A Rare Case of Guyon's Canal Syndrome Caused by Cystic Adventitia Degeneration: High-Resolution Ultrasound Findings

Introduction

Entrapment of the ulnar nerve inside the ulnar tunnel, which is also called Guyon’s canal, is a well-known entity leading to pain, numbness and loss of function in the part of the hand supplied by the ulnar nerve. Space-occupying lesions in this area, such as ganglions, tendinitis, fracture, arthritis, nonspecific edema and thromboangitis, may cause the entrapment of the nerve, known as ulnar tunnel syndrome.

Cystic adventitial disease (CAD) is a rare benign vascular lesion, where cysts form in the adventitia of a blood vessel, first described in the iliac artery (Atkins HJ, Key JA. Br J Surg 1947; 34: 426). CAD may cause local pain due to the stenosis and occlusion of the vessel and can be treated either with US- or CT-guided percutaneous cyst aspiration or surgery (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155: 309 – 321).

For unknown reasons, most of the CAD cases reported thus far involve the popliteal artery in young middle-aged men (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155:309 – 321). A few cases have also been described in the external iliac, common femoral, axillary, distal brachial, and radial arteries.

Although the pathomechanisms of CAD remain controversial, a theory of joint-related origin has been suggested, similar to the pathogenesis of intraneural ganglion cysts (Spinner RJ et al. Clin Anat 2013; 26: 267 – 281). The diagnosis can be established with high-resolution ultrasound and MRA as the first-choice imaging methods (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155: 309 – 321).

We report here a unique case of cystic adventitial degeneration that affected the ulnar artery and caused ulnar nerve palsy, which was detected with high-resolution ultrasound.