Age / Sex : 32 / M

Chief complaint : Sudden onset of upper extremity pain with hand motor weakness


What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer)

Courtesy : 김여주 (Yeo Ju Kim), 한양대학교 병원 (Hanyang University Medical Center)

(incomplete) Hourglass constriction (HC) of deep radial neve

Discussion

Disease definition
Hourglass constriction” of peripheral nerve
a new radiological entity
characterized by a very focal constriction of a nerve, or part of it (one or more fascicles)
The most common involved nerves are the radial nerve (RN) along with the deep radial nerve.

Finding
USG :
1. Hourglass-like incomplete constriction (this case)
- Focal decrease of nerve diameter
- Internal continuity of the nerve retained
- Nerve enlargement on both sides of the constriction, more proximally
- Best seen on longitudinal scans
2. Hourglass-like complete constriction (torsion)
- Hyperechogenic division of the nerve
- Internal continuity of the nerve interrupted
- Marked nerve enlargement on both sides of the constriction, more proximally
- Best seen on longitudinal scans
MRI:
peripheral hyperintensity and central hypointensity of the nerve proximal to the constriction site, on fluid sensitive sequence (bull’s eye pattern)
Central hypointensity: the abnormal fiber(s) of the nerve
peripheral hyperintensity: thickened, edematous surrounding epineurium

References
Arányi Z, Csillik A, Dévay K, Rosero M, Barsi P, Böhm J, Schelle T. Ultrasonographic identification of nerve pathology in neuralgic amyotrophy: Enlargement, constriction, fascicular entwinement, and torsion. Muscle Nerve. 2015 Oct;52(4):503-11. doi: 10.1002/mus.24615
Granata G, Tomasello F, Sciarrone MA, Stifano V, Lauretti L, Luigetti M.Neuralgic Amyotrophy and Hourglass Nerve Constriction/Nerve Torsion: Two Sides of the Same Coin? A Clinical Review. Brain Sci. 2024 Jan 10;14(1):67