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E1614. Median Nerve Ultrasound: Beyond Carpal Tunnel Syndrome
Authors
  1. Nikesh Patel; Mayo Clinic
  2. Christin Tiegs-Heiden; Mayo Clinic
  3. Gavin McKenzie; Mayo Clinic
  4. Michael Moynagh; Mayo Clinic
  5. Katrina Glazebrook; Mayo Clinic
Background
Ultrasound is an increasingly utilized method for first line evaluation of peripheral nerves imaging in the upper extremity. Benefits over magnetic resonance imaging (MRI) include better spatial resolution, portability, easy patient access, ability for dynamic evaluation, and lower cost. In addition, ultrasound can be performed on patients who cannot tolerate or may have contraindications to MRI. In conjunction with clinical history and electromyography, ultrasound is an important clinical tool for evaluation of peripheral nerves in the upper extremity. One of the most common indications for upper extremity ultrasound is to evaluate the median nerve in the setting of carpal tunnel syndrome, which affects approximately 3-6% of adults in the general population. Given that the median nerve is frequently interrogated at ultrasound, it is important for both sonographic technologists and interpreting radiologists to be familiar with the relevant anatomy as well as some of the common and less commonly encountered findings on sonographic evaluation of the median nerve. The purpose of this exhibit is to review sonographic evaluation of the median nerve and highlight examples of common and uncommon findings. Via a case-based approach, this exhibit will review a variety of clinical presentations, sonographic findings with multimodality correlation, treatment options and/or outcomes.

Educational Goals / Teaching Points
After viewing this presentation, the reader should have an increased understanding of sonographic evaluation of median nerve and relevant anatomy in the context of both common and uncommonly encountered findings and diagnoses. The exhibit will highlight clinical features of carpal tunnel syndrome and demonstrate a variety of potential causes for median nerve neuropathy via both intrinsic and extrinsic mechanisms. Specific intrinsic examples of pathology include a case of intraneural lipoma and a case of median nerve benign peripheral nerve sheath tumor. Specific extrinsic examples of pathology include a case of thrombosed anomalous vessel and a case of a complex cystic structure, both contributing to symptoms of median nerve neuropathy. The presentation will broaden differential diagnostic considerations and assist radiologists in providing accurate interpretation.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Median nerve dysfunction may occur from both intrinsic and extrinsic sources. This exhibit will highlight the important landmarks used for evaluation of the median nerve as well as abnormal findings on sonographic evaluation. Pathology occurring both at and proximal to the carpal tunnel will be discussed. Imaging examples of normal and abnormal median nerve ultrasounds will be reviewed in conjunction with multimodality imaging and pathologic diagnosis.

Conclusion
Sonographic evaluation of the median nerve plays an important role for patients with symptoms of carpal tunnel syndrome. An understanding of the relevant anatomy as well as the potential causes and pathology, both within and outside of the carpal tunnel, will assist radiologists to accurately interpret exams and triage patients for appropriate care.