Thoracoscopic delivery of therapeutics in the swine sympathetic chain: Implications for future neuromodulation

The thoracic sympathetic chain is implicated in several disease processes including palmar hyperhidrosis and complex regional pain syndrome. These diseases are often medically refractory and require surgical treatments including sympathectomies and ganglion blocks. The use of chemogenetic or optogenetic technologies to modulate sympathetic chain activity may be a potential treatment for these diseases. However, there is no established thoracoscopic surgical approach to deliver viral vectors into the thoracic sympathetic chain and ganglia. Our objective was to evaluate the feasibility of thoracoscopic injection of the swine sympathetic chain. Two Landrace farm pigs underwent a novel procedure for thoracoscopic sympathetic chain injections. One was non-survival and one was a five-day survival surgery. Both procedures successfully delivered methylene blue in the thoracic sympathetic chain. Over the five-day postoperative period, the animal displayed stable vital signs. Thoracoscopic targeted injections of the sympathetic chain is a feasible approach to deliver therapeutics in swine. Future studies should investigate the use of transgene expression as a potential means to control sympathetic output for the development of novel therapies for palmar or axillary hyperhidrosis, thoracic neuropathic pain syndromes and select peripheral vascular diseases.