Objective: To characterize the ultrasonographic findings on nerves in neuralgic amyotrophy.Methods: Fourteen patients with neuralgic amyotrophy were examined using high resolution ultrasound.Results: Four types of abnormalities were found: 1. Focal or diffuse nerve / fascicle enlargement (57%), 2. incomplete nerve constriction (36%), 3. complete nerve constriction with torsion (50%) (hourglass-like appearance), and 4. fascicular entwinement (28%). Torsions were confirmed intraoperatively and occurred on the radial nerve in 85% of the patients. A significant correlation was found between no spontaneous recovery of nerve function and constriction / torsion / fascicular entwinement (p=0.007).
Conclusion:Ultrasonographic nerve pathology in neuralgic amyotrophy varies in order of severity from nerve enlargement to constriction to nerve torsion, with treatment moving from conservative to surgical. We postulate that the constriction caused by inflammation is the precursor of torsion and that the development of nerve torsion is facilitated by rotational movements of limbs.