200 Section - Hourglass-Like Constrictions in Neuralgic Amyotrophy: The Diagnostic Value of Magnetic Resonance Neurography and High-Resolution Ultrasonography

Wednesday, May 20, 2026

6:00 PM - 7:30 PM PT

Presenting Author/Autor expositor(s)

DK

Du Hwan Kim, MD, PhD

Professor
Chung-Ang University Hospital
Seoul, Seoul-t'ukpyolsi, Republic of Korea

Co-Author/Coautor(s)

YL

Yong-Taek Lee, MD

Professor
Kangbuk Samsung Hospital
Seoul, Seoul-t'ukpyolsi, Republic of Korea

Case Diagnosis: Neuralgic amyotrophy (NA) is characterized by sudden onset of severe upper limb pain followed by muscle weakness and atrophy. Although NA was traditionally regarded as a brachial plexus disorder, it is now understood to affect various peripheral nerves, resulting in diverse clinical manifestations and prognoses. Recent advances in magnetic resonance neurography (MRN) and high-resolution ultrasonography have improved visualization of nerve pathology, particularly hourglass-like constrictions, which are observed in most NA patients during the acute phase.

Case Description:

The report contains two cases of NA evaluated using MRN and ultrasonography. The first case involved a 29-year-old woman who presented with weakness in flexion of the first, second, and third fingers of the left hand. MRN and high-resolution ultrasonography revealed two hourglass-like constrictions in the median nerve at the mid-humerus level, and intraoperative findings confirmed lesions at the same site. The second case involved a 47-year-old man presenting with left wrist drop. A constriction of the radial nerve between the radial groove and the lateral epicondyle was revealed by MRN and high-resolution ultrasonography, for which neurorrhaphy was subsequently undergone.

Discussions: Our cases suggest that the 'hourglass-like constriction' sign may serve as an important radiological indicator for diagnosing NA. Ultrasonography may reveal findings such as segmental swelling, constriction and torsion of the affected nerves in patients with NA. MRN can visualize the extent of involved nerves, severity and the numbers of constriction.

Conclusions: The role of imaging diagnostic tools such as MRN and high-resolution ultrasonography has become increasingly important in this context of conceptual expansion. These tools are not only important for diagnosis but also for guiding plan of treatment. However, further research is still needed to determine the optimal timing and techniques for surgery, and additional studies are also required to explore the necessity and application of MRN and ultrasonography.