pulsed radiofrequency as compared to Group C: Control group on tramadol 150 mg / day and gabapentin 600 mg / day) at different time intervals (baseline, 1 week, 1 month, 3 months, 6 months).

Secondary objectives:

• To compare the dose reduction in Antineuropathic therapy.
• To compare improvements in quality of life and sleep using (Brief pain inventory assessment tool).
• To assess any adverse events or complications related to either procedures
• Patient satisfaction using patient global impression of change (PGIC) Scale.

Methodology:

I. Study design:

Randomized controlled trial involves 3 Groups:

Group S receiving stellate ganglion supervoltage pulsed radiofrequency and Group T receiving T2T3chains supervoltage pulsed radiofrequency.

Group C : Control group on tramadol 150 mg / day and gabapentin 600 mg / day

II. Study setting and location:

Anesthesia and pain management Department, National Cancer Institute, Cairo University after approval by the institutional review board.

III. Study Duration: [18 months]

IV. Inclusion Criteria:

• Female patients aged 18-60 years.
• Patient of class II according to the American society of Anesthesiologists (ASA) physical status classification system .
• History of unilateral mastectomy for breast cancer.
• Persistent pain >3 months postoperatively.
• VAS score ≥4 despite pharmacological management.
• Patients with neuropathic pain who has a score ≥4 by Douleur Neuropathic 4 question (DN4) questionnaire. (42)
• Patients on more than 1 antineuropathic drug.

V. Exclusion Criteria:

• Coagulopathy or anticoagulant therapy.
• Local infection at injection site.
• History of psychiatric illness or cognitive dysfunction.
• Previous intervention in the same region (e.g., prior stellate ganglion block or thoracic radiofrequency ablation).
• Allergy to local anesthetics or contrast agents.

VI. Randomization and blinding:

This prospective, randomized, controlled trial will allocate eligible Patients into three groups in a 1:1:1 ratio using a computer-generated randomization sequence:

• Group S : Stellate Ganglion supervoltage pulsed radiofrequency.
• Group T : T2-T3 chains supervoltage pulsed radiofrequency.
• Group C Control group on tramadol 150 mg / day and gabapentin 600 mg / day. Allocation concealment will be maintained with sequentially numbered, opaque, sealed envelopes prepared by an independent investigator not involved in recruitment, intervention or outcome assessment Given the nature of the interventions, patient blinding is not feasible; however, outcome assessors will remain blinded to group allocation. The interventionalist performing the procedures will not participate in follow up assessment or data collection. All statistical analysis will be conducted by statistician blinded to group assignment to minimize the bias and ensure methodological rigor.

VII. Procedure Details:

Group S - Stellate Ganglion technique:

· Super-voltage pulsed radiofrequency (PRF) of the stellate ganglion was performed under strict aseptic precautions with standard monitoring. Patients were positioned supine with a slight extension of the neck and head turned contralaterally. Ultrasound guidance using a high-frequency linear transducer was employed to identify the stellate ganglion region at the level of the C6 transverse process, anterior to the longus colli muscle and medial to the carotid sheath. A 22-gauge radiofrequency cannula (5-10 cm length, 5-mm active tip) was advanced using an in-plane technique until the needle tip was positioned adjacent to the sympathetic chain on the surface of the longus colli muscle. After negative aspiration, sensory (50 Hz) and motor (2 Hz) stimulation were performed to confirm appropriate needle placement and exclude somatic nerve involvement. Pulsed radiofrequency was then delivered using a supervoltage protocol with a pulse width of 20 ms at a frequency of 2 Hz, applying high voltage output (up to 60-65 V) while maintaining the target tissue temperature below 42°C for a total duration of 120-240 seconds. The procedure was intended to achieve neuromodulation of sympathetic fibers without thermal neurodestruction. Procedural success was assessed by the development of ipsilateral Horner's syndrome, increased upper limb temperature and subsequent decrease in pain. (35,39)

Group T- T2-T3 SUPERVOLTAGE PRF:

Position the patient prone with bolsters to minimize lordosis and allow C- arm AP and oblique imaging. Under sterile conditions use fluoroscopy to identify T2 and T3 pedicles, ribs and transverse processes. A posterior paravertebral (transforaminal-style) approach is commonly used: advance a curved RFA cannula (20-22G, 10-15 cm with 5-10 mm active tip) under fluoroscopic AP and lateral guidance to the anterolateral aspect of the vertebral body or just anterior to the costotransverse junction at the T2 and T3 levels, the expected location of the thoracic sympathetic chain. Confirm needle position with small (0.5-1 mL) contrast injection to exclude intravascular or pleural spread. Perform sensory (50 Hz) and, if applicable, motor (2 Hz) stimulation to exclude intercostal motor/pleural/nerve root proximity. For supervoltage PRF, deliver radiofrequency with pulse width 20ms at 2 Hz while maintain the electrode tip temperatue less than 42°C for 120-240 seconds at each level. Monitor for immediate complications (pneumothorax, vascular uptake, new motor deficit) and observe clinical endpoints such as ipsilateral temperature rise and pain reduction. Provide post-procedure chest imaging if pneumothorax suspected. Patient selection, careful contrast checks and stimulation testing minimize complications and improve targeting accuracy .(36,37,38)

VIII. Outcome Measures:

Primary Outcome:

Change in VAS score in groups at different time intervals (baseline, 1 week, 1 month, 3 months, 6 months).(40)

· Secondary Outcomes:

1. Change in Brief Pain Inventory (BPI) (41) score reflecting functional improvement.
2. dose reduction in antineuropathic drugs
3. Patient satisfaction using patient global impression of change (PGIC)scale.42
4. procedural complications.

IX. Follow-up Intervals:

1 week, 1 month, 3 months, 6 months post-procedure.