Ulnar nerve entrapment in Guyon's canal caused by a ganglion cyst: two case reports and review of the literature.

In this article, two cases of ulnar nerve neuropathy in Guyon's canal caused by a ganglion cyst are reported. A review of the literature found 73 cases reported in 35 articles of ulnar neuropathy at the wrist secondary to a ganglion cyst. We investigated the pathogenesis of ganglion cysts, which are separated as extraneural and intraneural. At this anatomical area, there are a variety of clinical factors that can also lead to ulnar nerve compression such us trauma, fracture of the hamate's hook, arterial thrombosis, tumors and other anatomical variations. The symptoms may include weakness, paresthesia, numbness and atrophy of hypothenar muscles. Except the careful clinical assessment, magnetic resonance imaging, ultrasound and electrophysiological control are useful tools regarding our differential diagnosis. The treatment of this clinical condition is surgical. We consider that instant surgical decompression is of the essence and enables postoperatively total recovery. LEVEL OF EVIDENCE: Level III.