The Distal Spine: Normal Embryogenesis and Derangements Leading to Malformation.

The spine and spinal cord are composed of multiple segments initiated by different embryologic mechanisms and advanced under different systems of control. In humans, the upper central nervous system is formed by primary neurulation, the lower by secondary neurulation, and the intervening segment by junctional neurulation. This article focuses on the distal spine and spinal cord to address their embryogenesis and the molecular derangements that lead to some distal spinal malformations.

Percutaneous transhepatic holmium laser lithotripsy of a large common bile duct stone.

A 58-year-old woman presented with a 4 cm obstructing choledocolith within the proximal common bile duct. She had an extensive operative history resulting in common bile duct to jejunum anastomosis after cholecystectomy. Endoscopic retrograde cholangiopancreatography (ERCP) removal was unsuccessful, and surgical exploration was contraindicated due to multiple comorbidities. Interventional radiologist placement of bilateral transhepatic ureteral access sheaths allowed Urologist evaluation of the biliary tract by ureteroscope. Holmium laser lithotripsy was performed with successful fragmentation of the stone and clearance of the obstruction, without complication. The case is relevant to the growing literature on the management of refractory biliary stones after failed ERCP.