Variant Distal Ulnar Nerve Loop: A Previously Undescribed Anatomical Finding

Marinacci Anastomosis: A Case Report

Marinacci anastomosis or the reverse Martin-Gruber anastomosis is a rare anomalous intercommunication from the ulnar nerve to the median nerve in the forearm. A young lady was involved in a road traffic accident that resulted in the fracture of both forearm bones for which she was treated surgically. A nerve conduction study was performed later on, which incidentally demonstrated findings of this communication. Knowledge of this anastomosis can help prevent misdiagnosis of clinical findings and misinterpretation of electrophysiological studies and help mitigate iatrogenic injury during surgical procedures.

Report of a Transligamentous Ulnar Nerve Sensory Branch

Background: Several anatomical variations of the median nerve recurrent motor branch have been described. No previous reports have described the anatomical variation of the ulnar nerve with respect to transverse carpal ligament. In this article, we present a patient with symptomatic compression of the ulnar nerve found to occur outside the Guyon canal due to a transligamentous course through the distal transverse carpal ligament. Methods: A 59-year-old, right-hand-dominant male patient presented with right hand pain, subjective weakness, and numbness in both the ulnar and the median nerve distributions. Electromyography revealed moderate demyelinating sensorimotor median neuropathy at the wrist and distal ulnar sensory neuropathy. At the time of planned carpal tunnel and Guyon canal release, a transligamentous ulnar nerve sensory common branch to the fourth webspace was encountered and safely released. Results: There were no surgical complications. The patient's symptoms of numbness in the median and ulnar nerve distribution clinically improved at his first postoperative visit. Conclusions: We have identified a case of transligamentous ulnar nerve sensory branch encountered during carpal tunnel release. To our knowledge, this has not been previously reported. While the incidence of this variant is unknown, hand surgeons should be aware of this anatomical variant as its location puts it at risk of iatrogenic injury during open and endoscopic carpal tunnel release.