Table 1.

Summary of the previous studies on findings of magnetic resonance neurography or ultrasound of hourglass-like constriction neuropathy or neuralgic amyotrophy.

First Author, Year	Evaluation Tool	Summary
Van Rosmalen, 2019 [15]	US	51 patients with NA (upper limb) vs. 50 control subjects Increased cross-sectional areas in the affected nerves.
Kim, 2019 [1]	MRN	2 patients with SSN and 1 patient with SSN + RN Single focal constriction, multiple focal constrictions, diffuse swelling, and increased signal intensity
Sneag, 2018 [9]	MRN	27 patients with NA in the brachial plexus Focal intrinsic constrictions (32 of 38 nerves) Bull’s eye sign
Sneag, 2017 [6]	MRN	6 patients with NA SSN, AN, RN, AIN
Arányi, 2017 [5]	US	53 patients with NA with 70 affected nerves AIN (23%), RN (17%), LTN (17%), SSN (11%), accessory nerve (9%), and AN (7%) Sensitivity of US: 74% Swelling without constriction, incomplete constriction, complete constriction
Noda, 2017 [14]	US	6 patients with segmental swelling (larger cross-sectional diameter) Involved nerves: LTN, SN, MN, MCN, and PIN
Lieba-samal, 2016 [13]	US	4 patients with distal NA in AIN Swelling or hypertrophy of the involved nerves.
Arányi, 2015 [4]	US	14 patients with NA RN, PIN, AIN, SSN, MCN, LTN, MCN, and AN Four types of abnormalities: (1) focal or diffuse nerve/fascicle enlargement; (2) incomplete nerve constriction; (3) complete nerve constriction with torsion (hourglass-like appearance); and (4) fascicular entwinement. The types of abnormalities had no correlation with the prognosis.

Abbreviations: US, ultrasound; MRN, magnetic resonance neurography; NA, neuralgic amyotrophy; SSN, suprascapular nerve; AN, axillary nerve; RN, radial nerve; AIN, anterior interosseous nerve; LTN, long thoracic nerve; MN, median nerve; MCN, musculocutaneous nerve; PIN, posterior interosseous nerve.