ENDOSCOPIC THORACIC SYMPATHECTOMY - EVALUATION OF PULSATILE LASER, NON-PULSATILE LASER, AND RADIOFREQUENCY-GENERATED THERMOCOAGULATION

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd: YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83+/-1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd: YAG laser required 153+/-13 Joules and 554+/-47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810+/-50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd: YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd: YAG (3 mm). Our data shows that excimer and CO2 laser produce discrete lesions with minimal damage to surrounding structures. It also demonstrates the safety and reliability of endoscopic denervation, particularly for bilateral denervation which can be performed in one sitting without the added morbidity of a thoracotomy incision.