Electrodiagnosis and Ultrasound Imaging for Ulnar Nerve Entrapment at the Elbow: A Review

Entrapment neuropathy of the ulnar nerve at the elbow, the so-called cubital tunnel syndrome, is the second most frequent focal mononeuropathy after carpal tunnel syndrome in adults. Currently, there is a pressing need to identify cost-effective biomarkers and procedures capable of accurately detecting alterations in ulnar nerve structural and functional integrity. Established electrophysiological techniques, such as motor and sensory nerve conduction studies, along with needle electromyography of specific muscles, represent the gold standard for ulnar nerve electrodiagnosis. Concurrently, the introduction of neuromuscular ultrasound and its integration into electromyographic laboratories has significantly impacted structural diagnosis and the precise localization of ulnar nerve pathology over the past two decades. In this review, our objective is to summarize the current knowledge on both classical and advanced diagnostic methods utilized in clinical neurophysiology laboratories. We aim to provide a synthesis of modern electrodiagnostic and neurosonographic techniques, with a particular emphasis on easily attainable, clinically relevant parameters.