RADIOFREQUENCY OR PHENOL FOR GANGLION IMPAR NEUROLYSIS IN PERINEAL CANCER PAIN: RESPONDER RATES AND DURATION OF RELIEF IN A RANDOMIZED TRIAL

Abstract

Ganglion impar neurolysis with phenol is widely used for perineal cancer pain, but its effect may be short-lived, whereas radiofrequency thermocoagulation produces a controlled thermal lesion that may give more durable relief. We compared the analgesic efficacy and the duration of pain relief of conventional radiofrequency thermocoagulation and phenol neurolysis of the ganglion impar in a randomized, double-blind trial. Patients with perineal cancer pain (visual analogue scale score of 5 or more) refractory to tramadol and pregabalin and responsive to a diagnostic block received fluoroscopy-guided radiofrequency thermocoagulation (80 °C for 120 s) or neurolysis with 4–6 mL of 8% phenol. The primary outcome was the proportion of patients achieving at least a 50% reduction in pain score. Secondary outcomes were pain scores, duration of pain relief, and tramadol and pregabalin consumption over 3 months. Forty patients (20 per group) completed the study. Responder rates were similar up to 2 weeks (100% vs 90–100%) but were significantly higher after radiofrequency thermocoagulation at 1 month (80% vs 45%; P = 0.022), 2 months (55% vs 20%; P = 0.022) and 3 months (30% vs 0%; P = 0.020). The median duration of pain relief was 3 months after radiofrequency thermocoagulation and 1 month after phenol neurolysis (log-rank P = 0.002). Pain scores were lower after radiofrequency thermocoagulation at every time point (3.90 ± 0.45 vs 4.90 ± 0.45 at 3 months; P < 0.001), and tramadol and pregabalin consumption was lower at every follow-up visit (P ≤ 0.010). Conventional radiofrequency thermocoagulation of the ganglion impar provided a significantly longer duration of pain relief than phenol neurolysis, with consistently lower pain scores and analgesic requirements. Larger trials are needed to confirm the size of this advantage.