This document outlines lumbar sympathectomy, a procedure to remove at least one sympathetic ganglion. It discusses the anatomy, indications, contraindications, types of procedures, operative steps, and complications. The key indications for lumbar sympathectomy include hyperhidrosis, causalgia, inoperative arterial occlusive disease causing rest pain or ulceration, and Raynaud's phenomenon. Potential complications include post-sympathectomy neuralgia, retrograde ejaculation, bleeding, and rarely paraplegia or ureteric necrosis. The document provides an overview of this irreversible surgical procedure.