Spontaneous Postoperative Reduction of Ulnar Aneurysm by Simple Decompression of Guyon's Canal in a Patient with Hypothenar Hammer Syndrome: A Case Report.

Guyon's canal syndrome is a pathological condition caused by compression of the ulnar nerve at the level of the wrist. It is less frequent than other compression syndromes of the upper limb (cubital and carpal tunnel), and different causative agents, including vascular lesions, are described. Among these, aneurysm of the ulnar artery is described in the literature as an infrequent aetiology. We report the case of a 25-year-old young man with Guyon's canal syndrome caused by an aneurysm of the ulnar artery, who underwent surgical decompression of the Guyon's canal without intervening on the aneurysm. The postoperative course was free of complications, and the patient reported satisfaction, with reduced symptoms. Clinical examination and ultrasound imaging showed mass reduction of the aneurysm in the postoperative period, which appears to be an evolution hitherto undocumented in the literature. Many treatments are available for Guyon's canal syndrome. Past medical and surgical treatments, duration and severity of symptoms, causes, and pathogenesis are important for therapeutic choice. Surgical treatment based on ligament section and lysis of the Guyon's canal downstream, without any action on the aneurysm and with ulnar artery preservation, determined a reduction in terms of volume, relief of the symptoms, and patient satisfaction. With this case we describe a surgical therapeutic option for the treatment of Guyon's canal syndrome caused by an aneurysm of the ulnar artery, in which surgery is limited to canal decompression and consequential aneurysm mass reduction with concomitant relief of symptoms.