Application of Ultrasound in an Ulnar Motor Nerve Conduction Study after Anterior Ulnar Nerve Transposition

Ulnar nerve entrapment at the elbow (cubital tunnel syndrome) is one of the most common peripheral nerve entrapments. Surgical management of cubital tunnel syndrome often involves anterior transposition of the ulnar nerve. After surgical treatment of ulnar neuropathy, patients will often be referred for a repeat nerve conduction study (NCS) to assess for changes in conduction velocity. However, in a patient with a transposed ulnar nerve, it is technically difficult to localize the proper NCS stimulation sites, requiring nerve mapping by multiple submaximal stimulations. We present a case report utilizing ultrasound to localize and map the transposed ulnar nerve for the ulnar motor NCS test across the elbow. As a result, the need for nerve mapping through repeated stimulation is eliminated.