Ultrasound-Guided Revision Carpal Tunnel Release for Incomplete Open Carpal Tunnel Release: Using Magnetic Resonance Imaging to Guide Sonographic Access.

Incomplete open carpal tunnel release is a common cause of persistent or worsened median nerve symptoms following surgery. We report a 60-year-old right-hand-dominant man forklift driver who presented with right carpal tunnel syndrome symptoms five months after open carpal tunnel release. After surgery there had been an immediate increase in symptoms. Postoperative nerve conduction studies were essentially unchanged. Office-based ultrasound (US) was not helpful because of scar tissue obscuring the median nerve and transverse carpal ligament in the distal half of the canal. Magnetic resonance imaging (MRI), although reported as normal, demonstrated persistent median nerve compression in the distal canal. MRI delineated the relationship of the median nerve to the residual transverse carpal ligament and the hook of the hamate, confirming that the standard US-guided carpal tunnel release distal release site-adjacent to the hook of the hamate-was free of underlying nerve. The usual entry site for US-guided carpal tunnel release at the lunate was visible on both MRI and US. An US-guided carpal tunnel release was then performed safely from this entry point proximally, with immediate partial resolution of numbness and complete resolution at 3 months. This case illustrates that MRI may show landmarks for safe US-guided surgery when the usual US landmarks cannot be seen. In this case, MRI directed decision making toward US-guided surgery as opposed to open.