KTP Laser Nerve Sparing Radical Prostatectomy: Comparison of Ultrasonic and Cold Scissor Dissection on Cavernous Nerve Function

Purpose: Energy sources used during nerve sparing radical prostatectomy are known to compromise cavernous nerve function. Lasers offer the potential for accurate dissection while minimizing collateral injury to delicate neural structures. We evaluated cavernous nerve function following KTP laser dissection and compared outcomes to those of ultrasonic shears and cold scissor dissection. Materials and Methods: Laparoscopic unilateral neurovascular bundle mobilization was performed in 36 survival dogs using a KTP laser, ultrasonic shears and an athermal technique with cold scissors and clips in 12 each. Peak intracavernous pressure upon cavernous nerve stimulation, expressed as a percent of mean arterial pressure, was measured acutely and at 1 month. Thermal spread from the KTP laser and ultrasonic shears was assessed histologically ex vivo in harvested peritoneum. Results: Median peak intracavernous pressure as a percent of mean arterial pressure was similar immediately and 1 month after laser and athermal dissection, and significantly decreased after dissection with ultrasonic shears. Acute peak intracavernous pressure as a percent of mean arterial pressure was 53%, 96% and 98% for ultrasonic shears, laser and the athermal technique, respectively (laser vs athermal p = 0.51, ultrasonic shears vs laser p < 0.001 and ultrasonic shears vs athermal p < 0.001). Chronic peak intracavernous pressure as a percent of mean arterial pressure was 56%, 98% and 100% for ultrasonic shears, laser and the athermal technique, respectively (laser vs athermal p = 0.38, ultrasonic shears vs laser p = 0.016 and ultrasonic shears vs athermal p = 0.013). The median depth of acute laser injury was 600 mu m compared to 1.2 mm for ultrasonic shear dissection and 450 mu m crush injury due to the athermal technique. Thermography revealed less collateral thermal spread from the laser than from the ultrasonic shears (median greater than 60C thermal spread 1.07 vs 6.42 mm, p < 0.01). Conclusions: The KTP laser was comparable to the athermal technique and superior to the ultrasonic shears for preserving cavernous nerve function.