Lacertus syndrome (LS) involves median nerve compression by the lacertus fibrosus at the elbow. Often misdiagnosed as carpal tunnel syndrome (CTS), it presents primarily with hand weakness, fatigue, and forearm pain, with less common sensory symptoms.

To review current knowledge on the clinical features, diagnostic methods, and treatment options for LS, highlighting the distinct characteristics that differentiate it from similar conditions.

A comprehensive review synthesizing literature on anatomy, pathophysiology, prevalence, diagnostic approaches, and treatment outcomes.

Clinical diagnosis relies heavily on specific provocative tests, including the clinical triad (muscle weakness, localized pain, positive Scratch Collapse Test), Lacertus Antagonist Test (LAT), and visible Lacertus Notch Sign. Diagnostic ultrasound is increasingly preferred for real-time, dynamic assessment. Electrodiagnostic studies have limited diagnostic value due to the dynamic nature of the compression. Conservative treatments include activity modification, nerve gliding exercises, kinesiotaping, and injections (corticosteroids, botulinum toxin). Surgical intervention, typically via minimally invasive or percutaneous release under Wide-Awake Local Anaesthesia No Tourniquet (WALANT), achieves immediate intraoperative strength improvement and high patient satisfaction rates (around 88%).

Improved clinical recognition of Lacertus syndrome through specific provocative tests and dynamic ultrasound enhances accurate diagnosis. Surgical decompression, especially using the WALANT approach, consistently yields excellent functional outcomes, emphasizing its role as the definitive treatment for resistant or severe cases.