Lumbar plexopathy as a complication of percutaneous nephrolithotomy in a horseshoe kidney.

Treatment of nephrolithiasis in horseshoe kidneys can be challenging due to anomalies in renal position, collecting system anatomy and vascular supply. We report on a patient who was referred after a failed percutaneous nephrolithotomy for a left moiety staghorn calculus in a horseshoe kidney. Two punctures had been performed involving upper and middle posterior calyces. Both were very medially placed and inadvertently traversed the psoas muscle, resulting in lumbar plexopathy with permanent deficit. This complication presented postoperatively with left leg weakness, paresthesia, and pain which impaired independent ambulation. The patient went on to be successfully treated for her stone disease with robotic-assisted laparoscopic pyelolithotomy.