Abstract
Background: Lacertus syndrome, a condition characterized by median nerve compression at the elbow due to anatomical variations, is often misdiagnosed. This case report describes a 53-year-old female patient who presented with severe lateral elbow and shoulder pain, previously diagnosed with cervicalgia and tennis elbow. Methods: Upon admission, she reported significant pain (NRS-Numerical Rating Scale 8/10) and occasional radiating paresthesia in the first three digits of her left hand. Clinical examination revealed weakness in the wrist and finger flexion, which was exacerbated by a positive Cutaneous Scratch Test (CST), while Magnetic Resonance Imaging (MRI) of the cervical spine showed no definitive abnormalities. Electroneurography (ENG) indicated reduced amplitude in the left anterior interosseous nerve. Ultrasound excluded carpal tunnel syndrome but identified nerve flattening beneath the pronator teres muscle. A surgical decompression of the median nerve was performed, resulting in immediate improvement in muscle strength and significant pain reduction (NRS 1/10) postoperatively. Follow-up evaluations confirmed substantial recovery in nerve function and morphology. Conclusions: This case illustrates the atypical presentation of Lacertus syndrome, emphasizing the need for comprehensive diagnostic approaches that include clinical, imaging, and neurophysiological assessments. Awareness of this syndrome is crucial for differential diagnosis in patients exhibiting uncharacteristic symptoms, such as shoulder or elbow pain, to ensure timely and effective treatment.