DOI: https://doi.org/10.36347/sjmcr.2026.v14i05.020

Pages: 948-951

Thoracic outlet syndrome (TOS) is a dynamic neurovascular compression disorder, and non-traumatic, posture-related forms may be overlooked on static imaging. We report a 45-year-old female anesthesiologist who developed intermittent numbness and weakness of the left arm exclusively during arm abduction in the sitting or standing position. Computed tomographic angiography showed no fixed structural or vascular abnormality; however, dynamic ultrasonography demonstrated marked narrowing of the costoclavicular space with compression of the brachial plexus and subclavian artery during provocative positioning, reproducing the patient’s symptoms and supporting a diagnosis of functional TOS. Conservative management, including postural correction, scapular stabilization exercises, targeted physical therapy, ultrasound-guided fascial release, and ergonomic modification, resulted in partial symptomatic improvement. Follow-up dynamic ultrasonography showed reduced but persistent positional compression. This case highlights that normal static imaging does not exclude thoracic outlet syndrome and supports the clinical value of dynamic ultrasonography for identifying posture-dependent neurovascular compression.