The role of electromyography and nerve conduction studies in ulnar longitudinal deficiency: a case report

Background. Ulnar longitudinal deficiency (ULD) is a rare disorder that generally affects the entire upper limb, including the elbow, forearm, and hands. This case study investigates how nerve conduction studies (NCS) and electromyography (EMG) contribute to ULD. Although structural abnormalities of the ULD are well known, there is still a scarcity of information regarding nerve function. Our discoveries of cross-innervation and axonal neuropathy offer novel perspectives on nerve variations in congenital upper limb abnormalities. Case report. A 17-month-old girl with ULD affecting her right upper extremity, which was supported by radiological examination. The NCS indicated axonal sensory neuropathy of the right median and ulnar nerves and cross-innervation from median to ulnar nerve. The median, ulnar, radial motor, and radial sensory nerves were all normal. Needle EMG revealed normal motor unit action potentials in all muscle samples. EMG and NCS serve as diagnostic screening tools, providing valuable information to identify and locate nerve pathology. Conclusions. Thorough knowledge and prompt management of motor and neurological abnormalities are crucial for ULD patients’ future functionality. These findings may benefit rehabilitation management and surgical planning.